DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

Professional Paper 105 

, 

HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA 

BY 

GROVE KARL GILBERT 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1917 
ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FF.OM 

THE SUPERINTENDENT OF DOCUMENTS 

GOVERNMENT PRINTING OFFICE 

WASHINGTON, D. C. 

. AT 

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/:::,. 
CONTENTS. 

Preface ......................................... . 

Abstract ........................................ . 

Chapter I. Introduction ........................... . 

Chapter II. Natural condition of the Sacramento 

basin with respect especially to the movement of 

detritus and the regimen of rivers ............... . 

Chapter III. Subsidence of the land ............. . 

Chapter IV. Changes in the condition of rivers 

from artificial causes ........................... . 

Changes due to mining .. _ ..................... . 

Changes due to reclamation .................. . 

Trans_portation of debris ...................... . 

Accumulations of debris in the mountains .... . 

Piedmont deposits .......................... . 

Deposits in the valley rivers ................. . 

Chapter V. Changes in the condition of bays ... ., .. . 

Chapter VI. Quantity and distribution of detritus .. 

Data to be determined ....................... . 

Q'uantity of mining debris .................... . 

Quantity of debris from sources other than 

mialing ................................... . 

Agriculture ............................. . 

Roads .................................. . 

'!'rails ....................... -. -· · · · · · · · · · 

Grazing ................................ . 

Nat ural degradation of the surface ....... . 

Summary .............................. . 

Distribution of the detritus ................... . 

Deposits within the Sierra Nevada ........... . 

DepQsits of the piedmont belt. .............. . 

Deposits in the valley rivers ................. . 

Deposits in the bays and in the ocean ........ . 

Deposits on valley lands and delta marshes ... . 

New waste from old mines .................. . 

Chapter VII. Studies on the lower Yuba .......... . 

Detrital load of Yuba River ................. . 

Relation of the Ytiba's load to other estimates. 

Scouring ,below the barrier .................. . 

Seepage ............. , ...................... . 

Remodeling of channel. .................... . 

Dagu~rre Point dam and training walls ........ . 

Chapter VIII. Looking forward .................. . 

River debris from sources other than mining .. . 

Restraint of debris on the Yuba .............. . 

Flood control in the Sacramento Valley ..... . 

Mining debris now stored i~ the mountain and 

piedmont deposits ........................ . 

Future distribution of debris ................ . 

Chapter IX. Relations of debris movement to the 

Golden Gate bar ................... , ............. . 

Processes and conditions ..................... . 

The effective tidal prism .................... . 

Mean tidal volume at the Golden Gate ....... . 

The open-water effective prism ........... . 

Water storage on marshes ................ . 

Page. 

7 

8 

11 

14 

16 

25 

25 

2b 

26 

Chapter IX. Relations of 'debris movement to the 

Golden Gate bar-Continued. 

Tropic tidal volume at,the Golden Gate ..... . 

Check computations of volume .............. . 

Tidal volumes at other points ............... . 

Reduction of tidal volume in the Golden Gate 

by encroachments on the tidal prism ........ .. 

Velocities ................ .& .................. . 

Comparison of velocities with the character of 

the debris in transit ..................... .. 

Sources of bar material. ...................... . 

Observed changes in the bar ................ . 

27 Interpretation of observed changes .......... . 

28 Summary .................................. . 

29 Pinole Shoal and Mare Island Strait .......... . 

32 Chapter X. The outlook for hydraulic mining .... . 

38 Appendix A. Observations of currents in the Gol38 den Gate ................................. . 

38 Purpose and plan of the work ............... . 

The observations ........................... . 

43 Lag of slack water ........................... . 

43 River-discharge data ....................... . 

44 Tidal volume .................•............. 

44 Appendix B. The tidal prism of tidal marshes .... . 

44 Observations in Ravenswood Slough .......... . 

45 Volume .................................... . 

45 

46 

46 

47 

Relation .of discharge variation to the tidal 

period· ................................ · .... . 

Relation of tidal storage to the rise and fall of 

tide at the mouth of Ravenswood Slough .... 

48 Relation of tidal storage in Ravenswood marsh 

48 to rise and fall of tide at the Presidio .... ~ .. . 

49 Computations of average depth of storage ..... . 

50 Table of storage depth ................. . 

52 Curves of frequency ................... .. 

52 General average ........................ .. 

58 Overmarsh-tide and channel-tide averages. 

58 Tropic tides ............................ . 

60 Summary of computed results ............ . 

60 Lag of slack water .......................... .. 

61 Appendix C. Comparison of surveys .of the bar at 

64 the entrance to San Francisco Harbor .......... . 

64 General statement .......................... . 

64 

65 

67 

'67 

69 

Northern division.~ ........................ . 

Middle division ............................. . 

Southern division .... , ..................... . 

The top of the bar ......... · ................. . 

Migration of the crest line ................... . 

Summary of changes .................. · ...... . 

Accidental errors ............................ . 

69 Systematic errors ........................... . 

71 Index ......................................... . 72 

72 

75 3 

Page. 

79 

82 

83 

85 

88 

90 

91 

94 

95. 

100 

101 

104 

108 

108 

108 

116 

120 

121 

123 

123 

125 

127 

130 

133. 

135 

135 

135 

136 

136 

136 

136 

136 

139 

139 

142 

142 

143 

143 

145 

145 

146 

146 

149 
1. Height of mean tide above zero of United States 

Coast and Geodetic Survey tide gage at the 

Presidio, Cal., separately computed from the 

observations for each year. ... ~ ............ . 

· 2. Low-water records of Yuba River at Marysville 

and of Sacramento River at Sacramento ..... 

3. Data on sedimentR{y deposits in San Pablo 

B:;~.y ...... · ............................... . 

4. Data on sedimentary deposits in San Francisco 

Bay ...................................... . 

5. Estimates of the volumes of debris deposited in 

. the San Francisco Bay system from 1849 to 

1914, inclusive ............................ . 

6. Volume of hydraulic excavation in part of the 

Yuba River basin as estimated by G. K. Gilbert in 1908 and by F. C. Turner in 1889-90 .. 

7. Summary of mining debris, 1849-1909 ......... . 

8. Summary of waste from the land surface of the 

Sacramento and San Joaquin basins from 

1850 to 1914 .............................. . 

9. Estimates of the distribution in the year 1914 of 

debris moved· by mining operations or by 

rains from lands draining to the San Francisco 

Bay system during the preceding 65 years ... 

10. Material arrested by barrier No. 1, Yuba River, 

between October, 1905, and October, 1906 .... 

11. Discharge of Yuba River during period&J of high 

water between October 1, 1905, and October 

1, 1906 ............. · ..................... · .. 

12. Suspended matter in Yuba River at Smartsville 

gaging station for 10-day periods in 1906 ..... 

13. Suspended matter in samples of water collected 

from Yuba River at Marysville January 19, 

1906 ..................................... -·-

14. Materialpassing over barrier No.1, Yuba River, 

between October, 1905, and October, 

1906 ..................................... . 

15. Data for mean effective tidal prism of San Francisco Bay system as affecting the discharge at 

the Golden Gate ............ ~ ............ . 

16. Computation of the ~ean tidal volume at the 

Golden Gate, so far as given by the effective 

tidal prisms of the bays and other bodies of 

open water .................... · ........... . 

17. Average tidal storage on marsh tracts 6f San 

Francisco Bay system, as affecting tidal discharge at the Golden Gate ................ . 

18. Average volume flowing through the Golden 

Gate during a flo~d or ebb tide ............ . 

19. Estimate of the average volume of great tropic 

ebb currents at the Golden Gate ........... . 

20. Relations between general means of tidal range 

in the Golden Gate and mean tidal volumes 

estimated by the prism method ........... . 

21. Comparison of estimates of tidal volume at the 

Golden Gate ............................ . 

4 

TABLES. 

Page. 

22. Estimates of the average volume of great trC?pic 

ebb currents at San Pablo Narrows, Pinole 

Page 

Shoal, and Carquinez Strait............... 83 

19 23. Comparison of the volumes of tide water contributed by certain bodies of water and mars~ to 

Z9 the tropic ebb currents of different straits and 

channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 

33 24. Data illustrating the relation which encroachments on the tidal prism bear to the volume 

33 of tidal currents in the· Golden Gate. . . . . . . . 86 

25. Reduction of tidal c.urren_ts in the Golden Gate 

caused by deposition of mining and other 

37 debris on the shoals of the bays. . . . . . . . . . . . 87 

26. Velocities of ebb currents at the time of greatest 

strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 

40 27. Comparison of velocities of tropic ebb current 

43 with coarseness of debris constituting channel bed................................... 91 

28. Comparison of observed changes of the Golden. 

46 Gate bar with changes theoretically due to 

specific causes. . . . . . . . . . . . . . . . . . . . . . . . . .. . . 99 

29. Irrigation and power from Yuba River project.. 107 

30. Lunar epochs associated with periods of observa50 tion of tidal currents at the Golden Gate. . . . 109 

31. Observations of tidal currents in the Golden 

54 Gate, September, 1914..................... 110 

32. Estimates of the lag of slack water in the Golden 

Gate..................................... 117 

55 33. Comparison of the lag of slack water in the 

Golden Gate with associated data.......... 118 

56 34. Lag of slack water in the Golden Gate and diurnal inequality of tides at Presidio wharf. . . . . 119 

35. Discharge measured at gaging stations and ratio 

56 of precipitation in the same regions......... 121 

57 

73 

75 

78 

79 

81 

82 

83 

36. Velocity, time, and volume of ebb and flood 

37. 

38. 

39. 

40. 

41. 

42. 

43. 

44. 

45. 

46. 

tides in the Golden Gate. . . . . . . . . . . . . . . . . . 122 

Tidal data at station on Ravenswood Slough and 

comparative data at the Presidio wharf. ..... 

Comparison of graphic generalization on depth 

of tidal storage with individual determinations .................................... 

Comparison of ranges of tides at Ravenswood 

Slough and at the Presidio wharf ........... 

Second comparison of graphic generalization of 

tidal storage with individual determinations 

Depth of tidal storage in Ravenswood marsh ... 

Lag of slack water after high water and low 

water at Ravenswood Slough station. : .... ~ . 

Precision of soundings in surveys of the Golden 

Gate bar .................................. 

Comparison of mean depths of water on 4-fathom 

bank, 1873 and 1900 ....................... 

Changes in the middle division of the Golden 

Gate bar, 1873 to 1900 ...................... 

Estimates of mean depth of water on crest-line 

tract~ of the Golden Gate bar in 1873 and 1900. 

126 

133 

133 

135 

136 

137 

140 

142 

143 

144 
ILLUSTRAriONS. 

PLATE I. Hydraulic mining and mining debris .... : .............. -.. ....... . 

II. Topographic types in the western 

part of the Sierra Nevada ..... . 

III. Features illustrating subsidence .. 

IV. Features illustrating subsidence .. 

V. Mining debris near its source ..... 

VI. Change of condition caused by 

mining debris ... · ............. . 

VII. Mining debris of river canyons and 

upland creeks ................. . 

VIII. Mining-debris deposits of upland 

creeks ........................ . 

IX. Culmination of the Yuba River 

piedmont deposit at Parks Bar 

Bridge ........................ . 

X. Hydrau~ic placer mines .......... . 

XI. Exhausted placer diggings ....... . 

XII. Natural protection against soil 

waste ........................ . 

XIII. Soil protection and the attack by 

rain ......................... . 

XIV. Soil waste determined by agriculture .......................... . 

XV. Erosion occasioned by roads ..... . 

XVI. Erosion occasioned by trails ...... . 

XVII~ Erosion occasioned by overgrazing 

XVIII. Erosion occasioned by overgrazing 

XIX. Phenomena incidental to overgrazing ...................... . 

. XX. The piedmont deposit of the Yuba 

XXI. Barrier No. 1, Yuba River ...... . 

XXII. Aspects of debris at barrier No. 1, 

Yuba River .................. . 

XXIII. Map of the bed of Yuba River in 

October, 1905 ................ . 

XXIV. Map of the bed of Yuba River in 

October, 1906 ................ . 

XXV. Erosion below barrier No.1, Yuba 

River, resulting from deposition 

above the bar.rier .............. . 

XXVI. Brush and log dams for storage of 

hydraulic-mining debris ....... . 

XXVII. Crib dam for storage of hydraulicmining debris ................ . 

XXVIII. A delta marsh bordering San Joaquin River ................... . 

XXIX. Tidal marshes ................... . 

XXX. Observations of midstream velocity of current in the Golden 

Gate September 12-13, 1914 .... 

XXXI. Observations of midstream velocity of current in the Golden 

Gate September 19, 1914 ...... . 

Page. Page. 

PLATE XXXII. Water stages, velocities,. and dis12 charges in Ravenswood Slough 

· · ...... ·september 25, 1914: .. ~......... 124 

13 XXXIII. Water stage, velocities, and dis18 charges in Ravenswood Slough 

19 November 16-17, 1914.'........ 124 

26 XXXIV. Relation of storage of tidal water 

by Ravenswood mar8h to rise 

26 and fall of tide at observation 

station near mouth of Ravens26 wood Slough ........... ~....... 130 

FIGURE 1. Flood basins 'of Sacramento Valley 

27 and the Sacramento-San Joaquin 

delta.............................. 14 

2. Distribution of data bearing on subsi28 dence.... .......................... 18 

29 3. Observed relations of land and sea 

42 level ................ :............. 20 

4. Fluctuations of low-water level due 

42 mainly to the deposition of mining 

debris on river beds and its subse42 quent erosion...................... 30 

5. Graphic statement of factors controlling 

43 estimation of deposition in bays and 

44 strait for periods not covered by 

44 measurements....................... 36 

44 6. Outline map of the piedmont deposit of 

45 Yuba River .................. ·....... 52 

7. Diagrammatic longitudinal section at 

46 barrier No. 1, Yuba River, illustrat52 ing the relation between fill above 

52 · the barrier and scour below it..~. . . . 59 

8.' Position and form of the low-water 

53 channel of Yuba River from Smartsville narrows to Parks Bar Bridge :ln 

58 different years ............. :........ 61 

9. Outline of the major levee system 

58 adopted for control of floods in Sacramento Valley....................... 66 

10. Configuration of the bottom in the 

60 Golden Gate and on the Golden Gate 

bar:............................... 70 

66 11. Ideal section of effective tidal prism in 

a large bay ........... ·. . . . . . . . . . . . . . 71 

67 12. Ideal section of effective tidal prism in 

a long estuary. . . . . . . . . . . . . . . . . . . . . . 72 

74 13. Cotidallines in the San Francisco Bay 

75 system................. . . . . . . . . . . . . . 72 

14. Profiles of tidal range along the line of 

the main channel from the Golden 

116 GatP- bar to Sacramen~o.............. 74 

15. Marsh lands and bodies of open water 

affecting the tidal volume at Golden 

116 Gate bar..... . . . . . . . . . . . . . . . . . . . . . . 76 

5 
6 ILLUSTRATIONS. 

FIGURE 16. Curves showing progressive variations 

of discharge in a channel serving a 

tidal marsh ....... " ............... . 

17. Diagram illustrating the relative efficiency of large and small tides for the 

transportation of debris ............. . 

18. Sequence and relation of tides and currents in San Francisco Bay when the 

moon is far above or below the plane 

of the earth's equator ............... . 

19. Diagrammatic section of a shore in San 

Francisco Bay, to illustrate the relation which structures that invade the 

water bear to the effective tidal 

prism ............................. . 

20. Miniature sand bar in Evolution Lake, 

SierraN evada, illustrating the mode 

of origin of the Golden Gate bar ... . 

21. The narrows of the Golden Gate ...... . 

22. Diagram to illustrate the influence of 

discharge from rivers on tidal currents in the Golden Gate .......... . 

23. Map of Ravenswood Slough and marsh. 

24. Cross profile of Ravenswood Slough at 

station for observations ............. . 

Page. 

FIGURE 25. Velocities at two points in the same section of. Ravenswood Slough ........ . 

77 26. Curves showing variation of ebb discharge at entrance of a tide marsh 

during a tidal period ................ . 

79 27. Curves showing variation of flood discharge at entrance of a tide marsh duiing a tidal period ................... . 

28. Relation of tidal storage in Ravenswood 

80 marsh to wa~er stage at the Presidio 

wharf. ............................ . 

29. Diagram used in estimating the lag of 

slack water after high water.and low 

water at entrances to the sloughs that 

85 serve tide marshes ....... ~ .......... . 

30. Plan of the Golde.n Gate bar .......... . 

31. Generalized cross profiles of the Golden 

96 Gate bar in its middle division ..... . 

109 32. Longitudinal profiles of. the Golden 

Gate bar in 1873 and 1900 .......... . 

33. Plan showing positions of the crest of the 

119 Golden Gate bar in 1855, 1873, and 

123 1900 .............................. . 

124 

Page. 

125 

128 

128 

134 

138 

140 

142 

144 

145 
PREFACE. 

The principal field work of this investigation its officers toward research and the high qualwas performed in the years 1905 to 1908. The ity of its library and library administration. 

pri1U:nry motive of the study was economic, The. United States Coast and Geodetic Survey 

a,nd for this renson especially a prompt report not only gave me free access to original records. 

of the results should ha,ve been submitted, but a,nd other archives but promoted my inquiries 

the a,ctua,l long delay wa,s ca,used by illness. through the cooperation of its experts. My 

After some progress ha,d been made in the study of tidal volume and tidal currents has in 

prepnration of this paper, I found great need particular been aided by the counsel and 

for the results of a laboratory study which -criticism of Dr. R. A. Harris, of that corps. 

ha,d been undertnken as ancillary to the field I have been aided by the United States Wenther 

work; a,nd the ma,nuscript wa,s laid aside until Bureau not only by special compilations of 

the lnborntory da,ta, could be discussed. 1 Dur- statistical material but through inquiries made 

ing the period of delny some supplementary nt my request by·its station officers. A special 

field -\vork ha,s been done-in the summer of study of tidal currents in the Golden .Gate 

. 1909 by Mr. W. D. Johnson, in 1910 by Mr. was made possible by the efficient ·cooperation 

W. C. Mendenhall, in 1913 by Mr. A. M. of the Lighthouse Service and of the Board of 

Gilbert, a,nd in 1913 and 1914 by me. Engineers for Rivers and ·Harbors at San 

In 1907 I wa,s a,ssisted in field work by Mr. Francisco. For facilities and assistance in the 

George Manship and in 1908 by Mr. H. S. Pond. study of sands I am indebted to the cui·ators 

Mr. S. K. Ba,ker, Mr. C. L. Nelson, Mr. E. C. of the United States National Museum and 

Murphy, 'Mr. N.C. Nelson, and Mr. R. C. Rice especially to :Mr. W. L. Schmitt. 

a,lso aided me by independent pieces of field The manuscript has had the advnntage of a 

work, the results of which are reported in other critical reading by Mr. C. E. Grunsky, Eng. D. 

places. Through the interlocking of subjects my 

In a few locnlities I encountered an atmos- nttention has been drawn to matters app~rently 

phere of secrecy in regard to mining opera,- remote from problems of mining debris. 

tions-a secrecy possibly indicative of illicit Mining debris merged, both bodily and in its 

hydraulicking-but the mine owners and the effects, with debris sent to the streams by 

mining community as a class gave cordial aid ·agriculture and other industries; the aggravato my work. I am especially indebted to Mr. tion of valley floods due to the clogging of 

W. B. Bourn and Mr. W. G. Shand for facilities channels by debris was inseparable from the 

in visiting a group. of high-level reservoirs and aggravation due to the exclusion of floods from 

to Mr. W. W. Waggoner and Mr. W. T. Ellis lands reclaimed for agriculture; ·the weakening 

for the generous contribution of records and of tidal currents at the Golden Gate by the 

other information. deposition of debris in the bays is inseparable 

Having my hendquarters for a long period in from the weakening .by the reclamation of tide 

Berkeley, Cal., I wa,s able to appreciate the lands; and the attention given to these co~­

hospitality of the University of Californi~ and lateral subjects has not only delayed the com1 Gilbert, G. K., The transportation of debris by running water, based 

on experiments made with the assistance of E. C. Murphy: U.S. Geol. 

Survey Prof. Paper 86, 1914. 

pletion of the report but has added materially 

to its volume. 

7 
.ABSTRACT. 

Chapter I. -Historical outline of the development of hydraulic mining in the Sierra 

Nevada, the encroachment of its tailings on 

valley lands, its subsequent restriction and 

regulation, and the circumstances leading to 

a study of the subject by the Geological Survey. 

Chapter II. -Physical features of the northern part of the Great· Valley of California. 

Sacramento and Feather rivers are bordered 

by natural 'levees which separate their channels 

from lateral basins of exceptional magnitude. 

Flood waters received by these basins are returned gradually to their channels, which are 

too small for the prompt conveyance of ·the 

flood discharges. The rivers have a large confluent delta, consjsting of marshes regularly 

flooded by tides and also subject to inundation 

when the rivers are in flood. 

·Chapter II I.-Subsidence of the land. In the 

region of the bays the .latest recorded crustal 

movement · has been. downward. Carquinez 

Strait and the Golden Gate are river gorges 

invaded by the sea, and the bays are submerged 

valley lands. The relations of tidal marshes 

to shore cliffs suggest that the downward movement has not yet ceased, and this view is. supported by the fact that certain shell mounds, 

the "kitchen refuse" of prehistoric vil.lages, 

stand below tide level. An attempt to demonstrate present-day subsidence by the study 

of tidal observations was not successful, but 

presumptive evidence of subsidence is afforded 

by certain changes in the outline of San Francisco Bay between 1858 and 1898. In the 

region of the river deltas subsidence is inferred, 

because the delta lands appear to be growing 

upward instead of extending hayward. 

Chapter IV.-The tailings from hydraulic 

mines were in part deposited on neighboring 

slopes and in neighboring stream valleys and 

canyons and in part delivered to rivers that 

carried them forward. At _the base of the 

range were large deposits on the piedmont 

slopes and other deposits in the beds of valley 

8 

rivers. As a consequence of the piedmont a~d 

river-bed deposits rivers rose higher in time of 

flood and lands previously immune were inundated. The reclamation of basin lands and 

delta lands for agriculture by surrounding them 

with levees also aggravated flood conditions, 

and the results of the two causes were inseparable. 

Chapter V.-The bays of the San Francisco 

system have been mapped, with soundings, 

more than once. Comparison of maps of early 

and late dates shows that large deposits have 

shoaled the bays and reduced their areas. 

These· deposits, ascribed to hydraulic mining 

and to the increase of soil waste by agriculture 

and other industries, have been measured for 

the periods between surveys and estimated for 

other periods; their total volume since the discovery of gold is more than 1,100 million cubic 

yards. 

Chapter VI.-As a basis for estimation of 

the volume of mining tailings .many hydraulicmining pits were surveyed .. The results were 

combined with measurements and estimates by 

others, with results of a study of soil waste in 

the Yuba River basin, with data on ·deposits in 

bays (Chapter V), and with results of a study 

of the detrital load of Yuba River (Chapter VII), 

and estimates were made of the volume of 

debris .moved in the basins of Sacramento and 

San Joaquin rivers as well as of its present 

distribution. 

Chapter VII.-(1) A barrier erected by the 

California Debris Commission arrested debris 

in transit along the bed of Yuba River. By 

means of surveys of the bed at three dates the 

arrested debris was measured; debris in suspension was also measured by means of water 

samples, and a discussion of the results gives an 

estimate of the normal detrital load of the river. 

(2) The water passing over the barrier was 

underloaded and therefore eroded the bed 

below the barrier. The erosion was measured. 

(3) A series of maps of the river bed above the 
ABSTRACT. 9 

barrier, made for various purposes, serve to 

illustrate the shifting of the deep channel 

from season to season. An explanation is suggested. (4) The response of the Yuba to 

engineering works at Daguerre Point illustrates 

further the adjustment of channel bed to detrital load. 

Chapter Vlll.-The fut~·e movements of 

debris in the river basins are discussed, with 

consideration of modification by engineering 

works for the restraint of debris of the Yuba 

and of modifications by the execution of the 

plan adopted for the control of flood waters in 

the Sacramento basin. 

Ol~apter JX.-Golden Gate bar lies outside 

the strait, its crest having a semicircular outline. Its position and the depth of water on 

its crest depend on the volume of tidal discharges tlll'ough the strait and on the volun1e 

of sand annually brought to the bar. The 

tidal volmne is affected by changes in progress 

in the bays. Deposits on shoals, encroachments on the areas of the bays, and the reclamation of bordering marsh lands reduce the tidal 

volume. The reclamation of delta lands affects 

the tidal volume but little. It is estimated that 

past changes have reduced the volume about 4 

per cent, and further reduction is to be expected. Surveys of the bar made by the 

United States Coast and Geodetic Survey in 

1855, 1873, and 1900 show a retreat of the crest 

toward the land but do not demonstrate a 

reduction of depth of water. The sand brought 

to the head of Suisun Bay by Sacramento and 

San Joaquin rivers is swept onward in the bays 

by tidal currents but is not believed to reach 

the bar in any appreciable quantity. 

Chapter X.-The stress which caused the restriction of hydraulic mining ilo longer exists. 

Under conditions to be created by works for 

the control of floods the capacity of valley 

rivers for transportation of debris will be increased, so that the mining might be partly resumed without prejudice to any valley interest 

except. navigation. The important interest 

which now dictates that debris should be controlled is that of the commerce which traverses 

the Golden Gate. Possibilities for resumption 

of mining on a large scale, with storage of debris, 

lie in cooperation with irrigation and electricpower development for the control of Sierra 

streams. 

' HYDRAULIC-MINING DEBRIS IN. THE SIERRA NEVADA. 

ByGROVE KARL GILBERT. 

CHAPTER I.-INTRODUCTION. 

In the early days of gold mining in the Sierra 

Nevada only a moderate amount of earth was 

disturbed. An arn1y of men were engaged, but 

they worked as laborers, with pick, shovel, and 

rocker. It was only gradually that more efficient methods were developed; but finally the 

resources of the engineer were brought to bear, 

water power was substituted for n1an power, 

and vast quantities of earth were handled. At 

the height of hydraulic mining, when hundreds 

of large jets of water were turned on the auriferous deposits, the material annually overturned was reckoned in scores of millions of 

cubic yards. 

The material thus washed from the hillsides 

consisted chiefly of sand and the finer detritus 

called" slickens," but included also much gravel 

and many cobbles and boulders. The slickens 

was taken in suspension by the water used in 

minip.g and went with it to the creeks and 

rivers. Much of it escaped from the mountains 

altogether and found eventual lodgment in the 

Great Valley of California or in the tidal waters 

of San Francisco Bay and its dependencies. 

The coarser stuff tarried by the way, building 

up alluvial deposits on the lower hill slopes, in 

the fiatter creek valleys, and in the river canyons. (See Pis. I, VI, and VII.) When rains 

and fioods came the sands and gravels were 

moved forward toward the lowlands, and in 

1862 a great flood washed so large a quantity 

into the lower reaches of the Sierra rivers· and 

. into the rivers of the Great Valley that the 

holders of riparian lands became alarmed. The 

mining-debris question, then for the first time 

generally recognized, assumed greater and 

greater importance and prominence in s·ubsequent years and led to protest and litigation 

which in 1884 culminated. in a series of injunctions whereby the miners were restrained from 

casting their tailings into the streams. The 

petitioners were valley dwellers, and the evils 

cited by them included the burial of alluvial 

farming lands by the flood of debris, the obstruction to navigation from shoaling of Sacramento and Feather rivers, and the raising of 

the flood levels of the valley streams whereby 

the area of periodic inundation was increased 

and protection against inundation became 

more difficult and expensive. · 

In connection with the litigation the subject 

was elaborately discussed, and the testimony 

included the evidence of a number of engineers 

who differed as widely in opinion as in point of 

view. Impartial and valuable investigations 

and reports were made by a series of officials 

and commissions at the instance of National 

and State gov'ernments. In 1880 the State engineer of California, William Ham. Hall, reported on the flow of mining detritus. 1 In the 

san1e year Lie~t. Col. George H. Mendell, 

Corps of Engineers, United States Army, was 

designated. to conduct a general investigation 

authorized by. Congress, and his preliminary 

and finalreportswere printed in 1881 and 1882.2 

In 1888 a commission constituted of three Arn1y 

engineers, Lieut. Col. W. H. H. Benyaurd, 

Maj. W. H. Heuer, and Maj. Thomas H. Handbury, began a still more extensive study, the 

report on which was printed in 1891.3 As an 

outcome of t4is discussion and especially of the 

report of the Benyaurd commission, a per1 California State Eng. Rept. to Legislature, sess. 1880, pt. 3, Sacramento, 1880. 

2 Mendell, G. H., Protection of the navigable waters of California from 

injury from the debris of mines: Chief Eng. U. S. Army Ann. Rept. 

for 1882, pt. 3, pp. 2543-2640; also in 47th Cong., 1st sess., Ex. Doc. 98. 

a Report o.f board of engineers on mining debris in the State of California: Chief Eng. U. S. Army Ann. Rept. for 1891, pt. 5, pp. 2996-3118; 

also in 51st Cong., 2d sess., Ex. Doc. 267. · 

11 
12 HYDRAULIC-MINING DEBRIS IN THE SIER.RA NEVADA. 

manent board, known as the California Debris 

Commission, was appointed in 1893, with authority under an act of Congress 1 to regulate 

hydraulic mining in such way as to prevent any 

injury to the navigable waters of Sacramento 

and San Joaquin rivers. Hydraulic mining 

was prohibited except as specifically licensed 

by the commission after inspection and approval of arrangements for the impounding of 

tailings. The commission was placed in charge 

Qf all works for the protection and improvement of navigation in those streams and was 

instructed to devise plans for the control of the 

movement of detritus in the rivers and their 

tributaries, with a v:iew to the general resumption of hydraulic mining without prejudice to 

other interests. "The constitutionality of such 

an enormous interference with the interior 

affairs of one of the States of the Union as was 

embraced in this law was based on the provision of the Constitution of the United States 

assigning to the Federal Government the duty 

of regulating the commerce between States and 

incidentally of protecting the navigable highways."2 Appropriations ·were afte:rWard made 

for impounding works to be erected under the 

direction of the commission, and the expense 

was equally divided between the National and 

State governments. The State of California 

appointed a debris commissioner· to cooperate 

with the national commission, and his reports/ 

as well as the reports of the conimission/ .con--

tinue the discussion of the debris· question. 

There is also a question of general control 

of the flood waters in the Sacramento River 

basin which is intimately connected. with the 

problem of mining debris, and . this likewise 

has been the subject of 'a series of investigations and reports. A plan submitted by the 

Debris Commission in 19115 has been adopted 

by the State legislature, 6 and a beginning has 

1 An act to create the California Debris Commission and regulate 

hydraulic mining in the State of California: U. S. Stat. L., vol. 27, 

pp. 507-511, 1893; ~!so in Chief Eng. U. S. Army Ann. Rept. for 1894, 

pt. 6, pp. 3184-3187. 

2 Harts, W. W., The control of hydraulic mining in California by the 

Federal Government: Am. Soc. Civil Eng. Proc., vol. 32, No.2, p. 98, 

1906. . 

· a Waggoner, W. W.-, Reports'ofthe debris commissioner, May 28,1901, 

to Dec. 1, 1902, Sacramento, 1903; Dec. 1, 1902, to Nov. 1, 1904, Sacramento, 1905; Nov. 1, 1904, to Dec. 31, 1906, Sacramento, 1907. 

4 The reports of the commission are contained in the annual reports 

of the Chief of Engineers, U. S. Army, from the year 1894. Those for 

1894, 1899, 1900, 1907, and 1911 are of special importance. 

5 62d Cong., 1st sess.;H .. R. Ex. Doc. 81. This report gives summaries 

of earlier plans for the same purpose. 

o California Stat., eh. 25, ~xtra sess., 1911. 

been made in its execution. It provides for 

great enlargement of the channel of Sacramento River near its mouth, and for a system 

of by-passes (p. 65) in. the middle part of its 

valley to supple~ent the river channel, which 

is there too small for t.he conveyance of the 

flood discharge; and it includes Government 

control of all plans for the construction of 

levees. 

Under licenses granted by the California 

Debris Commission a small amount of hydraulic mining has been carried on; but the 

available sites for economic impounding are 

few, and the experience of the first 10 years 

seemed to dem:onstrate that the great .deposits of auriferous gravel, in which the average content of gold per unit of volume is 

small, can not be .exploited with profit to the 

owners under such restrictions. Such restraining works as were erected by the commission on the main lines of the rivers did not 

succeed in controlling the movement of the 

debris ·which had been excavated in earlier 

years, and the published plans of the commission did not promise such comprehensive 

storage as· would rehabilitate the hydraulicmining industry. 

On December 8, 1904, the California Miners' 

Association adopted in convention the following memorial, which was forwarded to the 

President of the United States and by him referred to the United States Geological Survey: 7 

SAN FRANCisco, December 8, 1904. 

To the President of the United States, 

Washington, D. C.: 

Whereas the placer and hydraulic miner who onglnally developed the resources of Caiifornia and opened 

·them to the world obtained "title .from the Government 

of the United States to his placer lands with the common 

understanding that they w•ere to be worked and their gold 

contents recovered in accordance with methods of sluicing 

and hydraulic mining publicly known to have been devised and used for the purpose from the earliest stages of 

placer mining; 

Whereas many deposits of gold to the value of millions 

of dollars are now idly buried in the ancient river channels of California under such conditions that they can 

not be profitably worked either by dredging, by drifting, 

or by any other process than that of hydraulic mining; 

Whereas the gold extracted by the hydraulic miner 

was generously poured into the Treasury of the United 

7 The memorial was accompanied by a copy of an address by Prof. S. B. 

Christy on "Mining debris and natural sediment," which is printed in 

the proceedings of the Thirteenth Annual Convention of the California 

Miners' Association, pp. 137-156. 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE I 

A. A HYDRAULIC GOLD MINE. 

The water is conveyed by pipe, under a head of several hundred feet, and delivered through a nozzle that can be 

turned in any direction. The jet washes the auriferous earth from the cliff and thence to a sluice, seen at the left. 

The sluice is several hundred feet long and contains pockets of mercury by which the gold is caught. Photographed 

in 1908. 

B. A RIVER VALLEY FLOODED BY MINING DEBRIS. 

The locality is amon$ the foothills of the Sierra Nevada, and the estimated thickness of the deposit is 70 feet. Only coarse debris is lodged here; the finer part of the tailings has been carried farther. Photographed in 1908. 

I 

HYDRAULIC MINING AND MINING DEBRIS. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE II 

A. PENN VALLEY. 

One of a series of valleys lying among the hills that constitute the upland between the canyons of Yuba and Bear 

rivers. Some of the hills appear in the distance. 

B. CANYON OF MIDDLE FORK OF YUBA RIVER AT FREEMAN'S BRIDGE. 

Above the canyon wall is a rolling upland, and here the transition from one topographic type to the other is 

abrupt. 

TOPOGRAPHIC TYPES IN THE WESTERN PART OF THE SIERRA NEVADA. 
INTRODUCTION. 13 

States Governme,nt in the dark days of the Civil War 

when the national currency was worth less than 50 cents 

on the dollar, thus materially assisting in maintaining the 

credit of the Government and in saving the Union; 

Whereas the hydraulic miner has been restrained by, 

the United States courtS from discharging boulders, 

gnwel, sand, clay, and other matter in suspension into the 

navigable waters of the State, whereby the industry of 

hydraulic mining has been destroyed and property to 

the value of over $100,000,000 has been rendered idle and 

unproductive since 1884, the natural wealth of the State 

rendered unavailable, and a deadlock has resulted between the fundamental industries of agriculture and 

mining; 

Whereas while admitting the injurious effect of mining debris where not effectually restrained, the unavoidable effect of natural erosion and sedimentation has been 

ignored in the minds of the courts as well as of the farmers, 

and all the injury due to natural causes has been charged 

to hydraulic mining; 

'Whereas should hydraulic mining forever cease, to the 

injury of the miner, the natural process of erosion and 

sedimentation would still continue to the injury of the 

farmer and the navigable waters of the State; 

Whereas we are firmly convinced that by a rational 

application of the laws governing the deposition of sediment from torrential streams, the industries of hydraulic 

mining and agriculture can both be carried on in this 

region, not only without prejudice to each other but to 

their niutual advantage; and 

Whereas this question is primarily a geological one 

and can be solved only by geologists who have devoted 

their lives to the study of erosion and sedimentation, 'in 

mountain as well as in valley regions; therefore be it 

Resolved, By the. California Miners' Association, that 

·We beg you, as President of the United States, to assist in 

the solution of this problem affecting all the interests of a 

great Commonwealth, by instructing· the Director of the 

United States Geological Survey, through the Secretary 

of the Interior, as part of his study of the storage of flood 

waters and the reclamation of waste lands, to undertake a 

particitlar study of those portions of the Sacramento and 

San Joaquin valleys affected by the detritus from torrential streams. 

The points we wish particularly considered are: 

First. The most favorable sites for reservoirs for water, 

whereby destructive floods may be averted and the 

waters stored and utilized for the benefit of agriculture, 

111ining, and other industries. 

Second. The selection of suitable tracts of waste lands 

and of the most suitable means whereby the detritus from 

torrential streams may be deposited on such waste lands, 

so as to reclaim them and convert them gradually into 

lands suitable for forestry and other agricultural purposes, and at the same tiine to remove from such streams 

their burden of detritus so tha;t they may cease to be a 

menace to th.e navigable waters of the State. 

In view of the importance 9f this inquiry to the three 

great fundamental industries of agriculture, mining, and 

commerce, we beg that this inquiry be undertaken at the 

earliest opportunity and pushed to completion as rapidly 

as consistent with thoroughness. 

At the time of the presentation of this memorial the United States Geological Survey included as one of its branches the Reclamation 

Service, an organization specially equipped for 

the study of practical engineering problems 

connected with the control of surface waters, 

and this branch was ·intimately associated with 

the water-resources branch, which was devoted 

to statistical and scientific studies of the waters 

of the country. An investigation on the lines 

proposed by the memorial was accordingly arranged by the water-resources branch, but the 

present writer was detailed from the geologic 

branch because the study of the transportation 

of detritus by running water belongs to geology 

as well as to engineering. The investigation as 

planned included (1) a field study of the phenomena connected with the ''debris problem'' ; 

(2) a laboratory study of the laws of transport~tion of detritus by running water; and (3) 

an engineering study, for which no immediate 

provision was made. The separa:tion o-r the 

Reclamation Service, which was made an independent bureau of the Department of the Interior in 1906, removed from the Geological 

Survey the body of engineers specially selected to deal with the problems of construction for the control of rivers, and the specific 

engineering questions connected with the debris problem have not been adequately studied. 

The laboratory research, which has a bearing 

much broader than the local problem, has been 

.made the subject of a separate report. 1 

. The present report, which deals largely with 

geologic and physiographic aspects of the subject, is not restricted to the specific questions 

raised by the memorial of the California Miners' 

Association but takes account of various other 

factors. In order to consider the feasibility of 

a resumption of hydraulic mining_ in the Sierra 

Nevada, it traces the physical effects, past and 

future, of the hydraulic mining of earlier decades, the similar effects which certain other industries induce through stimulation of the 

erosion of the soil, and the influence of the restriction of the area of inundation by the construction of levees. Such constructive suggestion as it makes is in the direction of cooperation by .severalinterests for the control of the 

streams now carrying heavy loads of debris. 

1 Gilbert, G. K., The transportation of debris by running water, based 

on experiments made with the assistance of E. C. Murphy: U.S. Geol. 

Survey Prof. Paper 86, 1914. 
. CHAPTER !I.-NATURAL CONDITIONS OF. THE SACRAMENTO BASIN WITH 

RESPECT ESPECIALLY TO THE MOVEMENT OF DETRITUS AND THE 

REGIMEN OF RIVERS. 

The Great Valley of California lies between 

the Sierra Nevada on the east and the Coast 

Ranges on the west; at the north and south 

1..._0 ......................... a-.· _ _..·io __ 2_._o _ ____,30Miles 

FIGURE 1.-Flood basins of Sacramento Valley and the SacramentoSan Joaquin delta. 

mountains close in about its ends. Midway of 

its length the Coast Ranges are divided by an 

arm of the sea comprising San Francisco, San 

14 

Pablo, and Suisun bays, and this arm receives 

Sacramento and San Joaquin rivers, which 

drain the valley. Northward from Suisun Bay 

for more than 100 miles the valley has a width 

of 30 to 40 miles; farther north it is narrower 

and of differ(3nt habit. In the broader part 

three belts may be distinguished-on the east. 

an alluvial slope descending fron1 the foothills 

·of the Sierra, on the west an alluvial slope 

descending from the Coast Ranges, and between. 

these two a flatter lowland which is inundated 

annually by the flood waters of the rivers. 

Through the belt of periodic inundation runs 

the trunk river-the Sacramento-bordered on 

each side by a raised bank or natural levee 

which stands higher than the inundated land 

beyond but is itself submerged at :extreme 

flood. The lowlan.ds thus partitioned from the 

river are appropriately called basins. Feather 

River, which joins the Sacramento midway in 

the valley, has the same habit for the lower 25 

miles of its course. The inundated belt east of 

the Feather and Sacramento is divided into 

three parts by the alluvial plains of Yuba and 

American rivers, and those strean1s discharge 

directly to the trunk rivers. The minor strea1ns 

. from east and west deliver their waters to lateral basins. The arrangement of the basins is 

shown in figure 1. 

Such entrainment of a river between banks 

of its own building and such flanking by lowlands periodically inundated are features of 

the depositional phase of a stream when and 

where the material brought for deposit is so 

fine as to be carried in suspension. They are 

most frequently found near the mouths of long 

rivers but may occur also at other points where, 

for any reason, the stream is engaged in deposition instead of erosion. 

Along the ·lower course of the Sacramento 

the phase just described merges into a delta 

phase. The lateral inundated tract assumes 

.the character of a permanent marsh, the water 

level of which oscillates regularly with the 

tides. The natural levees become lower. The 
NATURAL CONDITIONS OF THE SACRAMENTO BASIN. 15 

channel divides, giving to parts of the marsh 

lands the chn.racter of islands, and some of its 

divisions connect with t}:le channels of other 

rivers. 'rho delta n1arsh of the Sacramento is 

continuous with thedeltamarshes of the Mokelunlne and the San Joaquin, so that much of it 

may be inundated by a flood of either river. 

The Sierra Nevada is a broad range, whose 

crest line is near the eastern edge and whose 

nltitude gradually decreases frmn east to west. 

A belt near the crest line was occupied by glaciers during the ice age, with the result th~tt 

its surface now has much bare rock, many lake 

bnsins, and little ground suited for the growth 

of forests. In this region precipitation is 

heavy, and winter snow banks store water for 

the sumn1er flow of the streams. The larger 

rivers heading in this upper region traverse 

the n1iddle apd lower belts of the range in steepwalled canyons, and before the advent of the 

white nutn the streams at nearly all points 

rested on the rock bott01ns of the canyons and 

were engaged in deepening them. Between 

the rivers there are in places upland valleys a 

thousand feet higher than the ca~yon bottoms 

(Pl. II), and creeks traversing these valleys 

were comparatively sluggish, their slopes, like 

those of the adjacent lands, being gentle. On 

leaving the valleys the creeks tumbled rapidly 

through short gorges down to the rivers. The 

rivers continued to the western base of the 

range with steep descent and rocky beds, but 

at the bn.se their habit was abruptly changed, 

the slopes of the beds becoming gentl~ and the 

1naterial of the beds changing to gravel and 

sn . .nd. As they approached the trunk rivers 

of the valley their grades beca1ne still flatter 

and the visible 1naterials of their beds became 

finer. 

During the low st~ges of sum1ner and autmnn th0 Sacramento and other rivers of the 

valley were confined to their channels and 

their waters were clear; the borderuig basins 

were either empty or partly occupied by 

swmnps with a growth of rushes. In its lowru: 

7Il3tl 0 -l7-2 

course the Sacramento carried deep, slack water with a conspicuous tide extending to Sacramento, 62 n1iles north, and a less notable 

tide to the mouth of the Feather, 20 miles farther north. In the early days seagoing vessels 

ascended regularly to Sacramento and occasionally to :Marysville, on the Feather. 

In tin1es of flood the waters regularly overtopped the banks and filled .. the adjacent basins, 

through which they moved slowly and frmn 

which they. drained gradually back to the main. 

channel as the flood subsided. The detrital 

load. of the flood was spread by them over the 

whole inundated tract, including the delta 

marshes, which acted as a systmn of settling 

basins. Some of the coarser silt was added to 

the natural levees, maintaining them at an 

adjusted height, and as these depended for 

their existence on such deposition they could 

never rise above the highest floods. Such of 

them as now remain unn1odified serve to record 

the level of flood waters in those early times. 

A portion of the suspended load carried forward by the swifter current of the main channel found its way through the mouth of the 

river and came to rest in the bays beyond, but 

it is probable that the principal portion was 

received by theinundated lands. 

The lateral basins affected the channel characters in important ways. They conveyed a 

large part of the flood discharge and thus left 

for adjacent portions of the channel only a 

small part. They acted as reservoirs for the 

storage of flood waters and fed them gradually 

to the lower course of the Sacramento, so that 

the channels in the delta region were only moderately taxed by the floods. The channels in 

consequence. were adjusted for the conveyance 

of only a fraction· of the flood discharge; they 

were of moderate section and their meand~l'S 

were of small radius. Between the town of 

Colusa and the mouth of Feather River the 

channel of Sacramento River grows gradually 

smaller downstream until its estimated capacity 

is only 10 per cent. of th.e flood discharge. 
CHAPTER III.-SUBSIDENCE OF THE LAND. 

There is some reason to think that the areas 

in which the mining and other debris ~omes 

finally to rest are undergoing a slow downward 

movement. Such a movement would tend to 

diminish the injurious influence imposed on 

various industries by the deposition of the 

debris. Mter a review of the evidence I am 

satisfied that the possible economic significance of land subsidence is limited to San 

Francisco Bay, so that the subject might with 

propriety receive only scant attention in this 

paper, but as a negative result has a value of 

its own, space will be given to such evidence as 

has been assembled. . 

Lawson/ in two important papers, discussed 

movements of elevation and subsidence in the 

coastal regions of California in the later geologic periods. Some of the movements affected 

large areas with approximate uniformity. 

Others affected adjacent areas very differently. 

We are here concerned with the latest movements, because the latest are most likely to continue in progress at the present time. On parts 

of the coast near the Golden Gate the latest 

recorded movement was downward and involved about 80 miles of the coast. The. evidence of the change consists chiefly in the occupation by tidal water of hollows that are shown 

by their forms to have been shaped by streams 

on the land. The subsidence was greatest at 

the Golden Gate, where its approximate measure is the depth of the strait, 378 feet, and its 

ainoun t diminished in both directions along the 

coast. Before the subsidence the Golden Gate 

passage was the lower gorge of Sacramento 

River, and the basin now occupied by San 

Francisco Bay was a valley with gentle allu-

. vial slopes crossed obliquely by Sacramento 

River. That basin is part of a long, straight 

structural trough extending many miles southeastward; and the down warping of the trough 

that created the bay was accompanied by a 

gentle upwarping farther south. This diver1 Lawson, A. C., The post-Pliocene diastrophism of the coast of southern California: California Univ. Dept. Geology Bull., vol. 1, No.4, pp. 

115-160, 1893; The geomorphogeny of the coast of northern California: 

ld m, No.8, pp. 241-272, 1894. 

16 

sity of associated movements serves to put us 

on our guard against the assumption of uniformity of change in contiguous areas. 

The basins o£ San Pablo and Suisun bays and 

Carquinez Strait, by which they are connected, 

have a general resemblance tq the San Franci~co basin and the Golden Gate, and the most 

salient facts of their recent history are the 

same. Subsidence has created bays where 

previously there were open valleys and has 

produced a tidal strait where once there was a 

river gorge. Certain details of their history, 

however, are different: 

Trask,Z who visited the region in 1853, observed" a littoral seabeach, having an elevation 

of about 30 feet above high tides" and "composed of fragmentary and entire shells mixed 

with a little sand and clay." It was visible as 

"a distant white line" for 8 miles on the north 

shore of San Pablo Bay and also at Benicia. 

Newberry, 3 a few years later, described a similar feature, 20 feet above sea level, on the south 

shore of the same bay. Both geologists inferred a recent uplift of the land, and Newberry 

noted that the uplift was riot shared by the 

basin of San Francisco Bay. The terraces have 

been observed more fully by A. C. Lawson, and 

I am permitted to quote some of his unpublished results, communicated in a letter: 

On the ea.st side of San Pablo Bay, between Pinole 

Point and Mare Island, there are terraces ranging from 12 

to 30 feet above the sea level, and these extend in remnants into the Carquinez Strait. These terraces are in 

many places characterized by an abundance of marine 

shells, such as oysters and pectens; the terrace on Mare 

Island is a particularly distinct wave-cut feature. On the 

stretch of country between Pinole Point and Vallejo Junction the same shells that characterize the surface of the 

terraces in other places exist beneath a rather heavy 

mantle of later Quaternary alluvium about 100 feet thick, 

containing numerous remains of the Equus fauna. 

Both the terrace with its marine shells and the overlying alluvium have been dissected to a level below the 

prese~t tide, and the valleys due to such dissection are 

drowned to a moderate extent. 

2 Trask, J. B., Report on the geology of the Coast Mountains and part 

of the Sierra Nevada, p. 27, 1854. 

s Newberry, J. S., U.S. Pacific R. R. Expl., vol. 6, pt. 2, p. 14, 1857. 
SUBSIDENCE OF THE LAND. 17 

N. C. Nelson, of whose observations further 

mention will be made, noted a terrace near 

Antioch, with similar dissection by streams 

and with invasion of the stream valleys by 

tidewater and tidal marshes. The height of 

the terrace plain is about 25 feet at its outer 

edge, bordering San Joaquin River, and increases to about 50 feet at the base of the 

Mount Diablo foothills, which rise abruptly 

from its southern margin. 

The· presence of these terraces shows that 

the history of recent change has not been the 

same in the eastern area as in the basin or' San 

Francisco Bay, but the character of the dissection of the terraces indicates th~t here also 

the latest recorded movement was downward. 

The local series of changes since Sacramento 

River excavated the Carquinez gorge includes, 

first, a subsidence of more than 100 feet; 

second, an elevation of more than 50 feet; and 

third; a subsidence of about 30 feet. 

The two areas of unlike history do not merge 

at their common boundary but are sharply 

separated by one of the master faults of the 

region, the Haywarc;ls fault. This fault is 

characterized along its line of outcrop by 

peculiar topographic features-rift featureswhich California geologists have learned to 

recognize as indicative of differential movement in very recent times; and a portion of 

the fault near fiaywards was in fact the focus 

or origin of a notable earthquake in 1868. 

The rift has been traced along the southwestern 

face of the Berkeley Hills to Pinole Point and 

also along the northeastern edge of Petaluma 

Valley. The fault therefore crosses San Pablo 

Bay in a northwesterly direction. (See fig. 2.) 

The basin of the western division of this bay, 

which is' slightly smaller than the eastern, belongs to the same crustal block as the basin of 

San Francisco Bay and apparently shares its 

history of recent subsidence. The block that 

holds the basin of the eastern division appears 

to extend eastward to the line separating the 

Coast Ranges from the Great Valley of California, and through this spaqe the recent movem,ents of elevation and subsidence have been 

harmonious. 

Because the latest determined movement in 

the two areas was downward it does not necessarily follow that subsidence is now in progress, 

for the movement may have ceased, and· it is 

not always easy to discriminate from physiographic data between a subsidence in progress 

and a subsidence completed. In the present 

case, however, the evidence is more than 

usually satisfactory. Many arms of the bays 

are occupied or partly occupied by tidal 

marshes-level tracts which are submerged 

only at high tide. . Parts of the coast fringed 

by such marshes are protected from the action 

of waves, but other parts are exposed to wave 

attack. The exposed parts have been eroded 

by the waves and shore cliffs have been developed, but similar cliffs do not appear where the 

marshes protect the coast. (See Pl. III.) The 

plains occupied by the marshes are not plains 

of the original pre-subsidence topography but 

have been built up in the water. They are 

composed of mud brought in suspension and 

distributed by the tides and of the decayed 

remains of marsh vegetation. Had the subsidence taken place rapidly and reached completion before the building of the marsh lands 

the waves would have made their record on 

the coastal slopes, and that record would now 

be visible. From its absence I infer that subsidence was so slow that the building of marsh 

lands kept pace with it and the cliffless coasts 

were thus continuously protected. 

Another change continuously in progress has 

been the deposition of debris brought to the 

bay by streams from neighboring hills. The 

finer part has been distributed by tidal currents 

and has helped to build the marsh plains. The 

coarser material has been arrested at the·creek 

mouths, and its deposition has tended and still 

tends to build deltas with subaerial slopes. 

The actual construction of deltas above tide 

level depends on the relation of the supply of 

delta material to the rate of subsidence. With 

cessation ·of subsidence the deltas would be 

extended on· the marsh plain. The development of deltas is in reality small, as it ·should 

be if subsidence is still in progress. 

The features just described have been studied in a systematic way only on that part of the 

west coast of San Francisco Bay which lies 

north of the Golden Gate. They have been 

noted elsewhere from car windows and have . 

been inferred from the topographic details. of 

Coast and .Geodetic Survey charts of San Pablo 

and Suisun bays and from large-scale maps by 

the Geological Survey covering the eastern part 
18 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

of Suisun Bay and the mouths of Sacramento 

and San Joaquin rivers. They serve to show 

that the subsidence which constitutes the latest 

of the known geologic movements has contin-

) 

The presumption thus established is supported by archeologic data. All about the 

shores of San Francisco and San Pablo bays are 

shell mounds, the prehistoric kitchen middens 

/ / 

/ 

~ 0 ) 

r/ (I) 

\ 

' c+ 

' \ Q) 

Montezuma \ 

\ 

Hills I 

I 

I 

/ / 

FIGURE 2.-Distribution of .data bearing on subsidence. The dotted area is that in which dunes occur; circles show shell mounds now 

within reach oftide\vater or ~aves;· III_.::A, nr:.:B, IV-A, IV-B, indicate localities shown in Pls. III and IV; P, the Presidio; S, Sausalito; 

'- T, localities of t~:w:3a-root. terrace. · · · · · · 

uecl so nea~ly to .. the present time as·, to ~stablish 

a presumption· that it is still in progre_ss. And 

they show that~ ··the gep.eral rate of subsidence 

is no more rapid: than th'at of the upward growth 

of the marsh lands. 

of the regi.on. These mounds have been 

~apped ariel a scientific investigation of them 

has l;>een begun under the direction of .John C. 

Mertiam. It has been shown by excavation 

that three of them have their bases below water 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE III 

A. RICHARDSON BAY, AN ARM OF SAN FRANCISCO BAY. 

This is a typical "drowned valley"-that is, it is a valley shaped by streams as part of a land surface and afterward 

depressed, alon~ with the bordering hills, so as to admit the water of the ocean. The hilltops now make capes and islands, ana each salient point has been eroded by the waves so as to end in a cliff. The head of the bay 

and some of the lateral coves are occupied by tidal marshes. 

B. EMBAYMENT DIRECTLY NORTH OF RICHARDSON BAY. 

Almost wholly occupied by a marsh. The view was taken at low tide. At high tide the marsh is covered by water, 

but the water is shallow and its waves are feeble. They make no attack on the spur that descends from the hill 

at the right, and the spur retains its original form without erosion. 

FEATURES ILLUSTRATI G SUBSIDENCE. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE IV 

A. REMNANT OF A SHELL HEAP ON BROOKS ISLAND, SAN FRANCISCO BAY. 

Prehistoric inhabitants, living near the shore and using shellfish as food, accumulated shells and other refuse on their 

sloping village site until the deposit had a depth of about 20 feet. Owing to subsidence of the land the base of 

the heap is now 15 feet below high-tide level, and a portion has been washed away by the waves. Photograph by N.C. Nelson, 1907 . . 

B. A WIND-FORMED SAND HILL ON BRADFORD ISLAND, SAN JOAQUIN DELTA. 

The island was originally a tidal marsh and has been converted to "tule land" by levees and drainage. The peaty 

soil surrounds the sand hill and must have been accumulated after the formation of the hill. The sandy plain 

that presumably supplied the material of this hill now lies at too low a level to be reached by wind. Photograph by N. C. NelSon, 1908. 

FEATURES ILLUSTRATING SUBSIDE rcE. 
I. 

SUBSIDENCE OF THE LAND. 19 

level, and the partial sub1nergence of seven 

others is inferred fr01n their relation to marsh 

lands. As there is no reasonable doubt that 

the shellfish of which these piles are the refuse 

were consumed on land, the present relations 

show that subsidence has occurred since the 

advent of n1an to these shores. Nelson/ from 

whose recent publication the facts of distribution are taken, states that the greatest demonstrated subsidence is 18 feet. One of the 

n1ore striking examples is illustrated by 

J?late IV, A. . 

The ten mounds recorded as now standing on 

ground below tide level are all west of the Haywards fault, the most southerly being near the 

south end of San Francisco Bay and the most 

northerly on the Petaluma Marsh, north of San 

Pablo Bay. East of the fault are two which 

are believed to have been lowered fr01n their 

original position, because they are now so near 

the level of high tide that they may son1etimes 

be reached by storm waves. One is on the 

south shore of San Pablo Bay; the other on the 

north shore of Carquinez Strait. (See fig. 2.) 

The movement indicated by physiographic 

features and kitchen middens is evidently very 

slow-so slow that there need be no surprise 

that it has not attracted the attention of our 

own race during the brief period of our occupation. Where the tide has a range of several 

feet the mean water level is apprehended as a 

s01newhat indefinite matter; and even with 

regular observations of the tides the position 

of the 1nean level is not very a.ccurately deternlined unless exceptional precautions are taken. 

The only locality in the region where such work 

has been carried on with high precision is the 

Golden Gate. Tidal observations have been 

1nade there by the United States Coast and 

Geodetic Sm·vey since the beginning of its operations on the Pacific coast, and from the year 

1878 the work has been of adequate quality. 

From 1878 to 1897 the station was at Sausalito, 

on the north shore of the strait, and since 1897 

at the Presidio, on the south shore. 

The relative height of the zeros of the two 

stations was measured in 1897 by means of a 

series of si1nultaneous observations on the two 

gages. In 1906, a few 1nonths after the earthqun,ke of t~at year, a remeasurement was 1nade 

1 Nolson, N. C., Sholl mounds of the San Francisco Bay region: Cali· 

fomia Uni\T. Pubs. in Arch9ology and Ethnology, vol. 7, No. 4, pp. 

329-330, 1909. 

by means of the spirit level, the instrumental 

work being of the highest grade but involving 

sightings across the strait, at the great distance 

of 1.25 miles. The results from the two nleasurements, 1897 and 1906, differed by about 

0.13 foot. In the following discussion I have 

made use of the earlier measurement only, my 

preference being determined not by the belief 

that its method, considered as a· method of 

measuring vertical difference, is the more trustworthy but by considerations connected with 

the purpose of the discussion. If constant 

errors are involved in leveling from Sausalito to 

the Presidio through the water surface, the 

same errors are presumably involved in the 

comparison of determinations of mean sea level 

at the two points, and the use of the water-level 

measurement of the difference of zeros tends to 

eliminate the effect of such errors from the discussion; and if the localities of the two stations 

are affected differently by a progressive movement of the land, or were affected differently by 

disturbance at the time of the earthquake of 

April, 1906, the measurement made at the time 

of transfer of the tidal work is the one which 

avoids complication from such a cause. 

To aid my inquiry the Superintendent of the 

Coast and Geodetic Survey kindly had a separate determination· of mean sea level made 

from the observations ·of each year from 1878 

to 1913, excepting only the year of transfer, 

1897, when neither station was occupied for the 

entire year. The results of these computations 

are given in the following table: 

TABLE 1.-Height of mean tide above zero of United States 

Coast and Geodetic Survey tide gage at the Presidio, Cal., 

separately computed from the observations for each year. 

:Mean sea level. 

Year. Annual Five-year mean mean (feet). (feet). 

1878. 0 0 ••••••••• :. 0 ............. . 8. 73 . .......... 18790 0 0 ......................... . 8. 42 .............. 18800 0 0. 0 ....................... . 8. 51 8.53 

18810 0 0 ............ · ............. . 8. 55 8.48 

18820.0.0 ....................... . 8. 44 8. 55 

18830 00 0 ............... 0 ......... . 8. 49 8. 57 

18840 0 0. 0 ....................... . 8. 77 8.56 

18850 0 0 ...................... ; .. . 8. 62 8.55 

18860 0 0 0 ........................ . 8. 49 8.55 

1887 0 0 0 ....... 0 ... 0 ..... 0. 0 ..... . 8.40 8.51 

18880.0.0 ..................... 0 .. 8. 46 8. 52 

18890 0 .... 0. 0 ..... 0 ........... 0 .. 8.60 8.51 

18900 0 0 ... 0 ..... 0. 0. 0. 0 ... 0 .. 0 0 .. 8. 65 8. 50 
20 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

TABLE I.-Height of mean tide above zero of United States 

Coast and Geodetic Survey tide gage at the Presidio, Cal., 

separately computedfrom the observations for each yearContinued. · 

Mean sea level. 

Year. Annual Five-year mean mean (feet). (feet).a 

1891 ............................ . 8.43 8. 50 

1892 ............................ . 8.35 8.45 

1893 ............................ . 8.45 8.44 

1894 ............................. · 8. 39 8.47 

1895 ............................ . 8.59 a 8. 49 

1896 ............................ . 8. 57 a 8. 46 

1897 ............................ . [8. 47] a 8. 47 

1898 ............................ . 8.30 a 8. 46 

1899 ............................ . 8.44 a 8. 43 

1900 .......................... -·~. 8.50 8.45 

i901 ............................ . 8.46 8.50 

1902 ............................ . 8.57 8. 54 

1903 ...................... · ...... . 8.53 8. 57 

1904 ............................ . 8. 63 8.60 

1905 ............................ . 8. 65 8. 62 

1906 ............................ . 8.60 8.60 

1907 ............................ . 8.68 8. 57 

1908 ............................ . 8.44 8. 53 

1909 ............................ . 8.50 8. 56 

1910 ............................ . 8.43 8.50 

1911 ............................ . 8.64 8.51 

1912 ... ~ ........................ . 8.49 ............. 

1913 ............................ . 8.50 . .......... 

a The five-year means for 1895-1899 are derived by aid of tho interpo- lated annual moan for 1897. 

The observed relations of land and sea level 

are shown in figure 3. They are expressed in 

feet and are reckoned from an arbitrary datum, 

Feet 

8.3 

8.4 

I 8.5 

8.6 

8.7 

1

8.4 

n 8.5 

8.6 

l 0.1 

m .o 

-0.1 

0 

CX) 

CX) 

-

(\ " 

t.n 

·co 

CXl 

-

1\ 

0 

en 

CX) 

-

A 

t.n 

IT) 

CXl 

-

f v\ 

I rv \ 1/ \ 1/ ) 

I \I "\ 

I v 

8 

en 

-

!\ 

I \ V\ 

Y\ 

t.n 

0 

en 

- 0 

0) 

-

(\/ 

I \I "0 \., \j v Q) 

1.. C]) 

ce i 

10 C/) :> c 0" <d £ 

/'- +' ,._ 1.. A 

,.._..., 1\.. 10 

\....-v- Q) "" 'QI) /'1 

0 

\ _,... - ~ 

"\...- ~ 

FIGURE 3.-0bscrved relations of land and sea level. I, Annual means 

of tidal observations at the Golden Gate; II, five-year means of tidal 

observations at the Golden Gate; III, deviations of atmospheric 

pressure at San Francisco from the normal, expressed in terms of balancing column of water. 

the zero of the present tide gage at the ·Presidio. In the diagram. the scale of feet is intentionally inverted. If it were erect each upward inflection of the curve would express an 

apparent rise of mean sea level, on the assumption that the land is stable. With the inver .. 

sion, each upward inflection may be thought 

of as expressing an apparent rise of the land, 

o~ the assumption that mean sea level is 

stable; and as this assumption is actually 

made, the inverted curve presents the data in 

form convenient for inspection. 

The curve exhibits a general ~endency, at 

first upward, then downward; but this is 

largely masked by fluctuations of large amplitude and short period. Preconceptions which 

I believe well founded discountenance the 

view that these fluctuations, which attain 0.3 

foot, can be ascribed either to the· land on 

which the gages stood or to the general mean 

level of the ocean. They must have some 

adventitious cause. It has occurred to me 

that they might be in part systematic errors of 

observation, changing with change of observer 

and with modifications of the mode of observation; but I have no data by which to test 

this possibility. It has. occurred to me also 

that they may be due· to actual fluctuations of 

the local (as distinguished from the general) 

sea plane occasioned by variations in the annual 

mean of atmospheric pressure, or by variation 

in the mean of wind effects in pushing water 

toward or away from the coast. Through the· 

courtesy of the· United States Weather Bureau 

I have been furnished the means of air pressure 

at San Francisco from 1878 to 1908, except 

only 1906, when the record was interrupted; 

and these means, originally expressed in 

terms of balancing columns of mercury, I have 

converted into deviations from normal of the 

equivalent balancing column of sea water. 

'rhus converted they are strictly comparable 

with the me~ns of sea level and they have 

been plotted in figure 3. Their· range is so 

small that they manifestly fail to explain the 

fluctuations of the tidal means.1 The wind 

effect is less easily evaluated and its comparison has not been attempted. 

On the assumption that the apparent rapid 

fluctuation of the vertical relation of land at 

the Golden Gate to the great standard of reference, normal sea level, belongs to the general 

category of imperfect observation, it is in 

order to reduce its effect by smoothing the 

1 The recorded air-pressure means have a lower average before 1890 than 

afterward. This difference is not believed to represent a fact of nature 

but to be connected with the removal of the observing station to a new 

site or with some other accident of observation. 
I I 

SUBSIDENCE OF THE LAND. 21 

observational curve. This has been done by 

substituting five-year means for annual means, 

and the result is plotted in the middle line of 

figure 3. The general features of the smoothed 

curve include (1) a small and somewhat 

doubtful descent, (2) a slow, well-marked 

ascent, (3) a comparatively rapid descent, also 

well marked, and (4) an ascent. The total 

ascent from ahout 1883 to about 1899 is 0.14 

foot; the descent to about 190q is 0.19 foot. 

The mean for the first 10 years of observation, 

1878-1887, is nearly identical with the mean 

for the last 10 years, 1904-1913. 

The change from well-marked ascent to wellmarked descent coincides approximately with 

the transfer of the observations from Sausalito 

to the Presidio, and this fact suggests that 

crustal movements at the two points are not 

the same. The change frmn well-marked and 

nearly uniform descent to a slower ascent coincides approximately with the occurrence of the 

earthquake of 1906, which had its origin in the 

San Andreas fault, 7 miles west of the Presidio; 

and this fact suggests that slow movements of 

the crust recorded by the tide gage are intimately related to the sudden movements which 

cause sensible jars. Both these suggestions appear to me plausible. The warping implied by 

diversity of movement between points on opposite shores of the Golden Gate does not differ 

in kind from the warping of the trough of San 

Francisco Bay, described by Lawson. And the 

intimate relation between slow crustal movements and the strains relieved by earthquakes 

is a thesis ·of modern seismology. 

Though the evidence given by the gage records is not so harmonious as to be beyond question, it appears to me pr9bable that the progre$sive movements of the land indicated by 

the smoothed curve in figure 3 were actual, that 

the land about the Golden Gate, and also the 

land of a large including region, is in a state of 

unrest, its movements being part of the same 

general system of crustal change to which the 

modern faults and earthquakes belong. The 

record ~s too short to demonstrate a tendency 

toward subsidence or elevation, but the fact of 

unrest is harmonious with the idea that subsidence continues to the present time. 

Another piece of evidence is connected with 

the boundaries between tidal marshes and the 

open water of the bays. Those boundaries 

have been twice mapped with care, and a comparison of charts shows that changes have occurred. About Suisun and San Pablo bays the 

marsh lands have grown at the expense of the 

open water, the growth being closely associated 

with the deposition of mining debris on the 

shoals, and there are places where marsh lands 

have encroached on the water of San Francisco 

Bay. But there are also long stretches of the 

San Franciscan coast, stretches with an aggregate length of 18 miles, in which the marsh front 

has retreated. It is true that the marsh edge 

is not everywhere a well-defined and unmistakable line and that its mapping involves questions of interpretation (see Chapter IX), but as 

to the· general fact of wave encroachment there 

can be no question, for the erosion of the marsh 

front has opened new outlets for marsh waters 

and thus caused new tide channels to be scoured 

out and old channels to be silted up. A conspicuous example of this is found in the history 

of San Mateo Slough. In 1858 the mouth of 

the slough was at a point about 1 mile west of 

Guano Island, and a bend of the slough approached the coast at a point three-quarters of 

a mile farther west. The bend was then separated from the open water by a strip of marsh 

1,000 feet wide. By 1898 the coast had retreated so far that the slough communicated 

with the bay at the bend, and a new mouth 

had been established at that point, the old 

mouth having become ·so nearly obsolete as to 

carry no water at low stages of tide. Examples 

of similar character are afforded by Mountain 

View Slough, Newark Slough, and Guadalupe 

River; and a change in the mouth of Ravenswood Slough that had been barely initiated in 

-1898 was nearly complete when I visited the 

locality in 1914. 

If crustal change were the only factor concerned in the .modification of the marsh boundaries, it would be possible to indicate a number 

of crustal blocks underlying San Francisco 

Bay which are moving more or less independently, for the distribution of marsh advance 

and marsh retreat is somewhat systematic. 

South of Dum barton Point on the east coast and 

Ravenswood Slough on the west all recorded 

changes are of the nature of marsh retreat. 

Thence northward to J: ohnson Landing on the 

east coast and to Belmont Slough on the.west 

the records indicate marsh advance, and beyound those points they show retreat. This 

distribution suggests that under the second of 
HYDRAULIC-MINING . DEBRIS IN THE SIERRA NEVADA. 

these tracts crustal change is so slow that the 

silting up of the bay finds expression in marsh 

enlargement, while adjoining parts are sinking 

so rapidly as to prevent that expression. 

.A.:fter the earthquake of 1906 it was observed 

that certain structures in the southwestern part 

of the marsh drained by Ravenswood Slough 

bore a different relation to the levels of high 

tides, and the observer inferred·· t!J:at -the land 

had gone down several inches. · At the same 

time some cottonwood trees standing on firm 

ground at the edge of the marsh died, having 

l)resumably been killed by the admission of 

brine to their roots. The locality is within a 

tract of subsidence, as indicated by the retreat 

of the marsh front between 1858 and 1898. 

Though the evidence as to: changes "in prog7 

ress in the bay region is not so coherent as to be 

demonstrative, it still has cumulative weight. 

Considering together the. physiographic proof 

of general subsidence in very 'recent time, the 

evidence of dissimilarity in the geol~gic history 

on two sides of the Haywards fault, the testimony of the shell mounds to continued subsidence during aboriginal human occupation, 

the testimony of earthquakes and tidal observations to present unquietness, and the testimony of retreating marsh· fronts, I have little 

hesitation in concluding (1) that crustal 

changes are now in progress, (2) that they are 

somewhat unequal and diverse in their vertical 

elements, and (3) that their most general characteristic in relation· to sea leYel is subsidence. 

The basin of Suisun Bay is separated from 

the Great Valley of California by low hills, 

which constitute locally the eastern member 

of the Coast Ranges. North of Sacramento 

River they bear the name Montezuma. The 

passage through them is much wider than the 

straits farther west and is largely occupied 

by marsh lands of the confluent delta of 

Sacramento· and San Joaquin rivers. Valleys 

of small streams on both sides of the passage 

and also on the east side of the Montezuma 

:Hills are invaded by tidewater in such a way 

as to indicate recent subsidence. Features of 

the same character occur also on a gentle slope 

northeast of the l\1ontezuma Hills, but within 

short distances farther east and north such 

evidence of subsidence ceases to be available. 

The evidence . of extreme recency of subsidence· which is connected· with shell mounds 

does not extend so far eastward, the easternmost available locality being near the west 

end of Carquinez Strait. N. C. Nelson, after 

his work about the western area, on the results 

of which I have already drawn, undertook for 

the United States Geological Survey an 

archeologic study of the region of Suisun Bay 

and the delta marshes, with special reference 

to the question of subsidence. He found shell 

mounds about the western shore of Suisun Bay 

but not farther east, the distribution of the 

mounds apparently depending on that of the 

edible marine and brackish-water mollusks. 

On and near the delta marshes many sites of 

aboriginal occupation are mounds, natural or 

artificial, but in none of the places· examined is. 

the mode of occurrence of refuse deposits, etc., · 

such as to demonstrate subsidence during the 

epoch of human occupation. Aboriginal remains were indeed found below tide level but 

not in places where the possibility could be excluded that they had been lowered by the 

settling together of an underlying soft deposit. 

The 30-foot terrace is not known ·in the 

Great Valley. In the region of the Sacramento-San Joaquin delta the delta marshes 

occupy a belt along the west side of the valley. 

From their eastern edge an alluvial plain rises 

-to the base of the Sierra. The lower part of 

the plain slopes so gently t~at 8 miles is taken 

for the first 50 feet of ascent, and on this part 

the streams from the mountaills have no 

valleys. In its natural condition the plain 

grows by deposit from the streams. We may 

infer that had it been submerged at the time 

of the making of the 30-foot terraces the water 

level would have been marked upon it by 

deltas or other features of shore topography, 

but none have been reported. The slope has 

been accurately mapped with 5-foot contours, 

and a study of the map fails to discover any 

littoral features, but only those characteristic 

of alluvial fans. Although the results of map 

study are less satisfactory than ~hose of field 

examination, I regard the presence of a shore 

line equivalent to the 30-foot terraces as improbable. 

The sloping plain at Antioch, which ends 

northward in a bluff facing the broad strait, 

appears to descend eastward as well as northward and to pass beneath the marsh lands of 

the San Joaquin Delta. Near Antioch its 

surface is even, except for incised channels of 

drainage and a parapet of dunes along the 
SUBSIDENCE OF THE LAND. 23 

ri,"Ter.front, but eastward the suTface undulates. 

The sand of which the plain is composed has 

there been molded by winds, and the general 

·reln.tions of the plain are somewhat obscmed 

by the diversification of surface. It is probable, however, that the plain actually extends, 

without any abrupt break or flexme, well into 

the Great Valley, and that its continui~y may 

be interpreted as evidence that the recent 

elevation and .subsidence in the San PabloSuisun district a:ffected also in some degree an 

adjacent part of the Great Valley. 

The delta marshes of the San Joaquin and 

Sacramento lie within the range of the tides. 

They are divided by a plexus of winding 

channels into islands. In its natural condition each island was bordered by a raised rim, 

the "natural levees" of the surrounding channels. In part the rims were so low as to be 

regularly overtopped by high tides; in part 

they were submerged only during river floods. 

The rims are composed chiefly of river silt and 

sand. The interiors of the islands are made 

up of peat with small a.dmLxtmes of silt. 

Below the peat is a floor of "hardpan," and 

the slopes of this floor continue the alluvial 

slopes which border the delta region. Manson 

and Grunsky 1 give the depth of the peat "near 

the outfall of. the rivers" as 40 to 60 feet. 

Measm·ements collected by Mr. Nelson give a 

maximum depth of 50 feet in the strait north 

of Antioch. The general fact appears to be 

that thQ delta deposits, including the peat 

marshes and their .silt rims, rest on a preexistent surface with alluvial slopes, and that 

the outlet of the earlier drainage, like that of 

the present, was westward to the Suisun basin. 

In nll probability these slopes record for the 

Grent Valley an epoch in which the Sacranlento and San Joaquin waters flowed as a 

river. tlu·ough the Carquinez and Golden Gate 

gorges to the ocean, and the present bays did 

not exist. Since that epoch the delta region 

hn.s subsided through a vertical distance equal 

·to the maximum depth of the peat plus the 

fall of the ancient river between the passage 

at the Mon tezumn. Hills and its mouth. 

This subsidence is the latest recognized vertical movement of the land in the delta region. 

It mn.y have been slow and continuous. It 

Il\fo.nson, Marsdon, and Grunsky, C. E., Comm. Public ·works California Rcpt. for 1893-94, p. 26, 1895. Details are given by Manson in 

'roch. Soc. Pacific Coast 'l'rans., vol. 5, No.4, 1888. 

may have been interrupted by periods of rest 

or of elevn,tion. It may have been completed 

long ago or it may be still in progress. If it 

was completed long ago, it created a bay in the 

Great Valley, a fomth bay of the San Francisco 

chain, and wi.thin this bay the delta plain was 

afterward built. If it occmrod gradually and 

slowly and is still incomplete, the growth of the 

delta plain may have kept pace with it, preventing the formation of a bay. 

The hypothesis .of a bay, or inland sea, has 

been advanced with confidence by engineers 

who have studied the problems of flood control. 

According to Manson and Gruns~y, 2 " Suisnn 

Bay may be regarded as the remnant of the 

inland sea which at one time covered the interior valley and which more recently covered all 

those portions of this valley which are now 

embraced in the deltas of the two rivers." 

·Heuer, Handbmy, and I-Iarts, 3 speaking of the 

Great Valley, say: "From an examination of 

the geology of the surrounding country it seems 

probable tha.t Suisun Bay is all that is left of a 

large inland .sea, the leveling of the weather and 

rainfall having filled the remainder and converted it into land by the eroded material carried down by the rivers from the surrounding 

mountains." Foote 4 speaks of "the Great 

Valley of California, as nat me built it, by f!.lling 

an inland sea with debris from the hills." So 

far as I have gleaned from the reports of geologists, the latest known marine formations in 

the Great Valley are of middle Tertiary age and 

were deposited not long after the valley was 

created by the upraising of the Coast Ranges, 

but it is not probable that the inland sen, to 

which the quoted passages refer wn.s so ancient. 

A sea of which Suisun Bn.y is the remnant could 

not have existed before· the creation of the 

present bay system by post-Tertiary subsidence. 

Under the hypothesis of an inland sea subsidence preceded delta building and probably has 

now. ceased. Under the simplest alternative hypothesis subsidence was continuously accompanied by delta building and probably has not 

ceased. Evidence bearing on either hypothesis 

bears also on the question of present subsiden~e. 

2 Op. cit., p. 25. 

a Heuer, W. H., Handbury, T. H., and Harts, W. W., 59th Cong., 

1st sess., H. Doc. 262, pp. 4-5,1905. Also, in the same words, Biddle, 

John, Jackson, T. H., and Leeds, C. T.,62d Cong., 1st sess., H. Doc. 81, 

p. 6, 1911. 

c Foote, A. D., Am. Soc. Civil Eng. Proc., vol. 35, p. 830, 1909. 
24 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

Mention has already been made of drowned 

stream valleys northeast of the Montezuma 

Hills. The alluvial foreland of the hills 

descends below sea level in Yolo basin, one of 

the basins lateral to Sacramento River. Small 

streams from the hills crossing this foreland 

have carved valleys ill it, and the valleys 

descend below sea level. When these valleys 

were carved the foreland must have stood 

higher than now, and the preservation of the 

valleys shows that the time of their making was 

not- remote. This feature therefore indicates 

modern subsidence. The eastern face of the 

Montezuma Hills, having been pared away by 

Sacramento River, has no corresponding foreland. South of the strait the foreslope of tht. 

Diablo foothills has been so far remodeled by 

the wind that its evidence is. not altogether 

clear, but the fact that some of the Wind-made 

hills are now surrounded by marsh lands of the 

delta (see Pl. III, B) shows subsidence without 

indicating its date. The apparent continuity 

of the wind-modeled plain with the dissected 

plain at Antioch, where the condition of the 

dissecting channels indicates ·subsidence in 

progress, suggests without demonstrating ~ 

common history. 

If the delta was formed in a body of standing 

water its process of formation would presumably be that which is illustrated on the lower 

Delta of the Mississippi. The water would first 

be shoaled by subaqueous deposits of silt, then 

the channels would be outlined by the projection of pairs of flanking embankments, and 

then the shoal spaces between embankments 

would be occupied by vegetation and the 

formation of peat would begin. If the formation of the delta kept pace with subsidence the 

silt embankments and the peat beds would 

alike begin their growth on the foundation of 

old alluvium and. would be built up simultaneously. In one case the peat would overlap 

the silt deposit, thinning as it approached an 

embankment; in the other it would normally 

be about as deep near an embankment as in 

the middle of an island. The distribution of 

peat beds of different depths, so far as I know 

it, favors the second hypothesis; and so does 

the great n1aximum depth of 50 feet or more. 

The structure of the delta, being thus indicative of continuous slow subsidence up to a very 

recent date, is favorable to the hypothesis of 

subsidence now in progress. 

Another feature suggesting ·modern subsidence-:-the. one, in· fact, which first directed 

attention .to this subject-is the exceptional 

magnitude of the lateral basins of the Sacra- . 

mento Valley. All rivers traversing alluvial 

plains to which they are making additions 

build their banks higher than the .land beyond 

and thus make lateral basins, but I lmow of no 

other river system in which the upbuilding of 

the banks has so far outstripped that of the 

adjacent valley. Over an area of about 50 

square miles the floor of Sutter Basin lies below 

the low-water level of adjacent parts of Sacramento and Feather rivers, and nearly twice 

that area in Yolo Basin lies lower than the 

adjacent water of the Sacramento. As there 

evidently are several different ways in which 

such a condition may have originated, its existence does not demonstrate a history of development, but one of the possible origins is 

connected with subsidence. With· &low subsidence of the valley the rivers would tend to 

raise their banks gradually by deposition of 

silt as fast as they were lowered by subsidence, 

but the quantity of sediment brought to the 

lateral basins would not be correspondingly 

increased. 

The hypothesis of present subsidence in the 

middle and northern parts of the Great Valley 

finds its strongest support in the depth of the 

peat accumulated under the delta marshes. It 

is less surely supported by drowned stream 

valleys at the south end of Yolo Basin and by 

the imperfectly studied relations of sand dunes, 

and it accords well with the exceptional development of flood basins in the Sacramento 

Valley. 

If subsidence is accepted as the general character of crustal movement at the present time, 

alike in the bay region, the delta region, and 

the Sacramento Valley, it does not follow that 

the change has everywhere the same rate. 

Diversities such as have characterized the 

movements of the past in different areas may 

plausibly be ascribed to those of the present. 
CHAPTER IV.-CHANGES IN THE CONDITION OF RIVERS FROM ARTIFICIAL 

CAUSES. 

The changes in streams brought about by the 

activities of white men, practically dating from 

the discovery of gold in 1848, have arisen (1) 

from the overloading of the streams with 

detritus and (2) from the surrounding of parts 

of the inundated area by levees so as to restrict the freedom of the valley rivers to expand 

in time of flood. The overloading was caused 

chiefly by hydraulic mining. Agriculture and 

other industries which disturb the soil and expose it to wash by rain contributed to the 

effect, but their influence was relatively small. 

CHANGES DUE TO MINING. 

reduction of slope and of velocity. Consequently in each river -the capacity for transportation was reduced at this point, and part 

of the load of debris was arrested. The resulting ·deposit extended toward the valley 

from the foot of the range, and usually reached 

quite to the mid-valley trunk stream. It may 

conveniently be called a piedmc;mt depo.sit. 

Its. material was very coarse near the head and 

finer below. 

Continuous with the piedmont deposits were· 

deposits in Sacramento and Feather rivers, the 

trunk .s~reams of th~ Sacramento Valley. 

Their characteristic material was at first mud, 

Some of the hydraulic mines discharged their or "slickens," and afterward sand. 

tailings directly into · streams, others upon Each mining dump had a somewhat conical 

gentle slopes of the land, where the coarser form, its slopes radiating from a vertex. The 

material accumulated in fan-shaped heaps or deposits of the upland creeks made broad 

dumps. Usually the coarser material accumu- gravelly plains on which channels shifted with . 

lated also in the streams, forming local deposits every flood, and later they were .carved into 

which were gradually swept forward. Exam- terraces. The same description applies to the 

pies of mine dump and coarse stream deposit piedmont deposits, except that not all of them 

are shown in Plate V. have been ·excavated. to such an extent as to 

Initially, as the tailings issued from the develop terraces. The deposits of the trunk 

mining sluices, there was a division · of the . rivers are little wider than the original channel 

debris, the coarser part being swept along the beds. 

bed and constituting the bed load of the stream, With the building up .of stream beds the 

the finer being borne in the body of 'the current planes of high water were raised and the area 

and constituting the suspended load. The of inundation was increased. In the mountain 

partition of debris into bed load and suspended and piedmont districts this has been accomload continued throughout its journey, but the panied by a decreased flood depth, a change 

nature of the partition varied, because sluggish tending to reduce velocities and limit the ability 

currents could suspend only the finest clay, of the streams to transport debris. Along the 

whereas swift currents might suspend fine or trunk streams it has turned a larger share of 

coarse sand. the flood water into the lateral basins,·. thus 

Some of the creeks flowing through the up- reducing the discharge in the channels and 

lands that stand between river canyons ac- tending to reduce the ability of the streams to 

quired very heavy deposits, a:r;t.d there were transport. On each stream, however, the 

large accumulations also in the mountain tendency to reduce transportation was a tencanyons of some of the rivers. (See Pl. VI, B.) dency only, being opposed and overpowered 

After the checking of the n1ining operations by the influence of increased slope. 

these deposits were attacked by the streams, 

those of the upland. creeks being trenched and CHANGES DUE TO RECLAMATION. 

those of the river canyons largely removed. During the entire period of the invasion of 

Where the rivers leave the mountain gorges the Sacramento Valley by mining debris, the 

and enter the Great Valley there was an abrupt regimen of the rivers has been modified also 

25 
26 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

by the construction of levees. Tract after 

tract belonging to lateral basins or to the deltas 

has been surrounded by embankments so as to 

shut out the flood :waters, and eventually the 

entire area of natural inundation will be reclaimed in the interest of agriculture. Restricted in area, the: flood . waters have increased in depth, aild each great flood has risen 

higher .than· its predeces.so~. As '·the waters 

have been more and more confined to the 

channels the chanriel velodties have increased, 

and with them the ability to transport debris. 

If these changes had been independent of those 

wrought by mining debris they would have 

resulted in the automatic deepening and 

widening of the channels. -

Mining debris and reclamation by levees work 

together in 'producing high floods, and their 

flood effects can not be fully discriminated. 

They work in opposed ways on depth-of channel, the mining debris tending to build up the 

bed and reclamation to scour the channel 

deeper. 

TRANSPORTATION OF DEBRIS. 

may be· transported. The finer the debris the 

greater the capacity. Capacity is affected also 

by the shapes of the particles of debris. The· 

range of variation in respect to size is so much 

greater thai?- the range in respecttto density and 

shape that·_only the size factor is usually considered in relation to capacity. Size may be 

measured 'by diameter or by vohune. In 

whichever way it is measured, an incf'ease in 

fineness causes a somewhat greater increase:.in 

capacity. ··L 

Oapacity varies with the ratio of depth of.· 

water to width of stream. In the main, capac- ' 

ity increases with increase of the ratio (and this 

is true of the streams of Sacramento Valley), 

but the opposite rule applies to very small 

values of the ratio. . 

The fact that there is a lin1itiiig .. · condition 

below which transportation does not take place 

finds expression in the word competent. For a 

stream· of given discharge, flowing. in .a given 

channel and dealing with debris of a given fineness~ there is a competent slope; in a channel 

of given form and slope and with debris of 

given fineness there is a competent discharge; 

The series of changes thus outlined have been and for a given discharge in a given channel 

effected under the natural laws controlling the there is a competent fineness. 

work of streams. . Changes are still in progr:ess The ratio in which capacity is modified by a 

and their results may be forecast, provided th.e change in slope, discharge, fineness of debris·, 

stream laws are known. ·The fo.Uowing para- or depth of' current is greater when the condigraphs summar!.ie·such 6f the laws as are spe- tions are riear competence than when they are 

cially. involved.· in the moverp.ent of mining far above competence. · In other words, capacdebris~. :;tnd ·the· ~ssociated prcibl~ms. of flood ity is most sensitive to ·changes in the condicontrol. '.• . ·; · ..• ; .... , . ~ . ,. tions which control it when near its lower limit. ·;o, . . ,, , . 

The quantity Qf d~br.is\vh1c't} a ·given strean;t These laws have been experimentally detertransports is.its loaci'; tb.~ quantity'i't ca.n.trans- mined for the bed lo~d l· ·tr~ated by_jtself, and 

port may be called 1ts\~apac'lty. '; :rhe'load may they are believed: to ;be approXiinately true for 

b<:lles8 than the capa-city but n.ot ·greater: the_ stispen:ded load .by ·itself.~: Nevertheless 

Capacity varie~ with slqpe~ The greater the they can not· be. affum.e'd of the total load, beslope the greater· the·:·capacity; and the-change cause of cer~ain complications;growing out of 

in capacity is alw~ys)arger .~han the change· in the shifting of material from one load to the 

slope. · other. For most _of the purposes of this report 

Cap.!l-city varies with discharge. · When di~- their important application is to capacity for 

charge· is incr.~asedl· the .resulting increase in the transpor'tation of bed load. 

capacity is greater· 'than··~- the incr·e~se in dis- If a stream which is loaded to· its full Qapaci.ty 

charge; the' ~apacity ·_per: unit of discharge is reaches a point where the slope is less,' it beincreas~d. But·an increase in discharge· does comes o~~rl<?aded with reference to. the· gentler 

not enhance cap,~,toity 0 much as the· same ratio . slope and part of the load is droppe_d, .rn·aking a 

of increase in slqpe .. · . . · · . ' deposit:.: If· a fully loaded strea:QJ. ··reaches a 

Capacity ·va~les. 'irith '-the character of the point ·where the slope is steeper, its enlarged 

debris transported. ·The lower the specific capacity causes it to take more load, and the 

gravity of the debris the greater the capacity- taking of load erodes the bed. If the slope of 

that is, the greater the weight of load which 1 Sec U. S. Geol. Survey Prof. Paper 86, 1914. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE V 

A. A MINING DUMP ON THE SIDE OF A SMALL CREEK VALLEY. 

The mine (not shown) is at the right. The tailings, discharged from the mining sluice, have built a fan-shaped deposit, 

but this deposit contains only the coarser part of the tailings. At its lower edge the dlllDp is attacked by the creek, 

and some of it is washed away whenever the creek is in flood. Photographed in 1905. 

B. ONE OF THE LARGER CREEKS OF THE UPLAND, WITH ITS DEPOSIT OF MINING DEBRIS. 

At the right is a partly eroded mining dump. The photograph waa made in 1908, and at that time the mining dumps were furrnshing so much debris to the creek that the erosion of its deposit had scarcely begun. 

I 

MINING DEBRIS NEAR ITS SOURCE. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE VI 

A. A SIERRA CANYON BED IN ITS NATURAL CONDITION. 

The water channel occupies the entire width. 

B. A SIERRA CANYON CLOGGED BY MINING DEBRIS. 

The surface of the debris constitutes a broad :plain that is covered by water only when the stream is in flood. 

The low-water channels traverse this plam. The photograph was made in 1908. At that time most of 

the canyon deposits had been removed. (See Pl. VII, A.) This one is the head of a piedmont deposit. 

(See pp. 28, 52.) 

I 

CHANGE OF CONDITION CAUSED BY MINING DEBRIS. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE VII 

A. MIDDLE FORK OF YUBA RIVER NEAR NORTH SAN JUAN IN 1905. 

The canyon received a deposit of very coarse minin& debris, which was afterward eroded. The terrace here shown is a remnant of this deposit. The exposure of bearock at the left indicates that the river has nearly recovered its 

original profile. 

B. AN UPLAND CREEK NEAR NORTH SAN JUAN IN 1905. 

The debris deposit has not been trenched by the stream and may still be growing at this point. 

I 

MINING DEBRIS OF RIVER CANYONS AND UPLAND CREEKS 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE VIII 

"'!."--. 

A. AN UPLAND-CREEK DEPOSIT IN A REGION OF MANY MINING DUJ.\!PS. 

-: . ..... ~ 

... -~-.. · -: ')~ •; ' 

During the growth of the deposit a forest was overwhelmed, and its stumps and lo~s are now being disentombed. New vegetatwn takes possession of parts of the valley where erosion is least acttve and helps to restrain the erosive 

work. Photographed in 1905. 

B. A HEAVY CREEK DEPOSIT OF THE UPLAND, NOW SUFFERING EROSION. 

Photographed in 1905. 

I 

MINING-DEBRIS DEPOSITS OF UPLAND CREEKS. 
CHANGES IN THE CONDITION OF RIVERS FROM ARTIFICIAL CAUSES. 27 

a stream's bed is not adjusted to the stream's 

discharge and to the load it has to carry, then 

the stream continues to erode or deposit, or 

both, until an adjustlnent has been effected and 

.the slope is·just adequate for the work. 

Any changeof conditions which destroys the 

adjustment between slope, discharge, fineness, 

and load imposes on the stream the task of readjustment and thus initiates a system of changes 

which may extend to all parts of the strean1 

profile. The mining debris disturbed the adjustment of streams by adding to their load. 

Reclrunation by levees disturbs it by increasing 

the flood discharge in certain parts of the river 

channels. 

The 'law of adjusted profiles applies to 

streams with mobile beds-alluvial streams. 

Streams with fL~ed beds are normally underloaded, and their beds are modified only by 

abrasion. Th.is process works toward an adjustment of slopes but with exceeding slowness, 

and the factors involved are different from those 

of alluvial streams. 

The channel of an alluvial stream is composed of an alternation of deeps and shoals. 

'r.he din1ensions of these are related to the discharge. With variable discharge they are continually modified, each particular discharge 

tending to adjust them to its needs. Because 

of the greater power of streams during flood, 

the pattern of the bed is more nearly adjusted 

to flood conditions than to any other. 

An alluvial stream which is not confined by 

rigid banks ~hapes for itself a course made up 

of curves. The curves are not stationary but 

undergo continual changes. The curve pat~ 

tern is large for a large stream and small for a 

small one. In a variable stream the pattern 

is adjusted to the needs of the flood discharge. 

The general slope of a stream bed is deterJnined chiefly by the magnitude of the load 

that travels at time of the larger floods. 

1'he laws thus far stated apply to the transportation of debris along a bed composed of 

sin1ilar debris. When a stream ·is made to 

sweep debris along the unyielding bed of a 

. sluice or flume other laws apply. Capacity is 

greater for smooth beds than. for rough. It i~ 

greater for coarse debris (up to the limit of 

competence) thru1 for fine. It is in general 

greater for a flun1e than for a natur~l strean1 

of the same size. 

ACCUMULATIONS OF D£BRIS IN THE 

MOUNTAINS. 

The stream of ,,-ater by which tailings were 

delivered to a mining dump was artificially 

guided and usually ceased to flow after cessation of mining. If the dump lay wholly on a 

hillside it was afterward washed only by rain, 

and no important fraction of it was removed. 

:Many of the smaller dumps thus became essentially permanent deposits. The larger hillside 

dumps extended to waterways, and these were 

excavated by the streams on whose courses 

they encroached. Other dumps were built 

wholly in stream valleys and were subject to 

excavation fron1 their beginning. As a whole 

the dumps have yielded and are still yielding a 

large annual tribute to the streams. Their 

contribution will continue, with gradual diminution, for an indefinite period; but a portion 

of their store of debris may be regarded as 

permanently placed. 

Drifting forward from the dumps, during the 

mining and afterward, a large amount of debris 

gathered in the valleys of the upland creeks. 

This ·material is being fed to the rivers gradually and is perhaps at present the chief source 

of the rivers' supply of debris. (See Pl. VIII.) 

The excavation of such deposits leaves a 

terraced valley, and as the stream works down 

toward its original channel patches of terrace 

are here and there s ti·anded on the slope in 

such -positions as to be exempt from further 

attack. 

Some mines discharged their tailings directly into the canyons of rivers, and the mountain rivers have received also the outwash from 

dumps and creek valley deposits. Before the 

hydraulic mining the river beds were made up 

largely of bedrock and great boulders, with 

only a few reaches of coarse gravel. (See Pl. 

VI, A.) Their normal load of debris was less 

than their capacity. In the period of most 

active mining they received more debris than 

they could carry, and the overload was deposited. When mining was checked they 

again became underloaded and the new deposits were excavated. (See Pl. VII, A.) 

Little debris now remains in their beds, and 

the rivers· deliver promptly to the piedmont 

deposits all that they receive from the dumps 

and upland creek deposits. 
28 HYDRAULIC-MINING D:EBRIS IN THE SIERRA NEVADA. 

PIEDMONT DEPOSITS. 

The piedmont deposits began with the beginning of hydraulic mining and grew not only 

during the mining period but for years afterward. The coarse gravel of the canyon deposits was all caught. by them, and their 

growth probably continued until the canyons 

were emptied. They received ·also both gravel 

and sand from the upland creeks. Their building was accompanied by a sorting of the debris, 

the coarser portion lodging high on the slope 

and the finer farther do':Vfi. Their growth 

continued long after the culmination of the 

upland deposits but eventually ceased and was 

followed by excavation. In the piedmont 

deposit of American River the stream is well 

intrenched, and stages of its erosional work 

are recorded by terraces. Low terraces have 

appeared also along Bear River. On Yuba 

River the main channel has been deepened 

near the head of the deposit, and farther down 

the natural development of excavation has 

been modified by a dam. 

At Parks Bar Bridge, which crosses the Yuba 

where its bed begins to broaden outside the 

mountain canyon, the summit plain of the 

deposit was well recorded by a photograph in 

1905 (see Pl. IX, .A:), and in 1913 it was observed to retain the same height, but the 

depth of the channel dividing it had increased 

in the interval from 11 to 21 feet, showing a 

scour of 10 feet in the eight years. Three 

miles above, in the mouth of the canyon (see 

Pl. IX, B),· where the passage is too narrow 

for the development of terraces, is a gaging 

station .of the Geological Survey, and the 

changes in the channel bed are well shown by 

the records of low-water ·stages in successive 

autumns. The gage readings corresponding to 

a discharge of 500 cubic feet per second are as 

follows: 1 

Feet. 

1903.------------- - - - - 13. 6 

1904.----------------- 13. 5 

1905.------------- - - - - 11. 6 

1906.---------- .. ----- 9. 3 

1907- ------------- - - - - 8. 3 

1908- ------------.. - - - 7. 1 

Feet. 

1909 ... - . - - - - - - - -. - . . . 5. 0 

1910 .................. 4.8 

1911------------------ ~ 4 

1912 .... ---------- .... 4. 0 

1913 ...... ---- ........ 4. 0 

At Marysville, where the Yubt\ joins the 

Feather, the record of low-water stages for the 

same period (seep. 29) shows a total lowering 

of 2.9 feet. The sequence of levels is here less 

orderly than at the upper gaging station, partly 

because the low-water stages for different years 

correspond to different discharges and partly 

because the local conditions have been modified 

by engineering works for the control of the rivers, but the two records are of the same general 

tenor. The maximum phase of the piedmont 

deposit has been passed, and the work of excavation has begun. The maximum came earlier 

at the head of the deposit, having already been 

passed when the definite record began in 1903; 

at the river mouth it occurred between 1903 

and 1906. But for artificial interference with 

the work of the river the rate of scour at the 

head of the deposit would have been considerably greater and the scour at its foot less. 

Th.e excavation of the deposit is accompanied 

by further sorting of the debris. That which 

is swept out at Parks Bar Bridge consists of 

coarse and fine gravel, with a generou~ filling of 

coarse sand, but that which reaches the mouth 

of the .river at Marysville consists of fine and 

coarse sand, with a small amount of fine gravel. 

The coarse gravel is arrested on the way, 2 

doubtless in company with other gravel brought 

from the upper river, while part of the sand 

whi~h had been incorporated with the gravel at 

the head of the deposit joins with the finer 

debris in transit from above. It if? not to be 

assumed that the coarse debris is permanently 

arrested, but only that its forwarding is delayed until the upper river shall cease to send 

.down a heavy lo.ad of sand. On the exhaustion 

of the mining debris stored above, the transportation of the coarse debris of the piedmont 

deposit will become more active, and gravel 

will largely replace the sand in the lower Yuba 

and lower Feather. A return t9ward the normal profile will tend to restore the "gravelly 

ford" of the Yuba by which travel is said to 

have approached Marysville in early days. 

The piedmont deposits of Yuba and Bear 

rivers extend to their mouths in Feather River 

and are there continuous with deposits in the 

Feather. · That of American River is continuous with a deposit in Sacramento River. 

These readings not only confirm the record 

at Parks Bar Bridge, by indicating a total 

scour of 9.6 feet in 10 years, but show that the 

deepening of the channel has been progressive. 2 These statements as to the movements of gravel at the mouth of 

Yuba River were written several years ago and were then accurate. 

l Based mainly on data published in U. S. Geol. Survey Water-Supply The present condition is described in the closing paragraphs of this chapPaper 298, pp. 254-255, 1912. ter. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE IX 

A. TREES ON THE LEFT BANK OF THE RIVER PARTLY BURIED BY MINING DEBRIS. 

rhotographed June 6, 1905. In July, 1913, the locality Wlll3 revisited, photograph in hand, and the height of the deposit 

found to be unchanged. 

B. THE "NARROWS " OF YUBA RIVER IN 1905. 

The Geological Survey's gaging station is at this point. A short distance above it the deposit was sounded in 1899 

and found to have a depth of 85 feet. 

CULMI ATION OF THE YUBA RIVER PIEDMO T DEPOSIT AT PARKS BAR BRIDGE. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE X 

A. MANZANITA MINE, NEAR SWEETLAND. 

Beyond the buildin&s is a ridge bearin$ trees on its crest. The camera stood on a similar ridge. The outer slopes 

of the ridges ana the tabular top ot the intervenin" hill are parts of the original surface before the mining. In 

the survey to measure the quant1ty of earth removed they helped to indicate tne ori~inal configuration of the land. 

The greatest depth of excavation within the field of view was 180 feet, and the vomme of the visible part of the 

openmg is about 13,000,000 cubic yards. The estimated volume of the entire excavation at this point, including 

the Manzanita and American mines, is 47,900,000 cubic yards. 

B. NORTH WALL OF THE WEST ARM OF THE NORTH BLOOMFIELD MINE. 

The height of the wall is 250 feet. The photograph was made in 1908, about 20 years after the last mining in this part 

of the opening. Storm waters have continued the work of excavation, sculpturing the cliff into alcov2s and 

buttresses. Part of the excavated earth has lodged in a lower part of the mine and part has escaped to a neighboring creek. On the cliff the surface wash haa been so active that ve~etation has found no foothold, but elsewhere 

the work of reforestation has begun. The trees in the foreground all stand within the mine. 

HYDRAULIC PLACER MINES. 
CHANGES IN THE CONDITI0N OF RIVERS FROM ARTIFICIAL CAUSES. 29 

Other piedmont deposits clog only the streams 

from which they originate. The largest is that 

of the Feather, which has a visible length of 

about 30 miles and then passes under a. slackwater pool occasioned by the deposit from the 

Yuba, which acts as a dam. 

DEPOSITS IN THE VALLEY RIVERS. 

The debris delivered by the piedmont streams 

to the trunk rivers of the valley imposed a load 

which those rivers could not transport without 

increase of slope, and the necessary increase 

was made by depositing part of the load on the 

channel beds and building them up._ The depth 

of the deposit was thus related to the m.agnitude of the load transported on its slope. The 

deposit grew through the period of active mining and afterward until the piedmont deposits 

had passed their maximum, and then it .began 

to decline. The depth of the deposit was also 

affected by the quantity of water flowing 

through the channel in time. of flood, a quantity which tended to increase as access to 

lateral basins was restricted by levees. 

The history of change is most definitely 

known through records of low-water level at 

Mf!,rysville and Sacramento, the variations of 

lowest water surface from autumn to autumn 

cmTesponding approximately to v~riations of 

the general level of the channel bed. At Marysville ·the observations were made on a gage 

established in Yuba River about 0.7 mile from 

its junction with the Feather, and a daily series 

has been kept since 1893 under the direction of 

the levee commissioners of the city, -to whom 

I am indebted for data contained in Table 2. 

The gage was established in 1873, and the low~ 

water record is continuous from 1883. For 

years earlier than 1873 there are no exact data, 

.but estimates of different observers indicate an 

original low-water level at least 10 feet below 

that of 1873. 

At Sacramento gagings of Sacramento River 

were made, and continuous readings have been 

reported_ by the United States Weather Bureau 

· since 1896.1 For certain earlier years records 

of low-water are reported or cited by Mendell 2 

and by Rose.3 In the original cond~tion of the 

river there was a tide at Sacramento with a 

range of about 3 feet. In 1871, when the low-

' Dally river stages at river gage stations on tho principal rivers of tho 

United States, 1896-1910, pts. 6-10, U. S. Weather Bur. 

2 Mendell, G. H., Chief Eng. U.S. Army Ann.·Ropt. for 1882, p. 2507. 

a Rose, A. H., California Comm. Pub. Works Ropt. for 1894, p. 33. 

stage level had been raised 4 or 5 feet, there was 

still a tide of 9 inches/ and Hall records 2 

inches in 1879.5 Rose also gives the,range for 

years earlier than 1860 as" about 2 feet." The 

United States Coast and Geodetic Survey tide 

tables give 1.5 feet as the mean range and 3.2 

feet as the great tropic range, the figures being 

based on observations made in 1857. As the 

bed continued to rise the tide disappeared, but 

it was again observable when the bed was .afterward reduced. In 1913 the range was reported as 1.5 feet. The freedom of tide transmission from Suisun Bay to Sacramento is re~ 

lated to depth of water in the lower river, and 

the periods of larger tide at Sacramento are 

also periods of greater depth of water. Dw·ing 

such periods the deposits in the channel were 

relatively shallow, and because of these correlations the range of variation of the annual lowstage levels is less than the range of variation in 

the depth of the river deposit. The raising of 

the low-stage plane from the vicinity of mean 

tide level to a position 13 feet higher was associated with more than 13 feet of deposit in the 

channel. 

TABLE 2.-Low-water records of Yuba River at Marysville 

and of Sacramento Rtver at Sacramento. 

[Feet above moan sea level.] 

Year. I Marysville. Sacramento. 

1849. . . . . . . . . . . . . . . . . . . . . . . . . [36. 8] o· 

1856......................... . . . . . . . . . . . . 0 

1869......................... . . . . . . . . . . . . 2. 9 

1873......................... 46.8 ........... . 1874......................... 47.8 

1875. · ................................... . 1876 .................................... . 1877 .................................... . 1878 .................................... •' 

1879 .................................... . 1880. ........................ 52.8 

1881 .................................... . 1883......................... '52. 0 

1884......................... 52.8 

1885............... .... .. .. . .. 51.1 

1886. ........................ 52.6 

1887. ........................ 51.3 

1888. ........................ 52.0 

1889. ........ .... ............ 52.3 

1890......................... 52.4 

1891......................... 52.7 

1892......................... 53.6 

1893......................... 53.0 

1894......................... 53.0 

1895... ...................... 53.0 

1896......................... 53.4 

1897. ........................ 54.5 

1898. ........................ 54.0 

1899. ........................ 53.8 

1900......................... 54.1 

1901......................... 54. 5 

4 Rose, A. H., op. cit., p. 33. 

5 Hall, W. H., California State Eng. Rept. for 1880, p. 68. 

4.9 

4.5 

7.1 

5.3 

5.5 

5.8 

7.4 

6.5 

10.5 

7.5 

10.0 

10.8 

9.6 

9.9 

7.6 

7.2 
30 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

TABLE 2.-Low-water records of Yuba River at Marysville 

and of Sacramento River at Sacramento-Continued. 

Year. 

1902 ........................ . 1903 ......................... . 1904 ........................ . 1905 ........................ . 1906 ........................ . 1907 ........................ . 1908 ........................ . 1909 ........................ . 1910 ........................ . 1911 ........................ . 1912 ........................ . 1913 ........................ . 

Marysville. Sacramento. 

55.0 

55. 3' 

55.8 

55.9 

55. 7 

55.3 

55. 1 

53.0 

52. 5 

52.9 

52. 2 . 52.4 

6.9 

7.0 

8.2 

6.3 

6.8 

7.3 

5.3 

5.5 

5. 1 

5. 5 

4. 1 

3.0 

Table 2 contains the low-stage gage readings 

at Marysville and Sacramento, together with 

water-level records of less precision for earlier 

years; and the same data are plotted in figure 

4. The zero of the Marysville gage was placed 

I 

n 

60~-------------------------------

/++ ........... \ 

•--.y"'"+•··/•+• •••• 

~ 50+-------------~~---r----+----+­

~ 

FIGURE 4.-Fluctuations oflow-water level due mainly to tho deposition 

of mining debris on river beds and its subsequent erosion. I, Yuba 

River in narrows near Smartsville; II, Yuba River at Marysville; 

III, Sacramento River at Sacramento. 

at the low-water level of 1873. At Sacramento 

there were two gages. The zero of one is· reported to correspond to the low water of 1856, 

and the readings from the other, as tabulated, 

are reduced to the same zero. A certain 

amom1t of ambiguity is occasioned by the 

tides, but it is probable that the lower low-water 

records at Sacramento all represent the combination of low tide with the autumnal low-river 

stage; and the graphic record has been adjusted m1der this assumption. 

The irregularities of the plotted curves· are 

connected largely with inequalities of maximum and minimum discharges from year to 

year. Exceptional flood discharges leave exceptional configurations of channel bed, which 

affect local details of low-water plane, and the 

low-water plane also varies in position with the 

magnitude of the low-stage discharge. Minor 

details of the curves may therefore be ignored 

in reading from them the general history of the 

building up and paring down of the channel 

deposits. 

The bed of Feather River at Marysville was 

built up rapidly during the period of increasing 

output of debris from the hydraulic mines of 

the Yuba River basin. · It continued to be upbuilt, but more slowly, after the checking of 

mining and during the chief excavation of the 

debris banks in the mountains, and accretion 

was not exchanged for reduction m1til five or 

six years after the excavation of the head of the 

Yuba piedmont deposit had begun. The downstream movement of the great body of debris is 

thus analogous to the downstream movement 

of a great body of storm water, the apex of the 

flood traveling in the direction of the current. 

The apex of the debris flood, leaving the mines 

in 1883, passed the mouth of the mountain 

canyon in about the year 1900 and the mouth 

of Yuba River in about 1905. 

The stream of debris from the Yuba is joined 

in the Feather by a smaller stream from the 

Bear and in the Sacramento by a stream from 

tho American. Water levels at the Sacramento 

gaging station are affected by all these strean1s. 

The debris wave from the Yuba may be assumed to be flattened and greatly extended 

during its long journey from Marysville, so 

that its influence on the water plane at Sacramento is gradual and of moderate amount. Its 

apex has perhaps not yet arrived, and if it has 

arrived it can not be discriminated in the composite effect. The wave from the American, 

having a much shorter course, reached the station while less expanded and has been the dominant factor in the determination of the lowwater curve. Its apex seems to have passed in . 

about tho year 1896; and the reduction of the 

river deposit began here a decade earlier than 

at the mouth of the Yuba. 

So far as the flow of debris from the hydraulic 

mining of the past is concerned, tho future history of tho channel deposits will be one of con-
CHANGES IN THE. CONDITION OF RIVERS FROM ARTIFICIAL CAUSES. 31 

tinual diminution, a progress toward the restoration of the river conditions of. the early 

fifties. That progress might be arrested by the 

resun1ption of hydraulic mining. It will be 

pr01noted by the reclamation of tho lands now 

subject to overflow. The confinement of flood 

waters of the Sae1·amen to and Feather to the 

channels of those streams would greatly increase 

their capacity for transporting debris and would 

eventually reduce the channel beds to lower 

levels than have been known. The partial confinement contemplated in the engineering plans 

for flood control will probably obliterate the 

effect of the invasion by mining debris. -

The deposit built in the Feather River channel by debris from the Yuba has the effect of a 

dam, causing slack water in the Feather just 

above. The pool had at one time a length of 

10 miles or more, being limited upstream by 

the piedmont deposit of the Feather. Afterward it was diminished by the encroacbmen t 

of that deposit and in recent years by the lowering of the low-water plane at Marysville. Its 

length in 19i3 was said to be about 6 miles. 

There is a similar ponding of Sacramento River 

by debris brought to its channel. by Feather 

River. 

'fhe piedmont deposits in the basin ·of San 

Joaquin ~iver are reported to be of moderate 

extent, and so little mining debris has reached 

the trunk stream that the river has remained 

tidal and navigable. 

As already stated, the flood of mining debris 

is analogous to a flood of 'Y'ater in its mode of 

progression through a river channel. It travels 

in a wave, and the wave grows longer and flatter as it goes. Where the channel is too small 

to contain it, the water wave spreads out over 

adjacent lands, and the volume thus escaping 

from the channel is tern poraril y stored, so as 

to regulate the flow at points below. The 

debris wave differs from the water wave in the 

fact that part of its overflow volume is permanently lodged outside the river channel, and 

in the additional fact that the material of the 

wave is not homogeneous. From the start 

there is a sorting of the debris, and the finer 

parts travel faster than the coarser, except that 

71139°-17-3 

some of the finer material is held in the interstices of the coarser. The visible part of the 

wave, that which at any time is exposed to 

the action of the current, exhibits a gradation 

from fine at the front to coarse at the rear. 

The debris in transit at any point is first siltthe ''slick ens'' of the miners-and then in 

succession sand, fine gravel, coarse gravel. At 

the mouth of Yuba River all these phases have 

been observed, the sequence b.eing automatic 

or normal as far as fine gravel. The appearance of coarse g1·avel, recently observed, has 

been hastened by engineering works that have 

narrowed, and thereby strengthened, the flood 

current a few miles upstream. In the lower 

Sacramento silt has been succeeded by fine 

sand and coarser sand. 

The prog1·ess of such a wave and its manifestation in the texture of bed material are 

complicated by two other factors-progressive 

comminution of debris and variation of flood 

discharge. The debris in .transit is continually g1·ound upon itself, and its particles are 

worn to smaller size, so that the coarser debris 

characteristic of the upper reaches of a stren.m 

does not appear in the lower reaches, and the 

load of fine debris is g1·eater. 

A great flood, as compared to a small flood, 

is able to carry coarser debris, or to carry more 

debris, or to do its work on· a gentler slope. 

Which of these phases of its com·parative activity shall be manifested in a particular division of the stream's course will depend on the 

character and quantity of the load brought 

from above. It may reduce the slope of its 

channel by scouring and leave behind a lowlevel channel bed of coarser debris, and in that 

event the minor floods of succeeding years will 

tend to steepen the slope by depositing debris, 

and the deposited debris will be finer than that 

on which it rests. As the closing work of each 

flood is performed by a discharge less than its 

maximum, it often happens, especially in the 

lower part of a river's course, that the coarsest 

part of a flood's load is so buried by fine material as not to be visible when the bed is exposed 

at low stage. 
CHAPTER V.-CHANGES IN THE CONDITION OF BAYS. 

The streams that discharge to the chain of presumably yielded their maximum quantit:y of 

bays (Suisun, San Pablo, and San Francisco) waste. The interval between surveys of ·san 

deliver along with the water a quantity of fine Pablo and San Francisco bays, averaging for all 

detritus, consisting of mud and sand. Lodging parts about 41 years, covered the .same time 

on the bottom the detritus tends to shoal the as the Suisun Bay interval, with the addition of 

bays, and combining with vegetation along the an earlier decade during which hydraulic 

margins it ~nds to contract them. These ten- mining was advancing toward its maximum 

dencies are opposed by the siow subsidence ·and a later decade during which the flow of 

of the land, and in the natural condition of the mining debris was slowly diminishing. 

region there may have been an approximate Suisun Bay is relatively deep in the southern 

.balance between the opposed factors. If such and middle parts, where it is traversed by a 

a balance existed, it has been overthrown by the group of channels from the river mouths to 

activities of the white man, which have so Carquinez Strait. Among the channels are 

increased the detrital loads of the streams islands and a broad, irregular shoal, to part of 

that the bays are now losing in depth and area. which the name Middle Ground is given. At 

The water of Sacr.amento and San Joaquin the north are two arms, broad and shallow, 

rivers reaches first Suisun Bay, then San Pablo known as Grizzly Bay and Honker Bay. In 

and San Francisco bays, and then escapes the period of 20 years the shoals, having a total 

through the Qolden Gate to the ocean. The area of about 30 ·square miles, received an 

forward movement is not continuous but is average deposit of 1.63 feet," the quantity of 

reversed twice a day by the tides, with the sediment being 51,000,000 cubic yards. The 

result that many eddies are formed and the depth of fill was greatest in Honker Bay 

river water is gradually mingled with: ocean (2.17 feet) and least on the Middle Ground 

water. The ;river water is also carried to all (1.25 feet). The channels are so irregular in 

the remoter reaches of the bays. The sediment form that it is not practicable to compute their 

is widely spread "\vithin the bays, mingling changes with close approximation by means of 

with smaller quotas from minor streams. It is the published soundings, but the general nature 

evident also that a part of it reaches the ocean, of their modifications is quite clear. Almost 

for in times of flood, while the rivers are turbid without exception they became narrower and 

and opaque, the outgoing tide through the deeper; almost without exception, also, the 

Golden Gate shows a tinge of yellow. quantity of material added at the sides was 

Some information as to the extent and dis- notably greater than the quantity scoured out 

tribution of the recent deposits is afforded by between, so that a net fill resulted. A rough 

the charts of the United States Coast and estimate places the net fill of channels at 

Geodetic Survey, which give soundings in all 13,000,000 cubic yards, and makes the total 

parts of the bays and at different dates. Com- deposit in the bay 64,000,000 cubic yards. 

plete surveys of Suisun Bay were made in In Carquinez Strait, which connects Suisun 

1867-68 and in 1887-88. A complete survey and San Pablo bays, the bottom is irregular. 

of San Pablo Bay was made in 1856, a small The depth changes ·so greatly within short dispart was resurveyed in 1887, and the re- tances that the magnitude of each recorded 

mainder was resurveyed in 1896. The north- sounding may be assumed to depend in part 

ern part of San Francisco Bay waR surveyed in on an accident of location, and computations 

1855 and again in 1895-1901; its southern part of average depth are subject to considerable 

in 1857-58 and in 1895-1899. uncertainty. Moreover, the surveys on which 

The interval of 20 years between the two the earliest and latest maps are based were 

surveys of Suisun Bay included 16 years of the made at uneven dates, so that the intervals 

most active hydraulic mining, together with between dates contrasted in different parts of 

the 4 years immediately following,· when the the maps range from 20 to 41 years. A com:.. 

temporary deposits of debris in the mountains parison was made by dividing the area into 14 . 

32 
CHANGES I~ THE CONDITION OF BAYS •. 33 

parts and studying each part separately, and 

it was found that the depth had apparently 

increased in 3 divisions and diminished in 11. 

T.he average apparent loss of depth in the 

11 divisions was much greater than the average gain in the other 6. From the data thus 

obtained it was estimated that the total amount 

of material deposited in the strait from the 

beginning of hydraulic mining to the year 1890 

was 40,000,000 cubic yards~ 

San Pablo Bay is traversed, from Carquinez 

Strait to the constriction separating it from 

San Francisco Bay, by a broad channel of simple contour. North of this is a great shoal occupying more than half the total area, and 

south of it are minor· shoals. In the 41 years 

between surveys the channel was much reduced 

in width and was also reduced in depth. The 

filling along the middle line was small compared to the marginal filling. The great 

northern shoal received a large deposit, and the 

eastern division of the southern shoal an important though small deposit; but the western 

division of the southern shoal suffered a loss. 

To give quantitative expression to some of 

these facts ·the computations were made by 

divisions, the channel being arbitrarily limited 

by the position of the 3-fathom contour in 

1856, and the northern shoal being separated 

into two parts, distinguished by different dates 

of resurvey. The data are exhibited in Table 

3. It is worthy of note also that the eastern 

part of the northern shoal received a much 

heavier depo~it than the western part. 

'l'AJH,1~ 3.-Data on sedimentanJ deposits in San Pablo Bay 

between the 8'/.lrvey of 1856 and later survmJS. 

Volume 

Area Depth of dePu.rt of bay. Period (squu.re of de- posit 

(yeu.rs). posit (million m1les). (feet). cubic 

yards). 

Channel. ............ 42 29.4 4. 86 147. 2 

North part of north 

shoal. ............. 31 8. 4 2. 11 18.3 

M:~·~af.~~t .. ~~ . ~~~~~~. 41 60. 9 2. 97 186. 3 

Southeast shoal ...... 42 7.3 2. 84 21.4 

Southwest shoa.l ..... 42 7.2 -1.25 - 9. 3 

Means and totala ......... 41 113. 2 a 3.13 (£ 366.0 

a ~l'ho moo.n dopth o.n<l total volume or tho deposits are adjusted to tho moan porlo<l or 41 years. 

San Francisco Bay is divided by a moderate 

coJ;~,striction at Goat Island into a northern 

third and a southern two-thirds. The north- · 

ern division is'· traversed by the Sierra waters 

on their way to the sea. The southern receives 

drainage from valley plains and coastal hills. 

The deposits in the southern division must be 

derived chiefly from soil waste, but they may 

include also a small tribu.te of mining debris, 

for the tidal currents tend to mingle the waters 

of the two divisions, and the strong day winds 

of summer promote the mingling by driving the 

surface waters southward. 

Table 4 contains estimates of the mean 

depth of deposits not only for the entire bay 

but for certain subdivisions. It fails to include, however, any estimate for Raccoon 

Strait or for deep-water tracts south and west 

·of Angel Island. In those regions the bed is 

so uneven that soundings made at different 

dates and at slightly different places are not 

comparable. The omission is thought to be 

unimportant, because the currents there are 

so strong that the formation of deposits is not 

probable. 

'l'ABLE 4.-Data on sedimentary deposits in San Francisco 

Bay between the survey of 1855-1858 and the sun:ey of 

1895-1901. 

Volume 

Area Depth of of dePeriod posit Part of bay. (years). (square deposit (million mtles). (feet)-. cubic 

yards). 

Channels: 

North of Goat Island .......... 43 ~6 2. 7 100 

Goat Island to 

San Bruno 

Point .......... 41 36 -1.8 - 67 

San Bruno Point 

to Dumbarton 

Point .. ~ ...... 40 15 1.9 29 

Shoals: 

North of Goat 

Island ........ : 43 37 1.0 38 

Goat Island to 

San Bruno 

Point .......... 41 53 . 5 27 

South of San 

Bruno Point ... 40 95 .7 69 

Means and to2721 tals ......... 41 . 70 196 

In two of the tracts separately recorded in the 

tables 'there is indication of negative deposi-
34 HYDE;AULIC-MINING -DEBRIS IN THE SIERRA NEVADA. 

tion-that is, the charts show for those tracts dertaken with reference to encroachments Oil 

increase of depth of water instead of decrease. the tidal prism (see pp. 86-88), revealed discrepOne tract is a shoal in San Pablo Bay lying ancies which may be significant. In localities 

south of the channel and east of Pinole Point; where a tidal marsh adjoins a shoal of gentle 

the other is the deeper water south of Goat slope one would expect the high-water line (repIsland. For each tract the mean increase in resented by the marsh margin) and the lowdepth is more than 1 foot. There are at least water line· to advance or recede together, 

three possible modes of explaining these excep- whether their positions are modified by depotional indications-by local scouring of the sition, by scour, or by subsidence. There are 

bottom, by local subsidence, and by errors in three such localities near the junction of San 

the charting. As to the first-mentioned possi- Pablo and San Francisco bays, one just east of 

bility, the shifting of deposits on the beds of San Pablo Point, the second north of San Quenchannels is a common occurrence, but the tin Point, and the third south of San Quentin 

scouring of muddy shoals is less common. Point. In each locality the recorded change in 

Usually such a shoal presents at its surface a the high.:.water line between 1855-56 and 1899-

layer of soft mud resting on firm tenacious 1901 has been slight, but the recorded change in 

clay, the one being easily disturbed and the the low-water line has been great. If it is 

other opposing a strong resistance to current assumed that the actual change in the position 

action. Ordinarily the mobile layer is thin, of the low-water line was small, and that the 

and for this reason the scouring of a foot or line is correctly placed on the later charts, its 

more from the general surface of one of the position as given on the earlier charts is on the 

lateral shoals is improbable. average nearly half a mile too far out. This is 

The evidence adduced in Chapter II leads such a discrepancy as would be occasioned if 

to the belief that the general region is affected the "plane of ·reference" for the earlier soundby slow subsidence and that some changes are ings were 1.5 to 2.0 feet lower than the plane of 

more or less localized. The two tracts under reference for the later soundings. Planes of 

consideration both lie in the district west of reference are determined by the discussion of 

the Haywards fault, where prehistoric subsi- tidal observations, but the· records discovered 

dence has been most pronounced. The hy- fail to show what observations were used for 

pothesis of present subsidence is therefore the reduction of soundings in these localities 

worthy of consideration, but neither of the two in 1855 and 1856. Negative evidence indilocalities affords corroborative evidence. If cates that the plane of reference and tidal corsubsidence had occurred in the tract· between rections in 1855 were based on tidal observaPinole Point and San Pablo Point the level of tions at Fort Point, and the Fort Point plane 

the adjacent marsh would have been lowered of reference used in 1855 was 1.0 foot too 

and its margin would have retreated landward; low. In computing the averages assembled i.n 

but instead of that its margin was somewhat Table 4 I have applied a correction for this 

advanced so as to encroach on the open water ·recognized error. 

of San Pablo Bay. If subf?idence had affected Because the Coast and Geodetic Survey 

the channel between Goat Island and San 1 charts are prepared for the use of navigators, 

Bruno Point it presumably would have affected and because an overestimate of depth involves 

also the adjacent shoals, but the shoals were danger to vessels, the general principle is recogfound to stand higher at the time of the second nized that such errors as affect the charted 

survey. soundings should be on the side of safety. 

As to the possibility that the exceptional The application of this principle has affected 

indications arise from errors of survey it is safe observations of depth and their reduction and 

to say that the later survey is not at fault also the selection of "characteristic" soundIts methods, which are fully recorded in the ings for the charts and has been embodied in 

archives of the Coast and Geodetic Survey, rules for the rejection of fractions, etc. The 

were thorough and adequate. The records of result is, first, that the charted depths are on 

the earlier work are less complete and leave the average less than the actual depths and, 

doubt as to some matters of method. A com- second, that the average difference between 

parative study of earlier and later charts, un- the charted and actual depths is greater for 
CHANGES IN THE CONDITION OF BAYS. 35 

rough surveying than for refined surveying. of the banks or shoals that border it. The 

As the earlier work was relatively rough and deposits involved in that extension have in 

the later was refined, the charted depths are some places a recorded depth of 8 feet and 

likely to be less on the old charts than on the over considerable areas a recorded depth of ~ 

new in localities where the actual depth was feet; and these quantities are much too large 

unchanged. to be charged to errors of survey. 

In view of these considerations I think it Other corroboration is found when the estiprobable that the indication of increased depth ,mates for the three bays are compared. Limon the shoal west of Pinole Point is due to error iting attention to the .deposits on shoals, and 

connected with planes of reference and possible expanding the Suisun estimate, which is based 

that the apparent increase of depth south of on surveys only 20 years apart, so as to make 

Goat Island is due also to some difference in it properly comparable with the San Pablo and 

method between earlier and later surveyS'. If San Francisco estimates, I obtain: 

this opinion is correct it follows that other reEstimates of ave:rage deposition on shoals in a pe:riod of suits -based on surveys of the same dates are 41 years. questionable and that generalizations from 

them must be regarded as of low precision. 

This qualification applies to the results for the 

northern half of San Francisco Bay, where the 

earlier soundings were made in 1855, and to the 

results for the whole of San Pablo Bay, where 

the earlier surveys were made in the first half 

of the year 1856. For these dates there is no 

record of tide stations in close association 

with the :field work, but there was a permanent 

station at Fort Point. The southern part of 

San Francisco Bay was surveyed in 1857-58, 

and in connection with that work the·tide observations at Fort Point were supplemented by 

observations at local stations. The first comprehensive survey of Suisun Bay was made 10 

years later and had the advantage of progress 

in the development of methods. Not only 

were there local tide stations, but provision for 

the stability of 'the plane of reference was made 

by connecting smne of the tide gages with 

bench marks. So far as I am able to judge, 

the esti1nates of deposition in Suisun Bay are 

well founded, and the estimates for the southern 

part of San Francisco Bay rank next in credibility. . 

No attempt is made to improve the estimates 

by applying corrections for the inferred inaccuracy of the plane of reference; the general 

avern.ges may have been affected by. compensatory inaccuracies in the planes used for other 

trn.cts. On the other hand, the least trusted 

estimates of average deposition are not discarded, because there is independent evidence 

accordant with their general tenor. · 

A corroborative fact is found in the contraction of the channel through San Pablo Bay, 

which has been brought about by the extension 

·Feet. 

Suisun Bay.................. . . . . . . . . . . . 3. 3 

San Pablo Bay. . .. .. . . . . . . .. .. .... .. .. .. 2. 5 

San Francisco Bay. . . . . . . . . . . . . . . . . . . . . . 7 

The general aspect of this sequence, which 

places the heaviest deposit in the bay that is 

nearest the ·river mouths and . the lightest in 

the bay that is most remote, is such as might 

have been anticipated, but my first impression 

in making the comparison was that a greater 

difference should be expected between the first · 

and second terms and a less difference between 

the second and third. There is, however, a 

modifying condition of which account should 

be taken. The material deposited on the shoals 

is fine mud that is brought by the rivers in 

suspension. Deposition is determined in part 

by the slackening of current as the muddy 

water enters a bay and in part by flocculation 

as it is mingled with salt water. Deposition 

from slackening would be much heavier in the 

first settling reservoir than in the· second, but 

deposition from flocculation would begin wherever the salt water was met. At low stages of 

the rivers the principal meeting occurs in Suisun Bay, but at low stages there is little mud 

in suspension. In tlm.es of great flood, when 

the largest load of mud is brought down, the 

river current dominates over tidal currents in 

Suisun Bay, and the principal meeting with 

brine takes place in the larger water body 

beyond Carquinez Strait. (See Chapter IX.) 

When account is taken of this factor there 

appears no improbability in the. relative magnitudes· of the estimates of deposition. for Suisun 

and San Pablo bays. 

If the figures are taken at their face value 

it appears ~hat heavy deposits have been made 
36 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

in Suisun and San Pablo bays and the connecting strait, and a moderate deposit in $an 

Francisco Bay. These deposits have been 

caused primarily by the surcharging of the 

valley rivers by mining debris and the detritus 

contributed by other. industries, and secondarily by the outwash ·of soil waste from the 

country immediately surrounding the bays. 

As the periods covered by the comparison of 

charts do not in any case represent the entire 

period of augmented detrital. load, considerable allowances are necessary in order to pass 

from the measured volume of deposit to the 

total volume accrued since tlie beginning of 

L-suisun Bay___l L--Carquinez Strait____l San Pablo Bay----:-' L-----San Francisco !Jay_____! 

FIGURE 5.-Graphic statement of factors controlling estimation of deposition in bays and strait for periods not covered by measurements. 

The periods covered by measurement are indicated for the· several 

units. A, Output of mining debris; B, soil waste; C, percentage of 

fine debris not deposited on inundated lands; D, delivery of debris to 

bays; E, relative precipitation. 

placer mining in the Sierra. In estimating 

these allowances account has been taken of 

variation in the activities which have contributed debris to the streams, of variation in the 

transporting power of the streams, and of variation in certain conditions that have tended 

to retard or prevent the delivery of debris in 

the bays. As most of these factors are to be 

discussed in following chapters they will be 

only briefly considered here. 

The output of mining debris increased in 

geometric ratio until the year 1884, wlfen it 

was suddenly checked, and since that time it 

has diminished, at first rapidly and then slowly. 

These facts are expressed in curve A of figure 5. 

The waste of the soil by rains, which under 

natural conditions was slow, has been greatly 

hastened by agriculture, by grazing, and by 

traffic over roads and trails. Its supposed 

history of variation is expressed by curve B. 

The debris brought to the bays is dominantly 

fine. Fine debris is also deposited on inundated lands, including the lateral basins of the 

Sacramen.to Valley, the delta marshes, and 

marshes bordering the bays. Therefore the 

bays receive only a fraction of the entire suspended load of the streams. The fraction has 

beeri varied by the construction of levees, the 

direct effect of which is to reduce the inundated 

area. In the Sacramento Valley the protection 

of tracts from inundation has raised the flood 

plane, and this has c·aused floods to spread over 

other tracts, so that the construction of levees 

has indirectly enlarged the inundated area. 

Clogging of stream channels by mining debris 

has also tended to increase the inundated area. 

The supposed history of the variation of the 

percentage of the fine debris carried to the 

b·ays is expressed by curve 0. 

Up to and somewhat beyond the epoch of 

most active hydraulic mining a part of the 

mining debris was temporarily deposited along 

the lines of stream conveyance, and the stores 

thus created were afterward drawn upon. The 

general effect of such stores was to delay and 

equalize transmission, causing the crest of the 

great wave of mining debris to reach the bays 

some years after it left the mountains, and 

giving the wave a broader and flatter profile. 

With the addition of this consideration to those 

involved in curves A, B, and 0, cu.rve D was 

constructed to represent in. general terms the 

history of the delivery of debris to the bays. 

The remaining factor of recognized im-

_portance. is the variation in the carrying power 

of the streams. The work of transportation 

has been performed chiefly by floods, and the 

efficiency of great floods is much higher than 

that of small floods. The greater floods of the 

rivers are associated with heavy rainfall, and 

it is during heavy rain that soil waste occurs. 

Because the records of floods are imperfect 

except for recent years, and because data as to 

heavy rains are not readily accessible, I have 

made use, instead, of precipitation records, 

which are published by the United States 

Weather Bureau in convenient form. Curve 

E in figure 5 shows for each .rainy season 
CHANGES IN THE CONDITION OF BAYS. 37 

(July 1 to June 30) the relative precipitation 

(in rain and snow) from 1850 to 1914. 

The transporting capacity of the streams 

depends largely .on the concentration of rainfoll into short periods, and the printed record 

tells little about such concentrations but the . ' relation of precipitation in the Sierra to 

cyclonic disturbances tends toward a sort of 

rhythmic concentration, and there is a rough 

c011.·elation between seasonal floods and seasonal 

precipitation. In a general way transporting 

capacity varies with precipitation, and it.varies 

in greater ratio than precipitation. On the 

basis of th:is law a set of factors of relative 

stream efficiency were derived from the data of 

relative precipitation, and these were multiplied, for the several annual seasons, by the 

ordinates of curve D. The products were then 

assumed to be proportional to the deli very of 

debris to the bays in the corresponding seasons. 

To the results of the computations thus made 

a further qualification was applied, to take 

account of special conditions affecting channel 

portions of the bay system. Carquinez Strait 

is essentially a channe~ for the flow of waters, 

an~ its de~th is determined automatically, 

bemg so adJusted that the traversing currents 

ma:y be able to transport sand along the bed. 

It IS probable that the strait received its 

principal deposit rather early in the h:istory of 

the mining-debris invasion and that later 

additions have been small. A similar statement applies to the central portions of the 

channels ~hrough Suisun and San Pablo bays. 

· The estimates of the total deposition in the 

bays for the period 1849-1914 are contained in· 

Table 5 

TABLE ~.~Estim_ates of the volumes of debris deposited in 

tl!e San FtanCUJco Bay system from 1849 to 1914, incluswe. 

Volume of 

Body of water. Dates of deposits Volume of 

surveys.' between deposits, 

dates of 1849-1914. 

survey. 

Cu. yds. Cu. yds. 

Suisun Bay ....... 1867-1886 64,000,000 200,000,000 

Carquinez Strait ... 1861-1890 40,000,000 50,000,000 

San Pablo Bay .... 1857-:1897 366,000,000 570,000,000 

San Francisco Bay. 1856-1896 196,000,000 326,000,000 

Bay system. ........... ........... 1,146,000,000 

These estimates take no account of subsidence, although it is probable that the period 

to wJ;Uch they ·pertain witnessed subsidence, 

especially of the crustal block west of the Haywards fault. If it were possible to make the 

proper allowance the estimates would be somewhat larger. 

The shoaling of the bays has been accompanied by a lessening of their areas. The salt 

marshes, whose margins are intimately associated with the lines of high tide, have steadily 

encroached on the muddy shoals, and the lines · 

of low tide have as steadily encroached on 

the areas of continuous open water. Such 

encroachm.ents diminish the tidal prism, on 

the magnitude of which depends the depth 

of entrance to . the Golden Gate, and their 

relations to foreign commerce give them 

special importance, but it is convenient to 

defer their consideration until estimates have 

been made of the total volume of the mining 

debris . 

. • 
• 

CHAPTER VI.-QUANTITY AND DISTRIBUTION OF DETRITUS. · 

DATA TO BE DETERMINED. 

Nearly all phases of the economic questions 

connected with the debris from hydraulic mining are concerned with quantities. It is desirable to know (1) how much detritus-gravel, 

sand, and clay-was excavat_ed by the miners 

and started toward or down the streams; (2) 

how much detritus the streams received from 

other sources; (3) what is the present distribution of this material; and (4) what changes 

are in progress and toward what results do they 

tend. The present chapter will consider the 

first three of these subjects. With reference to 

each of them there is a certain amount of definite information, but this falls so far short of 

complete knowledge that the field remaining 

for conjecture is regrettably large. The lack of 

satisfactory data has been shown by the wide 

diversity in the· earlier estimates, and the task 

of adding to re series of ill-supported and conflicting conjectures is not attractive. Nevertheless it is undertaken, first, because the contribution of a body of new measurements gives 

presumptive advantage to a new system of estimates, and second, because the importance of 

the question of quantities gives value to a 

demonstration of their order of magnitude, 

even where actual magnitudes may be only 

roughly approximated. I shall not hesitate in ' the pages that follow, to base estimates on 

personal judgment when no better foundation 

is available. 

QUANTITY OF MINING DEBRIS.l 

The belt of hydraulic mining in the Sierra 

Nevada traverses the drainage basins of a 

series of streams tributary to the Sacramento 

and the San Joaquin. On the tributaries of the 

San Joaquin the quantities of mining debris 

were relatively small-so small as to produce 

little or no effect on. the navigability of the 

rivers. On Feather River proper the mining 

operations were more extensive but still small 

1 A part of this text has already been printed with small verbal 

differences, as pp. 18-21 of U.S. Geol. Survey Prot Paper 73, 1911, The 

Tertiary gravels of the Sierra Nevada of California by Waldemar 

Lindgren. ' 

38 

as compared to those on the Yuba, the Bear 

and the American. Of the quantity of materiai 

excavated in the basins of those three rivers a 

number of estimates have been made, and the 

estimated amounts vary through a wide range. 

The latest estimate that makes use of first-hand 

data is given in the report of a board of Army 

engineers headed by Lieut. Col. W. H. H. 

Benyaurd. 2 The data were collected and discussed chiefly by F. C. Turner,3 assistant 

engineer, and apply to the year 1890. For the 

present purpose this estimate is the most aV"ailable, especially as it was made some years after 

the stoppage of general hydraulic mining, 

whereas a number of the earlier estimates were 

made during the progress of the mining! It 

constitutes part of the report of a detailed 

reconnaissance of the region of hydraulic 

mining, in which a large body of valuable data 

was accumulated. The method of making the 

estimate is not stated by Turner, but may be 

assumed to have been indicated in general 

terms in the following passage from the report 

of the board: 

The usual manner of estimating the amount of material 

moved is to determine the amount of water used, in 

miner's inches, and assign a duty to the inch. . This, however, varies in different localities, in some places being as 

low as 2,000 and in others as high as 2,600 cubic feet in 24 

hours. ·In the usual determination the quantity is taken 

at 2,230 cubic feet in that time. The duty depends upon 

the quantity of water used, the pressure, the character of 

the material washed, and the grade and size of the sluices; 

character of material and grade are the ruling elements. 

With heavy material the duty may be ·as low as 1.5 to 2 

cubic yards, and with light material as high as 10 cubic 

yards per inch. Instances are quoted in the report of the 

State mineralogist for 1889 where, with increased grade of 

sluices (12 and 18 inc~ gr~des), the duty attained was 24 

and 36 yards, respectively. The usual calculations are 

upon a basis of 3! cubic yards. It will therefore be seen 

that great variations must exist in the estimates of amount 

of material that has already been mined out. 

Impressed by the uncertainty of this mode of 

estimation, in which no engineer appears to 

have reposed great confidence, I undertook to 

check it by an independent estimate based on 

2 Chief Eng. U. S. Army Ann. Rept. for 1891, pp. 2996-3118. 

a Idem, pp. 3041-3087. 
QUANTITY AND DISTRIBUTION OF DETRITUS. 39 

an entirely different procedure, namely, the 

measurement of the cubic contents of the 

cavities produced by the excavation. This 

work was carried on in the spring and autumn 

of 1908, and after a few preliminary experime.nts the following 1nethod was adopted and 

followed: 

The surveying instruments were a plane 

table and a stadia rod. With these a traverse 

was run through the bottom of each cavity or 

along its edge, and where the area was large a 

tra~erse circuit was completed. ·From the 

stations of the traverse numerous p<;:>ints were 

detennined by stadia and others by angulation, 

the position and altitude of each being fixed. 

A co1nplete sketch was 1nade of the rim or outer 

margin of the excavation, and for a short distance outside the rin1 the ground was contoured. The scale adopted· was 200 feet to 1 

inch, and the contour interval was 20 feet. 

After the completion of the field work the contours of the ground previous to the excavation 

were restored by esti1nate, · use being made of 

the determined contours outside the rim and of 

the determined courses of drainage lines outside the ri1n. With the aid of these restored· 

contours an·d the determined points within the 

area of excavation a series of cross sections 

were constructed, and from these the volume of 

the excavation was cq1nputed. Some of the 

features of the excavated cavities are illustrated by Plate X. 

'fhe precision of this method can not be defi-· 

nitely stated, as there were no absolute checks 

on the accuracy of the restored con tours; and 

. the data controlling the restoration varied in 

cogency through a considerable range. In the 

opinion of the writer, who was also the surveyor, the general accuracy is such that the 

grand totals are true within 10 per cent, 

although many individual measurements have 

a lower precision. 

The work was not carried on through the 

entire hydraulic district, but comparison with 

the Turner estimate indicates that it covered 

about four-fifths of the excavation in the basin 

of Yuba River and three-sevenths of the total 

excavation of Yuba, Bear, and American 

rivers. The table on page 40 gives the results 

in some detail and also compares them, so far 

as practicable, with the items of the Turner 

estimate. The difference in n1ethod of estimate led to a. difference in the classification of 

the excavations, so that the comparison can 

not be refined, ht~t it serves nevertheless as an 

effective check on the Turner estimate. 

Examination of the table shows that a few 

of the earlier estimates are higher than the 

later, but the majority fall below and the new 

general totals exceed the earlier by 51 per 

cent. · The difference is in part explained by 

the fact that some mining took place in the 

interval between 1890 and 1908. A number 

• of mines were worked for short periods or in a 

small way under permits from the Debris Commission, and there was some surreptitious 

work without permits. During the surveys 

in 1908 it was easy to see that certain parts of 

the excavations, on which a young forest 

growth had sprung up, were of early date, and 

that other parts, still bare of vegetation, were 

relatively recent; but it was not practicable 

either to infer dates with approximate accuracy 

or to estimate separately the more recent 

work. It is believed, however, that the work 

subsequent to 1890 ·can account for only a 

small part of the discrepancy between the two 

estimates, and that the greater part of the 51 

per cent of difference inheres in the methods of 

estimation and the data employed. Assuming 

the substantial accuracy of the later estimate, 

and assuming further that the ratio of difference derived from the totals of the table may 

be applied as a correction to the other parts of 

the Turner estimate, I have deduced revised 

estimates for the total hydraulic excavation in 

the combined Yuba, Bear, and American 

basins. Turner's summary is as follows: 1 

Material excavated by hydraulic mining in 

the basi.n ofCubic yards. 

Yuba River ............................ 452, 690, 000 

Bear River ........................... 234, 650,000 

American River ....................... 170, 330, 000 

857,670,000 

The application .of the ratio 1.51 to these 

quantities yields for the Yuba basin 684,000,000 

cubic yards, for the Bear basin 354,000,000 

yards, and for the American basin 257,000,000 

yards. The values thus derived have been 

adopted for the Yuba 'and American basins 

but have not proved satisfactory for the Bear 

basin. The quantity of mining debris accumulated in the canyons of the Bear and its 

tributaries has twice been estimated with more 

1 Chief Eng. U.S. Army Ann. Rept. for 1891, pt. 5, p. 3080. 
40 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

care than was bestowed on similar deposits 

along the other rivers, and something is known 

also of the volume of the river's piedmont deposit. (See p. 48.) When these estimates 

are considered in connection with the small 

discharge of the Bear and other factors affecting the ratio of the local arrest of debris to the 

total output of the mines, good reason is found 

The only other stream to receive mining debris and convey it eventually to the Sacramen to is. the main branch of. the Feather 0 

Ttirner's estimates do not include the mines of 

its b.asin, and my own observations covered but 

a small area. W. H. Hall/ in 1880, estimated 

the "water used and rna terial w~shed out per 

annum" . for the several river basins of the 

TABLE 6.-Volume of hydraulic excavation in part of the Yuba River basin as estimated by G. K. Gilbert in 1908 and by 

F. C. Turn;r in 1889-90. · · 

[Excavation expressed in thousands of cubi? yards.] 

District, mine, or locality and excavation therein. 

1908 

Camptonville (7,100), Youngs Hill (7,500), 

Galena Hill (4,400), Weeds Point (3,000). 

Indian HilL .................................. . Moores Flat (21,000), Orleans Flat (3,400), Snow 

Woolsey Point (3,900). Flat. ...... ________________________ , __ . 

Badger Hill and English Co ........... ~ ... -- .. . 

North Bloomfield (main pit, 64,400; minor pits, 

13,600). 

North Columbia (main pit, 89,500); Howleys, 

Ohio, Neversweat, etc. (2,560). Union GraveL. _______ . ____ ._ ... __ ........... . 

Yuba (Grizzly) ...... _--·- ______ ._._ ......... . Paterson and vicinity ____ -. - -.......... : . .... . North San Juan (25,350), Manzanita and American (47,900), Bed Rock (10,050), Buck Eye 

(12,650). 

Esperance (and Kinney) ..... -............... . French CorraL _______ . _ . __ . _ . __ .............. . 

Omega ............. ____ ~---·-. __ .............. . Alr.ha and vicinity ....... __ .. _ ............... . Sa1lor Flat and Blue Tent .................... . Cement Hill(?)---------------- ............... . Rough and Ready, Randolph Hill and vicinity .. Nevada City (Manzanita or Sugar Loaf, 6,000; 

1889-90 

Willow Creek and Camptonville (5,800+ 

1,500). Indian HilL. ______________ ...... · ........ __ .. 

Moores Flat, Orleans Flat, and Snow Point._ .. 

Woolsey Flat .. _ . ___ .. _ . _ . _ .. _ ............. . 

Badger Hill and Cherokee (10,000), English 

Co. (7,000). 

North Bloomfield (29,000) Last Chance, 

Porter, etc. (3,000). 

Columbia Hill (20,000+20,000) .... -.......•• 

Union GraveL ...... __ --- __ .... __ ._._.-·-_ .. . Grizzly HilL ... _. __ . ______ . __ . _ . _ ........ __ . 

Paterson claims (5,000), Montezuma Hill (500) 

North San Juan and part American (20,000+ 

500), Sweetland Creek, Birchville, Manzanita and part American (60,000). Esperance .. ________ ._ .. _ .. ____ .. _ .. ___ .. ___ . French CorraL _______ . ___ . _ .. ______ . _ .... _ .. Omega._ .. _. _____ .. ___ ... _ .. ____ . _. __ . _ . _ ... 

Alr.ha (5,000), Place, Merrill, etc .. _ ...... __ . Sallor Flat and Blue Tent.. _______ .. _ .... _ .. 

Nevada City, Cement HilL ........ --. __ ... _. Rough and Ready, Randolph HilL ...... __ . Nevada City, Sugar Loaf. _________ ..... ·: .. __ 

Hirschman, etc.; 6,400). 

Murchies, McCutcheon, Oharonnat, etc......... Murchies, Gold Flat, etc.--~ ............... -. Scotts Flat.._ ... _. ___ . _ . . . . . . . . . . . . . . . . . . . . . . . Scotts Flat .. _ .............................. . Smartsville and Timbuctoo (24,460), Mooney Smartsville, Timbuctoo, and Mooney Flat. __ Flat (3,800). Sicard Flat .. _. ______ . _ . . . . . . . . . . . . . . . . . . . . . . . Sicard Flat.-- ............................. . 

~~h~~:Ji~iii _-_-_-_-_-:: : : : : : : : : : : : : : : : : : : : : : : : : : : . ~ ~ ~d~~~~: : ~ -_ -_-_- _-: : : : : : : : : : : : : : : : : : : : : : : : : : : 

Two miles west of Parks Bar Bridge ............... -.do .... ~ ..... : ......................... . Dry Creek ......................................... do .. -............................... -.. Two miles west of Grass Valley ..................... do.- .................................. . 

Percentage ..... _. __ .......................... _ .......................................... . 

Total excavation. 

1908 1889-90 

22,000 7,300 

7,800 4,500 

28,300 26,000 

20,700 4,100 

22,600 17,000 

78,000 32,000 

92,060 40,000 

9,100 10,000 

1;400 1,000 

"7, 800 5,500 

95,950 80,500 

3,500 1,500 

16,050 31,000 

22,700 12,000 

9,000 7,000 

46,200 15,000 

1,800 2,550 

910 3,000 

12,400 10,000 

2,100 500 

18,600 12,000 

28,260 44,800 

3,030 1,700 

3,900 .......... 2,700 ............ 320 . ................. 

40 . ............... 

30 .. .............. 

557,250 368,950 

151 100 

for regarding the estimate of 354,000,000 cubic 

yards as excessive. As all the quantities involved in the discrepancy were subject to considerable uncertainty, the adjustment was of 

the nature of a compromise, and the correction 

assigned to the estimate of output of debris was 

a deduction of 100,000,000 cubic yards, reducing the estimate to 254,000,000 cubic yards. 

Sierra from the American northward. For the 

basin of the Feather the estimate of material 

washed is 12,687,500 cubic yards, and the sum 

of the estimates for the Yuba, Bear, and American is 36,480,500 cubic yards. Lieut. Col. 

Mendell 2 makes a similar ~stimate for the 

1 California State Eng .. Rept. for 1880, pp. 23-24. 

2 Chief Eng. U.S. Army Ann. Rept. for 1881, pp. 2486-2487,2494-2501. 
.QUANTITY AND DISTRJBUTION OF DETRITUS. 41 

year 1880 in which the corresponding figures 

are 4,407,770 and 31,070,094. Mendell also 

gives with full detail the assessors' returns· of 

the water used in mining. Hall and Mendell 

both qualify their estimates-Hall because his 

data were incomplete and Mendell because the 

method was unsatisfactory. In 1881 the canyons and mining regions of tho Fe a thor and 

tho Yuba were inspected by Marsden Manson, 

and his report 1 tends to discredit tho estimates based on assessors' returns. He found 

that much of the water ascribed to hydraulic 

mining was actually used in drifting and 

quartz mining and in other ways not involving · 

tho handling of largo quanti ties of earth. 

Disregarding for the moment Manson's implied criticism, accepting the estimates of Hall 

and Mendell, and ·assuming further that the 

·total ~:mtput of de.bris for the several basins 

for tho whole period of hydraulic mining was 

proportional to the annual output, I have 

made two computations of the total output 

of tho Feather. The figures quoted from Hall's 

table give 366,200,000 cubic yards, and tho 

figures from Mendell's table 186,600,000 cubic 

yards. The details reported by Manson and 

Turner, as well as data from other sources, indicate the probability that both these figures 

are excessi~.e. On the other hand, a minimum 

estiina.to is suggested. by the volume of the 

piedmont deposit of the Feather, which occupies the river bed between Oroville and Marysville. I-Iall estimated this, from surveys probably n1ado in 1879, at 18,257,000 yards,2 and 

tho observations of Turner indicate that only 

1noderato additions were n1ade in the following 

decade. Tho suggested minimun1 is 40,000,000 

cubic yards, and this might serve as a practical 

estimate, so far as conditions of the lower river 

are concerned; but it would probably not be 

coordinate with tho estimates for the other 

basins, which aim to show the full extent of 

the exploitation of the auriferous deposits. 

According to Manson, most of the tailings 

fr~:nn the greatest operations were lodged in a 

permanent way in the American Valley, an 

opening in the h~art of the mountains. Between tho limits 40,000,000 and 186,000,000 

cubic yards, the value of 100,000,000 cubic 

yards is arbitrarily chosen. Adding the estiDlate for tho· Feather basin ~o that for the 

1 Chic£ Eng. U.S. Army Ann. Rept. for 1882, pp. 2604-2612. 

s California State Eng. Ropt. for 1880, p. 11. 

three basins farther south gives a total of 

1,295,000,000 cubic yards as the output of the 

hydraulic mines on streams whose waters join 

the Sacramento. · 

With reference to problems connected with 

the flow of mining debris there is no occasion 

to discriminate between the tailings of the 

hydraulic mines and the waste from three 

other sources-ordinary placer mining, placer 

drifting, and quartz mining. All through the . 

auriferous belt the initial mining was done 

with pick, shovel, and cradle, and only a small 

quantity of tailings resulte.d from the work 

of each miner, but the miners were an army. 

They attacked first the gravel bars of creeks 

and rivers and the associated low-lying alluvial 

terraces (see Pl. XI), and gradua).ly extended 

their activities to the unconsolidated formations that sheathed or composed tho hills. 

The material was worked over with the aid of 

water, the pebbles and boulders were left on· 

the ground, and the finer particles were washed 

away, for the most part quickly reaching the 

river. So far as the deposits were stream bars, 

the fine stuff that floated off was soon after- · 

ward replaced by the streams, so that there 

was no permanent local loss of material, and 

there seems to be·no occasion to take account 

of such washings in this connection. It was 

different, however, with the washings on the 

hillsides. The pits thus excavated still remain, 

and the material removed has been added to 

the detrital load of the streams. The cradle 

was soon supplemented by appliances that 

used water to better advantage, and the system of work in which excavation is accomplished by a powerful jet of water-the system 

that has appropriated as its title the comprehensive adjective hydraulic-was gradually 

developed. Where the hill deposits were deep 

the earlier work· was superficial. or marginal, 

and the rims of its shallow pits were effaced by 

the greater operations that followed. In this 

way a portion of the volume of pre-hydraulic 

work came to be included in·the measurement 

of hydraulic pits and is thus covered by the 

revision of tho Turner estimate. To conlplement that estimate allowance should b.e made 

only for the shallow excavations remaining 

outside the areas of the hydraulic work. 

The data are vague. In travE}rsing the Yuba 

mining region on various errands and especially 

in the search for outlying hydraulic pits hidden . 
42 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

in the forest, I often came across shallow workings. .At half a dozen localities the evidence 

of placer work was almost continuously visible 

for a mile or 'more; at numerous localities it 

was seen for only a few rods·. Usually the view 

was obstructed· by forest or chaparral, so . that 

casual observation gave little information as 

to areal extent. An arbitrary estimate of 10 

square miles ·for the entire Yuba area includes 

not only tracts that were imperfectly seen 

but many other t.J;acts assumed to be distributed through the hillsides of the basin. It 

is estimated that earth was removed from this 

area to an average depth of 3 feet; and these · 

assumed· dimensions give as the estimated 

total volume of the debris 30,000,000 cubic 

yards. As the basins of the Bear and American 

together nearly equaled that of the Yuba in 

hydraulic output, the same volume of placer 

debris is ascribed to them. 

The large expense of drifting, as compared to 

surface washing, tends to limit the extent of 

operations, but its waste is of the same character as that from hydraulic washings except 

· that it includes more boulders. The mining . 

of quartz veins, however, produces much waste 

of a type unsuited for transportation unless it 

is dumped directly into the streams. Ordinarily the mine refuse is so coarse and angular 

that it lies permanently where it is originally 

thrown; and only the ore that is milled goes to 

swell the load of the streams. An estimate of 

the debris from drifting might therefore be 

based on the volume of the mine openings, 

and an estimate for quartz mining on the work 

of the stamp mills. The statistics of the stamp 

. mills, though irregular and discontinuous, give 

the amount of ore crushed for a number of 

individual years and yield, with generous 

interpolation, an estimate of 35,000,000 cubic 

yards for the whole mining b.elt from the 

Feather to the Tuolumne. To this I add 

15,000,000 yards as an allowance for unmilled 

mine waste dumped directly into streams or 

otherwise finding its way to them, thus raising 

the estimate for quartz-rriining debris to 

50,000,000 yards. There are practically no 

statistics of the output of debris from drifting, 

and the allowance of 30,000,000 cubic yards 

which I make is a mere guess. It does not 

include the output for the basin of the Feather, 

which was practically covered in estimating 

the debris from hydraulic mining. 

Two other bodies of d~bris remain to be considered. A few of the hydraulic mines of the 

Sierra are on streams which belong to the 

general hydrographic basin of the Sacramento 

but do not send their detrital loads either 

directly or in any considerable share to that 

river, because they discharge directly to one 

or another of the lateral overflow basins of the 

Sacramento Valley. Their debris belongs to 

the general total for the mining industry of the 

Sacramento River basin but has little if any 

connection with the "debris problen1." A 

greater number of mines are associated with 

rivers south of the American that are not 

tributary to the Sacramento but send their 

waters either to the San Joaquin or to the delta 

plexus east of the mouths of the Sacramento 

and San Joaquin. The debris from these 

rivers has no recognized connection with the 

problem of the economic treatment of the 

Sacramento but may affect economic problems 

in t;he tidal waters of the bays. 

The only important group of mines sending 

debris to the lateral basins of the Sacramento 

Valley are on Table Mountain Creek, north of 

. Feather River, and their output is estimated 

at 25,000,000 cubic yards. An allowance of 

5,000,000 cubic yards is added for mines on 

Butte Creek, north of Table Mountain, and 

creeks between Bear and American rivers. 

The hydraulic mines south of the American, 

discharging tailings to Cosumnes, Mokelumne, Calaveras, Stanislaus, and Tuolumne 

rivers and to a group of creeks between the 

Cosumnes and Mokelumne, were the subject 

of a critical examination by Lieut. A. H. 

Payson 1 in 1880. He reported that profitable 

hydraulicking was limited by natural conditions in much of the region, that local storage 

of tailings was practicable at many points, 

that the damage to farming lands, although 

noteworthy, was far less than in the Sacramento 

River basin, and that the injury to navigation 

was very small. He made a detailed estimate of 

the annual output of the mines, placing the total 

at 7,352,465 cubic yards. In 1889 or 1890 C. L. 

Higgins 2 examined the same district for the 

Benyaurd commission. He found that only 

minor changes had taken place in the condition of farming lands affected by the debris, 

1 Chief Eng. U. S. Army Ann. Rept. for 1881, pp. 2501-2514; idem for 

1882, pp. 2584-2604. 

2 Idem for 1891, pp. 3114-3118. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XI 

A. WORKED-OVER DEPOSITS IN THE BED OF A RAVINE. 

The coarse g1·avel was stacked on the ground, and the finer stuff washed to a neighboring river. 

B. OLD "DIGGINGS" ON A GENTLE SLOPE OR "FLAT." 

The fertile soil was washed away, and reforestation is a slow process. 

EXHAUSTED PLACER DIGGINGS. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XII 

A. LITTER OF PINE NEEDLES IN A FOREST. B. LITTER OF MANZANITA LEA YES IN A THICKET OF BUSHES. 

NATURAL PROTECTION AGAINST SOIL WASTE. 

The blanket of dead leaves with which trees and bushes cover the ground is usually more e~cient than the living foliage, and always more efficient than the roots, 

in protecting the soil from waste. The movement of soil is initiated by the blows of ra.indroP.s, and the leaves receive the blows. It is greatly promoted by the 

concentration of the rain sheet into rills, and the leaf blanket obstructs the formation of nlls. Compare with Plates XIII and XIV. 
A. CONSERVATION OF SOIL BY A CLOSE GROWTH OF GRASS. 

This sloping meadow is irrigated by a ditch that follows its upper edge. Short lateral ditches descend the slope at 

intervals of 20 feet. Tlie ends of two laterals appear in the view. Sometimes the water of the ditch carries mud, 

and at such times the grass acts as a strainer, separating and arresting the mud. A double ridge has been created 

by the deposit along the line of each lateral. The grass also :prevents the gathering of the water mto rills. Receiving the water in a system of artificial rills, the grass causes 1t to spread uniformly over the land. Compare with 

Plate XIV. 

B. THE ATTACK OF RAIN ON BARE GROUND. 

Because the direction of rain is usually downward the erosive effect of a single shower is not easily discriminated from 

the effects of previous rains. For this reason the power of rain as an agent in soil waste is apt to be underestimated. In this instance the raindrops were carried by a strong wind that swept obliquely up the slope from 

right to left. All previous rain records were obliterated and a series of furrows having the trend of this particular rain were carved . The exact duration of the rain is not known, but the storm of which it was a feature 

lasted only a few hours. 

SOIL PROTECTION AND THE ATTACK BY RAIN. 
U.S. GEOLOGICAL SURVEY 

A. A FIELD ON THE WESTERN SLOPE OF THE SIERRA. 

A rainstorm lasting three days drenched the field after it had been plowed and 

harrowed. In flowin" off the water gathered into rills, which washed away 

soil, leaving such gullies as appear in the foreground . The water also carried 

fine soil from the general surface, but the effect of this removal is shown in the 

picture only by the cleanness of the stones. The soil thus wasting under 

artificial conditions was developed under theprotection afforded by a pine forest. 

Compare Plate XIII, A. 

PROFESSIONAL PAPER 105 PLATE XIV 

B. A FIELD ON AN EASTERN SLOPE OF THE BERKELEY HILLS. 

The records of cultivation and of rain are lacking, but it is evident that the little 

gullies were excavated by rain-made rills after the harrowing. In its natural 

condition the slope, despite its steepness, waa protected from soil waste by 

grass. The hill consists chiefly of rock, and the soil created under the vegetal 

covering by the decay of the rock is now in process of removal. 

SOIL WASTE DETERMINED BY AGRICULTURE. 
QUANTITY AND DISTRIBUTION OF DETRITUS. 43 

and he estimated the annual output of the 

hydraulic mines at 4,348,600 cubic yards. 

One of these estimates preceded and the other 

followed the great restriction of mining by 

injunctions, but the restriction appears to 

have been n1uch less in the southern field than 

in the northen1. 'faking these estimates at 

their face value and applying them, with what 

appears reasonable .qualification, to the whole 

period of placer and hydraulic mining, I deduce 230,000,000 cubic yards as an estimate 

of the entire body of earth moved from its 

original place to the present time in the region 

frmn Mokelumne River to Tuolumne River, 

inclusive. 

The estimates brought together in Table 7 

cover a period closi.p.g with the year 1909, 

which was the last year of my personal.observation in the region of ·the mines. No definite 

data are a;,ailable for the five years that have 

followed, but it is believed that a proper allowance would increase the totals by less tlian 

10,000,000 and possibly by less than 5,000,000 

cubic yards. 

TABLE 7.-Sttmmary ojmining debris, 1849-1909. 

Million cubic yards. 

From hydraulic· mining in basin ofUpper Feather River ....................... . 

Yuba River ................................. . 

Bear River ................................ . 

American l~iver ............................ . 

100 

684 

254 

257 

QUANTITY OF D£BRIS FROM SOURCES OTHER 

THAN MINING. 

Besides mining, the chief sources of detritus 

in the rivers are agriculture, roads and trails, 

grazing, and the natural wash of the soil. A 

similar influence is commonly ascribed to deforestation, and in some regions this is a cause 

of much soil waste, but within the field of 

my personal. study of the Sierra deforestation without agriculture or grazing is a negligible factor. The protective efficiency of bushes 

is there practically the same as that of trees, 

and by their growth a deforested surface is 

quickly reclothed and effectually shielded. 

(See Pl. XII.) 

In attempting to evaluate the non-mining 

detritus I have made a special study of a single 

district, the drainage basin of Yuba River, and 

then extended the results to other districts by 

aid of inferences based on evident differences 

in local conditions. 

AGRICULTURE. 

The farmer destroys all vegetation except 

. that which he sows or plants, and the only protection against rain which his soil receives is 

that a.fforded by the plants he cultivates. (See 

Pis. XIII and XIV.) Many of these are set so 

far apart that their protection is slight. Some 

constitute a good shield during part of the year 

but leave the ground bare for the remainder. 

Streams tributary to lateral basins of. Sacra- · 

men to River ............................. . 

Mokelumne River to Tuolumne River, inclusive ........... ; ...................... . 

Prom ordinary placer mining ..................... . 

:From quartz mining (one-fourth in Sacramento 

basin) ........................................ . 

30 Only a few give shelter comparable with that 

of a natural growth. The rains consequently 

wash great quantities of earth from farming 

lands, and the contrast between agrieultural 

·and natural conditions is strong. To realize 

~~ it, one has only to compare during a moderate 

rainstorm the rills of muddy water that flow 

from a cultivated field with the clear rills from 

land in its natural condition. There are indeed methods of cultivation by means of which 

soil waste may be almost eliminated, but they 

are not yet extensively used in the Sacramento 

basin. 

230 

60 

:From drifting (three-fourths in Sacramento basin) .. 

Total mining d~bris: 

From hydraulic mining ....................... 1, 555 

From all mining tributary to Sacramento River 1, 390 

From all mining tributary to Suisun Bay... . . . 1, 665 

T'o most ~aymen, and possibly to some engineers not concerned with great movements of 

earth, the term 1,000,000 cubic yards conveys 

no definite meaning. It helps us to a conception of the actual magnitude of the hydraulicnlining operations of the Sierra to know that 

the volume of earth thus moved was nearly eight 

ti1nes as great as the volume moved in making 

the Panama Canal. 

To learn the area of farming land in the 

mountain and foothill part of the Yuba River 

drainage basin, I made inquiry of the county 

assessors and learned that in 1908 it was about 

50,000 acres. For this area I· estimate an 

average loss of 2 inches. There are no sta-
44 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

tis tical data for abandoned farms; I estimate 

their area at 15,000 acres, with an average loss 

from the surface of 4 inches. These es.timates 

give for the tribute of the total waste from 

existing farms 13,000,000 cubic yards and from 

the abandoned farms 8,000,000 cubic yards, a 

total of 21,000,000 cubic yards. But not all 

of this waste has reached the streams; a portion has lodged in stable deposits on gentler 

slopes, especially on meadows; and an allowance of 3,000,000 cubic yards for these lodgments leaves 18,000,000 cubic yards as the 

estimate of the addition to the load of the 

streams. The period during which this addition has been made is the same as that to 

which the mining waste pertain~. 

ROADS. 

In the foothill part of the Yuba River basin 

very few of the roads are so nearly level as to 

escape wash. · In their grading and by their 

use the ·natural vegetation is destroyed, so 

that the surface is exposed to rains and running 

wat~r. Moreover, the wheels and hoofs grind 

the soil, converting it to dust in summer and 

to mud in the rainy season, with the result that 

it is easily washed away. And the ruts and 

side drains concentrate flowing water that 

would otherwise be widely diffused. (See Pl. 

XV.) In many places the gullying of a road 

has so int~rfered with its use that a new track 

has been laid out at one side, and in some places 

a dozen or more of these tracks rna y l;>e seen. 

Where a new track can not readily be made and 

the original course is repeatedly restored to a 

passable condition by repair, the road surface 

may be lowered year by year until the track 

comes to pass through a miniature canyon. 

Much the greater part of the materia~ thus excavated finds its way to the streams, but there 

are two fractions which do not. Some of the 

dust rises into the air and is carried to neighboring land and, so far as it falls on chaparral or 

in forest, receives the same protection as the 

ground beneath. And· there are side-hill roads 

systematically drained at points so near together that the outflowing mud-laden storm 

streams, being too feeble to carry the coarser 

parts of their loads to a distance, build stable 

deposits close by.· 

The roads outside the mountains are i1ot included in the present estimate. Those in the 

higher parts of the mountain area are also 

omitted, because whatever detritus is washed 

from them is caught by the lakes which there 

interrupt the courses- of the streams. In the 

intervening district of mountains and hills the 

mapped public roads have a total length of 920 

miles. From these I estimate an average loss 

of 1 foot in depth over an average width of 10 

feet, and I assume that 85 per cent of this 

reached the streams. The unmapped roads 

and private roads are estimated to have about 

the same aggregate length, and the aggregate 

loss from these is estimated to be one-fourth as 

great. There are also obsolete roads, the sites of 

which have been reoccupied by forests. Their 

extent is unknown, and· there may be much 

error in the estimate that their aggregate tribute 

to the streams was one-fourth as great as that of 

the existing roads. These assumptions give for 

the mapped public roads 1,600,000 clibic yards, 

for the unmapped and private roads 400,000 

cubic yards, for the obsolete roads 500,000 cubic 

yards, a total of 2,500,000 cubic yards. 

TRAILS. 

The trails of the country affect the debris 

output in precisely the same manner as the 

roads. Their use and their grading destroy 

the natural protection; they catch and concentrate the flow of water on the surface; they frequently become gullied so as to be difficult of 

passage, and new lines are opened at the side. 

(See Pl. XVI.) Their aggregate length in the 

Yuba River basin is greater than that of the 

roads, but their area is less, and here also account should be taken of those that are obsolete as well as of those in use. Their tribute 

to the Yuba is roughly estimated at 800,000 

cubic yards. 

GRAZING. 

Ordinary grazing of the forest land and meadows of the Sierra-such grazing as is consistent 

with permanent occupation by horses and cattle-seems to have but a slight effect on the 

mineral outwash; and as all the land areas are 

or have been grazed it has not been found possible to discriminate outwash depending on 

grazing from the natural outwash. Therefore 

no estimate is made for it in this paragraph. 

Overgrazing, on the other hand, has a very 

notable effect on the outwash. (See Pls. XVII 

and XVIII.) Along the main lines of travel 
A. A ROAD IN THE SIERRA AT AN ALTITUDE OF 2,000 FEET. 

The sunken passage through which the road runs was eroded by storm waters. The road intercepts and guides the 

waters, and the traffic on it facilitates their work by preventing the accumulation of forest litter. The traffic usually breaks up the structure of the earth, converting a coherent body into sand or dust, which is easily washed 

away. 

B. A SIDE-HILL ROAD IN THE FOOTHILLS OF THE SIERRA. 

The :litch dug to intercept storm water from the hill and thus keep it from the wheel ruts has been enlarged by 

action of the water, and the earth removed from ditch and road has gone to a neighboring creek. 

EROSION OCCASIONED BY ROADS. 
A. A CATTLE TRAIL IN THE SIERRA. 

This trail, by intercepting storm water as it flowed down a gentle slope, created a strong rill that carved a channel 

through the thin soil cap. The cattle then avoided this line and made parallel trails at the side. The excavated 

soil was carried to a near-by river. 

CATTLE TRAILS FOLLOWING THE CREST OF A GRASS-COVERED RIDGE AND DESCEND! TG 

AT ITS END. 

Erosion by storm water is made po£sible by the killing of the grass and is promoted by concentraticn of the ilow in · certain trail grooves. 

EROSION OCCASIONED BY TRAILS. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XVII 

A. A FIELD NEAR COLFAX ORIGINALLY CLOTHED BY FOREST AND AFI'ERWARD BY GRASS. 

Sheep in transit between mountain and valley pastures lingered here and consumed the grass, leaving the ground 

bare. Deprived of its protection, the soil was washed away· and the subsoil gullied by storm waters. Compare 

with Plates XII and XIII. 

B. A FIELD NEAR NEVADA CITY AT ONE TIME COVERED BY GRASS. 

Its present condition resulted from the extermination of the grass by overgrazing. 

EROSION OCCASIONED BY OVERGRAZING. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XVIII 

A. A GRASSY HILLSIDE NORTH OF THE GOLDEN GATE. 

The slopes were developed by the slow processes of nature, soil being produced by rock decay and its sculpture regulated by a close blanket of grass and other herbs. The balance of conditions havin~ been upset by excessive 

grazing, the sculpture of a new system of slopes has beaun. The initial gully of tne new regime has sharp 

edges, because the remaining grass still gives the smface a power of resistance greater than that of the 

earth beneath. 

B. A TRENCHED MEADOW IN THE SIERRA. 

This meadow, interruptin."l the course of a small stream, had for untold centmies arrested the fine silt washed 

from neighboring hil s. Its mat of vegetation was destroyed by grazing and the stream then began the 

excavation of the accumulated silt. The fence stands on a terrace at the level of the original meadow. 

EROSION OCCASIONED BY OVERGRAZING. 
QUANTITY AND DISTRIBUTION OF DETRITUS. 45 

meadow lands, whether fenc~d or unfenc~ed, are 

apt to be overgrazed, and the result is the complete or .approximate destruction of the herbaceous mat and an attack on the meadow deposit by the small stream flowing through it. 

In some places the 'entire deposit unde:flying 

the meadow has been washed away; in many 

other places it has been deeply gullied. On 

hill slopes overrun by herds of sheep in transit 

from range to range the vegetal protection is 

likely to be so nearly obliterated that the soil 

washes away or is deeply dissected by gullies. 

Some of the upland meadows used for summer 

· grazing by sheep are also subjected to gUllying, 

but these need not be considered here, because 

whatever earth has been washed away has been 

caught by the upland lakes. For the product. 

of overgrazing within the Yuba River basin I 

estimate 1,000,000 cubic yards. 

NATURAL DEGRADATION OF THE SURFACE. 

As hun1a.r1 agency has affected the entire area 

the natural outwash can not be deduced from· 

any direct observations, but over the greater 

pa.r·t of the region natural influences are modified only by ordinary grazing. From such 

lands there is an appreciable outwash of material, which may be observed in the occasional 

discoloration of storm water as it flows toward 

the streams. In some localities the arrangenlent of long ditches, which contour the slopes, 

is such as to catch a portion of this outwash 

and accumulate .it in reservoirs farther on. 

(See Pl. XIX.) The material thus gathered 

eventually fills the reservoirs, and in many 

places it has been excavated one or more tin1es 

for the purpose of restoring the capacity of the 

reservoirs. No attempt was made to measure 

either the catchment areas tributary to such 

reservoirs or the rate·of accumulation, but the 

observations show that the natural outwash, 

with such acceleration as it receives from grazing, is a notable factor in the carrying of detritus to the streams. In estimating the amount· 

of outwash for the Yuba district, since 1849, at 

10,000,000 cubic yards, I an1largely influenced 

by a comparison of the local conditions with 

those of the Mississippi River basin, for which 

a general e'3timate is afforded by Humphreys 

and Abb<?t's measurements of the river's sedi-

·mentary load. 1 

1 Humphreys, A . .A., and Abbot, H. L:, Report upon the physics and 

hydmulicll of the Mississippi River, 1861. 

SUMMARY. 

The estimates for the non-mining waste in 

the Yuba area since 1849 are summarized as 

follows: Agriculture; 18,000,000 cubic yards; 

roads, 2,500,000; trails, 800,000; overgrazing, 

1,000,000; and ordinary grazing plus natural 

waste, 10,000,000; a total of 32,300,000 cubic 

yards. The district to which this estimate applies has an area of about 1,000 square miles. 

Treating this district as representative of the 

mountain and foothill part of the Sacramento 

River basin, I have .based on it estimates for 

other districts. In making these estin:iates I 

have assumed, first, that the waste from farming land has been proportional to the average 

acreage for the period of occupation; second, 

that the waste from roads, trails, and overgrazing has been proportional to the average 

population; and, third, that the natural waste 

and waste from ordinary grazing have been 

proportim~al to ~ea .. The resultihg estimate 

for the entire basin, except the valley lands, is 

360,000,000 cubic yards. 

In estimating the waste from the valley lands 

the same assumptions were made, and account 

was taken also of the fact that, with the same 

exposure to stqrm action, the valley lands lose 

much less than the hill lands, by reason of their 

gentle slope. Because of the infinite grada-: 

tion of slopes in both provinces, a satisfactory 

integration of the slope factor is impossible, 

and there are no quantitative observations 

on relative outwash. The numerical relation 

actually assumed was that the waste from 

valley lands, under similar conditions, has been 

one-tenth that of hill lands. The resulting 

estimate of the total waste from valley lands is 

60,000,000. cubic yards, making a total of 

420,000,000 cubic yards for the non-mining 

waste of the Sacramento basin during 65 years 

beginning with 1850. 

Two groups of tracts were omitted from the 

computations because they have furnished no 

waste to the river.· These are, first, the tracts 

which drain to lakes and whose waste has been 

caught by the lakes; and, second, the annually 

inundated basins of the Sacra.mento Valley, 

which instead of contributing to the river's 

waste have arrested a portion of it. 

A similar estimate has been made of the nonmining waste from the San Joaquin . River 

basin, the Yuba estimates being combined, as 

before, with data of area, pop~lation, cultiva-
46 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

tion, and slope, and also with data of precipitation and run-off. Because rainfall is lighter 

and run-off less copious in the San Joaquin 

River basin than in that of the Sacramento, 

the waste of ·exposed soil is presumably less 

rapid. The result of the estimate is 280,000,000 

cubic yards. Its addition completes the estimate of waste in the area tributary to Suisun 

Bay from the beginning of placer mining to the 

present time. 

TABI,E 8.-Surnmary of waste from the land surface of the 

Sacramento and San Joaquin basins from 1850 to 1914-.a 

Tributary to Tributary to Sacramento 

River. Suisun Bay. 

Cubic yards. Cubic yards. :Mining debris .. __________ 1,400,000,000 1,675,000,000 

Non-mining waste ....... 420,000,000 700,000,000 

1,820,000,000 2,375,000,000 

a In transferring the figures for mining debris from Table 7, 10,000,000 

cubic yards was added as allowance for the period 1909-1914. 

DISTRIBUTION OF THE DETRITUS. 

· Of the entire body of waste that has been disturbed from its original position only a part has 

come finally to rest. The remainder has lodged 

by the way in temporary deposits. Deposits 

consisting almost wholly of mining debris were 

arrested in the canyons and valleys of the 

mountains, and these are partly permanent but 

chiefly temporary. Piedmont deposits likewise consisting mainly of mining debris are 

likewise largely temporary. The ·channels of 

the valley rivers contain other temporary deposits. Permanent deposits are lodged in the 

lateral basins of the lower Sacramento and the 

Feather and on the delta marshes of the Sacramento and the San Joaquin. Deposits which 

are chiefly permanent rest in the bays and in 

the ocean. 

The estimates of the deposits in bays, of the 

deposits in the channels of valley rivers, and of 

the largest piedmont depos{ts have a basis of 

measurement, but these estimates together account for iess than two-thirds of the entire 

amount of waste. The estimation of the other 

deposits is a matter of apportionment. In the 

study of the problem of distribution attention 

was given first to the items with quantitative 

control, and considerations affecting the relative magnitude of other items. were then 

brought to bear; but for purposes of presentation it is more convenient to follow approximately the order of position, taking up in 

sequence the deposits of the Sierra, the piedmont, the valley rivers, the bays, the ocean, 

and the valley lands. 

DEPOSITS WITHIN THE SIERRA NEVADA. 

Marsden Manson 1 in 1879 examined the 

canyons of the Yuba and estimated that they 

contained 25,577,000 cubic yards of mining 

debris. This estimate covered only the debris 

lodged in the canyons and included neither. the 

accumulations in the valleys of the upland 

creeks nor the mining dumps. Eleven years 

later F. C. Turner 2 went over the same ground, 

finding that only 6,170, 750 cubic yards remained in the canyons. All these canyons are 

traversed by large streams discharging from the 

higher parts of the range, and after the checking of hydraulic mining their accumulations of 

gravel were rapidly washed out. Turner also 

reported on the upland creeks, estimating their 

deposits at more than 18,000,000 cubic yards, 

but this estimate explicitly omitted Deer Creek 

and apparently did not include the hillside 

mining dumps. My own observations, made 

chiefly in 1908, after a further lapse of 18 years, 

were incidental to other work and covered only 

a part of the ground; but thei enabled me to 

check the work of Manson and Turner at several 

points and also to compare the conditions 

which they found with a later condition. The 

canyon deposits, greatly reduced in 1890, were 

nearly gone in 1908. Some of the creek deposits had been eroded near their heads but 

had elsewhere been increased, and the mining 

dumps above the creek beds, though everywhere trenched, were still of formidable volume. I made no attempt at measurement-in 

fact an adequate evaluation was then impossible without borings-but I derived the impression that the quantities calculated or 

estimated in 1879 and 1890 were greatly 

exceeded by the deposits occupying creek 

valleys and hill slopes in 1908. This impression 

was afterward fortified by studies (set forth in 

the following chapter) on the rate of delivery 

of debris to the piedmont deposit, and the 

estimate I have adopted is independent of 

those of Manson and Turner. Brought down 

1 California State Eng. Rept. for 1880, pp. 58-61. 

2 Chief Eng. U. S. Army.Ann. Rept. for 1891, pp. 3058-3059. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XIX 

A. RESERVOIR ON HERRING CREEK, A TRIBUTARY OF STANISLAUS RIVER. 

This reservoir received drainage from about 11 square miles of woodland and meadow, ranging in altitude from 8,000 

to 9,500 feet. The natural condition of the land surface was modified chiefly by grazing. After the emptying 

of the reservoir its silt deposit was partly washed away by the creek. Photographed in 1905. 

B. A HILLSIDE NEAR SMARTSVILLE. 

Altitude, 900 to 1,100 feet. A water ditch contours the slope at midheight. Soil waste from the upper slope repeatedly 

clogged the ditch, causing breaks and the erosion of the lower slope. 

PHENOME A INCIDENTAL TO OVERGRAZING. 
QUANTITY AND DISTRIBUTION OF DETRITUS. 47 

to the year 1914, it ascribes to the mo.untain and foothill portion of the Yuba River 

basin a debris volume of 65,000,000 cubic yards. 

This material is chiefly in the beds of the upland creeks and in the mining dumps, but a 

portion is stored behind perishable dams. 

The debris lodged along Bear River and its 

tributaries was estimated in 1878 by E. C. 

Uren at 88,977,160 yards.1 Mendell quotes 

from the testimony in a mining suit (1878) an 

estimate of 88,000,000 cubic yards. Turner, 3 

accepting Uren's estimate in the main, questions 

one portion as probably too large by 10,000,000 

yards and gives 66,051,000 yards as the result 

of his own examination in 1890. It is not 

clear from his statement whether he included 

all the mining dumps, but as most of the mines 

of this district cast their debris directly into the 

streams this question is not important. An 

estimate of 60,000,000 cubic yards as the present quantity allows something for the amounts 

held behind storage dams. 

Manson, 2 in 1882, estimated the debris along 

North Fork of American River at 20,000,000 to 

25,000,000 cubic yards and stat~d that there 

, was a smaller quantity on Middle Fork and 

none on South Fork. In 1890 Turner 4 esti...: 

mated North Fork deposits at 34,661,541 cubic 

yards, but part of his data were observations. 

by Uren in 1881. For Middle Fork he ·estimated 10,000,000 to 15,000,000 cubic yards, 

but with a qualification tending to reduce the 

amount. Only the canyon deposits are mentioned in his descriptions, but the general 

character of the slopes indicates that the deposits outside the canyons were not large. I 

have no information of later date, and an estimate of 30,000,000 cubic yards is arbitrarily 

·assigned to represent the present status. A 

sin1ilarly arbitr.ary estimate of 15,000,000 yards 

is made for the Feather River basin. An 

estimate of 95,000,000 cubic yards for the mining region south of the American River area is 

an apportionment of the total output of 

230,000,000, the assignment being influenced 

by the fact that a number of the larger mines in 

that ·region are on small streams of so low a 

gradient that their operation is limited by deficient outfall, by the fact that the Cosumnes 

and Calave~as, not heading in high• mountains, 

1 Chief Eng. U. S. Army Ann. Rept. for 1891, p. 3068. 

2 Idem for 1882, p. 2572. 

a Idem for 1891, pp. 3063, 3068. 

4 Idem for 1891, p. 3073. 

71139°-17---4 

have small discharge, and by the fact that the 

piedmont deposits of this region are small. 

The total estimate for the debris deposits 

within the Sierra is 265,000,000 cubic yards. 

. DEPOSITS OF THE PIEDMONT BELT. 

The largest of the piedmont deposits, that of 

the Yuba, is also the one with which I am best 

acquainted. It heads within the mountain 

cany~n a short distance above the mouth of 

Deer Creek and ends at Marysville, 21 miles 

below, where the Yuba joins the Feather. Near 

the foot of the "narrows" (see Pl. IX B ' ' 

p. 28), at a point nearly 2 miles from its head, 

the deposit was sounded in connection with a 

project for a dam and was found ·to. be 85 feet 

deep. Half a mile farther downstream its thickness probably exceeds 100 feet. At Marysville 

it is 15 to 25 feet thick. The surface width, 260 

to 300 feet at the narrows, expands gradually to 

nearly 14,000 feet at a point 6 miles from the 

Feather. Thence to the Feather the main 

body narrows, being limited by levees, but a 

thinner division continues or increases the 

width. Its volume has been ~ariously estimated, but I quote only the estimate of Maj. 

W. W. Harts, who for several years, as a member of the California Debris Commission, had 

immediate charge of engineering works at the 

locality. The value he assigned in 1906 is 

333,000,000 cubic yards. 5 A computation of my 

own yielded an estimate somewhat larger, but 

I prefer his result, because the data at his command were exceptionally full. 

Since the date of his observations the deposit 

has received an addition in consequence of the 

completion of a barrier at Daguerre Point 

(p. 62) but has suffered loss from the scouring 

of a deeper channel near its head (p. 28). and 

also between Daguerre Point and Marysville. 

The net change has probably been a small loss, 

and the volume in 1914 is estimated at 

330,000,000 yards. Of this quantity rather 

more than half, as judged by the reports from 

borings, would be classed as gravel, about onefourth as sand, and the remainder as silt; but 

this classification is qualified by the fact that 

much of the gravel contains a very large admixture of sand. 

The deposit on Feather River heads at the 

canyon n1outh at Oroville and extends down-

~ Am. Soc. Civil Eng. Proc., vol. 32, p. 104, 1894. 
48 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

stream about 25 miles, terminating in the slack 

water occasioned by the debris brought to the 

river by the Yuba. Its volume was estimated 

in 1879 by W. H. Hall 1 at 18,256,22·2. cubic 

yards, and I am not acquainted with any subsequent estimate. Reports have been made, 

however, of increase in depth near the head 

and also of extension downstream. The present volume is roughly estimated at 25,000,000 

cubic yards. Mendell 2 quotes an estimate of 

the Bear River deposit made by "experts" in 

1878, the amount being 36,000,000 cubic yards. 

The Benyaurd commission 3 made the same 

estimate in 1890. I am led to make a larger 

estimate, not from later or better observations 

on the ground but as part of an adjustment 

between discrepant data. The estimates that 

have been made of the output of the mines 

near Bear River, of piedmont deposits, and of 

the deposits above the piedmont, when compared, indicate a percentage of arrested material much smaller than in the deposits of the 

Yuba and the American, although the small 

discharge of the Bear would lead one to anticipate a larger percentage. Of the three estimated quantities, the volume of the deposits 

above the piedmont seems most trustworthy, 

and I have accordingly reduced the·estimate of 

output, as already mentioned, and increased 

that of the piedmont deposit, raising it from 

36,000,000 to 60,000,000 cubic yards. The area 

of the piedmont deposit of American Ri:ver is 

given by Manson 4 as 6,ooo· acres and its depth 

at 5 to 30 feet. These figures apply to the year 

1880, and subsequent change has caused areduction. The estimate of 60,000,000 cubic 

yards, here used, corresponds to a mean depth 

of about 6.5 feet. To the piedmont deposits of 

more southerly streams a volume of 70,000,000 

cubic yards is assigned; and the total of estimates of piedmont deposits is 520,000,000 cubic 

yards.· ' 

DEPOSITS IN THE VALLEY RIVERS. 

In 1879 Hall 5 estimated the quantity of 

detritus in the bed of Feather River below the 

mouth of the Yuba at 32,211,871 cubic yards 

and in the bed of Sacramento River below the 

mouth of the Feather at 83,346,913 cubic yards. 

1 California State Eng. Rept. for 1880, pp. 10, 11. 

2 Chief Eng. U.S. Army Ann. Rcpt. for 1882, p. 2572. 

a Idem for 1891, p. 3006. 

4 Idem for 1882, p. 2573. 

5 California State Eng. Rept. for 1880, pp. 10-14. 

The Benyaurd commission made a series of 

cross sections of the Sacramento in 1889 and 

estimated the addition during the preceding 

10 years at 25,000,000 cubic yards. An elaborate survey has since been made by the 

California Debris Commission, but the results 

are not yet in a form convenient for comparison. We may infer, however, from the changes 

in the low-water planes, as exhibited in figure 4 

(p. 30), that the deposit is about as deep near 

the mouth of the Yuba as in 1879 but has 

suffered a net loss near the mouth of the 

American, and a reduction of Hall's figures · 

corresponding to these data gives 96,000,000 

cubic yards as an approximate estimate of the 

deposits in both valley rivers at present. 

There are two other river tracts which have 

undoubtedly received deposits but in which 

navigation has not been impeded and in which 

no measurements have been made. These are, 

first, that part of the Sacramento channel above 

the mouth of the Feather in which slack water 

has been caused by the deposit of sand brought 

by the Feather, and second, the tidal sections 

of the San Joaquin and of the tributaries that 

join it in the delta. An allowance of 4,000,000 

cubic yards for these assumed deposits brings 

.the total estimate for the filling of valley rivers 

to 100,000,000 cubic yards. 

DEPOSITS IN THE BAYS AND IN THE OCEAN. 

. The deposits in the bays, the volume of 

which was estimated in the last chapter, consist chiefly of .mud, but not all the mud delivered by the rivers comes to rest in the bays. 

The most finely divided portion remains in 

suspension while the river water is traversing 

the chain of bays and escapes at last to the 

ocean. Another portion, although deposited 

on shoals of the bays, is lifted again by the agitation of the water whenever wind storms 

sweep the bays and in this manner makes the 

journey to the ocean by a series of stages. If 

one views the ocean from some commanding 

high point when the tide is ebbing from the 

Golden Gate, he can usually-perhaps always-see that the outflowing stream is distinguished from the water it invades by a yellowish tinge, and the same tinge is recognized 

by the approaching mariner. 

A portion of the discolored water returns to 

the strait along with the succeeding flood tide, 

but another portion remains in the ocean. 
QUANTITY AND DISTRIBUTION OF DETRITUS. 49 

The relative magnitude of the two portions is 

determined for each tidal cycle by the temporary condition of the local currents of the 

ocean, but when long periods are considered the 

volume permanently given to the ocean differs 

little from the volume ef water which the bays 

receive from the streams of the land. (The 

equation of outflow with inflow is qualified 

only by evaporation from the bays and by 

rainfall upon them.) This relation makes it 

possible by means of systematic sa~pling of the 

effiuent water, to obtain a valuable estimate 

of the quantity of debris delivered in suspension to the ocean, but the investigation has 

not been made. We have, in fact, no information more definite than the impression conveyed by casual observation of the discoloration, which is faint compared to the turbidity 

of a land stream during flood. The volume of 

the e:ffluen t wa tor is so great, however, that 

even a faint discolora-tion may represent the 

annual transportation of millions of tons of 

debris. In order to discharge annually 1,000,-

000 tons of mud the ratio of suspended matter 

in the wa tor of the Golden Gate need be only 

one six-hundredth as great as its average ratio 

in Colorado River at Yuma. 

An independent train of debris, consisting of 

particles too large for suspension, follows the 

bed of tho channel that traverses the chain of 

bays. Tho channel is maintained chiefly by 

tidal currents, which regularly alternate in direction, and the same currents move the debris 

forward and backward over the bed. The ebb 

CUI'rents have the greater strength, and the 

net result of the movement of the debris to anci 

fro is. an advance toward tho ocean. The advance is most rapid when the rivers are in 

flood, and the activity of transportation at 

such times is shown by changes in the configuration of the channel beds. Through Suisun 

Bay and Carquinez Strait the material of the 

channel beds, as observed by soundings and 

recorded on the charts, is sand with scattered 

patches of mud, and this description applies 

also to the northern part of San Francisco 

Bay, but a peculiar condition is found in San 

Pablo Bay. Near the head there is a rapid 

change from sand to mud, and for a distance 

of 8 miles the charts record only mud as the 

material of the bottom. As already mentioned (p. 35), and as explained more fully in 

Chapter IX, there is reason to believe that the 

chief part of this "mud" is derived from the 

suspended load, here precipitated by the process of flocculation. The material includes also 

a portion of fine sand, presumably derived 

from the bottom load, and both mud and sand 

are moving forward toward the ocean. N othing coarser than fine sand seems. to pass this 

point, and it is believed that the stream of 

sand' from the rivers here practically comes to 

an end. Both sand and gravel from the 

Sierra ·have been consumed by attrition as 

they were rolled by the currents and have 

been thus transferred to the suspended load, 

with the exception of a residuum of fine sand, 

and this remnant has been ground so small 

that little of it can survive the buffetings of a 

journey from San Pablo Bay to the ocean. To 

avoid reiteration this important conclusion is 

here stated somewhat baldly; it is in fact the 

outcome of a careful study, and the subject is 

discussed at length in the chapter on conditions affecting the bar at the entrance to San 

Francisco Harbor. 

Any estimate of the tribute of debris to the 

ocean is, with present information, necessarily 

arbitrary. The estimate which will be usedfor the period 1849-1914-is 50,000,000 cubic 

yards. 

DEPOSITS ON VALLEY LANDS AND DELTA 

MARSHES. 

The lateral basins of the Sacramento Valley 

and the marsh lands of the delta region are inundated, except for the interference of levees, 

when the rivers are in high flood. The turbid 

water of inundation loses velocity in traversing 

these lands, and part of its suspended load is 

deposited. When a levee breaks, the torrent 

which rushes across it carries sand also from 

the river channel, and the sand is deposited on 

the inundated land. Here, too, may be included the debris caught by the tidal marshe~ 

bordering the bays, debris which comes in part 

from neighboring creeks. It would be difficult 

to measure the debris thus arrested in 65 years, 

and the attempt has not been made. 

If the estimates of volume made for deposits 

in the mountains, rivers, bays, and ocean are 

subtracted from the total estimated volume of 

mining and non-mining debris, there remains 

for the deposits of the inundated lands an esti-
50 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

mated volume of 294,000,000 cubic yards. As 

this volume is composed chiefly of fine silt 

which has been carried in suspension, it may 

properly be compared with the volume of the 

silt deposits of the bays and the ocean. Of the 

1,146,000,000 cubic yards of deposits estimated 

for the bays about 1,050,000,000 cubic yards 

is silt, so that .the estimate of silt for bays and 

ocean together is about 1,100,000,000 cubic 

yards. Not all of this was in suspension when 

the debris was fed to the valley rivers, for a 

portion came from the comminution of sands 

in transit; but the ratio of suspended load to 

bed load was large in the period of most active 

mmmg. If one-fourth of the 1,100,000,000 

cubic yards came from the comminution of 

coarse debris, there would remain 825,000,000 

cubic yards to be compared with the 294,000,000 

assigned to the inundated land, and we may 

roughly check. the scheme of estimates by inquiring whether it is admissible to assume that 

the inundated lands caught rather more than 

one-fourth of the fine silt that came to the rivers . . m suspension. 

It is probable that during a flood of exceptional magnitude considerably more than 

one-half of the silt-bearing water leaves the 

river channels and moves with relative slowness across valley lands and marshes.1 The 

greater part of the diverted water returns 

to the channels in a few days; a minor part 

may be held in a nearly stagnant condition 

for weeks. Ordinary floods spread much less 

water over the lowlands, ahd the water is 

diverted for shorter periods. Normally the 

waters of great floods are more highly charged 

with silt .than those of ordinary floods, but 

low-stage waters are silt-free. It is not improbable that under normal conditions more 

than half of the river water that is well charged 

with suspended debris is diverted from the 

channels and during its loitering journey parts 

with a large share of its load. During the era 

1 Clapp, Murphy, and Martin (Am. Soc. Civil Eng. Trans., vol. 61, 

p. 317, 1908) estimate the mean run-off from the Sacramento drainage 

basin for tho four days of maximum flood in March, 1907, at 554,700 

second-feet, which is equivalent to 4,404,000 acre-feet in the four days. 

The California Debris Commission (62d Cong., 1st sess., H. Doc. 81, 

pp. 8-9)estimatesthetotalcapacity of five flood basins of the Sacramento 

Valley (omitting the sixth) during the floods of 1907 and 1909 at 4,022,000 

acre-feet. The capacity of the river channel at Knights Landing is estimated at 10 per cent oft he flood discharge, and corresponding estimates 

for points below the mouth of Feather River and the mouth of American 

River are 14 per cent and 15 per cent. These estimates take no account 

of the diversion of flood waterstodeltalands. San Joaquin River, with 

a flood discharge half as great as that of the Sacramento, has no lateral 

basins but overflows extensive delta marshes. 

of extensive hydraulic and other placer mining 

the fine tailings were given to the rivers in all 

seasons, and a very large amount wa~ carried 

forward during river stages so low that none 

escaped from the channels. This abnormal 

condition, though adding greatly to the total 

output of silt, did not add proportionally to 

the deposition on valley· and delta lands. 

The considerations thus outlined do not yield 

quantitative results, and I can only say of them 

.that they contain nothing evidently inconsistent with the idea that the inundated lands 

caught rather more than a fourth of the suspended load of the rivers. 

Table 9 gives a summary of the estimates as 

to the present distribution of the entire body 

of mining and non-mining debris. The deposits 

in the mountains, on the piedmont slope, and 

in the channels of valley rivers contain little 

besides mining debris. Non-mining debris 

enters largely into all the others. · 

TABLE 9.-Estimates of the f]istribution in the year 1914 of 

debris moved by mining operations or by rains from lands 

draining to the San Francisco Bay system during the preceding 65 years. · Million 

cubic yards. 

Deposits within the Sierra Nevada................ 265 

Piedmont deposits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520 

Deposits in the channels of valley rivers. . . . . . . . . . 100 

Deposits on inundated lands, including tidal 

marshes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 

Deposits in the bays ............................. 1,146 

Deposits in the ocean............................ 50 

2,375 

NEW WASTE FROM OLD MINES. 

After the miners' jets have ceased to play on 

the walls of hydraulic mines the waste of the 

walls is continued for a long time by natural 

agencies. Vegetation, the great conservator of 

unconsolidated formations, does not quickly 

assume control, because the material lacks 

humus and is infertile. Rain, frost, and the 

flow of storm water detach and move the component particles, and the cliffs are gradually 

wasted. Taluses are formed, and graded 

slopes are established on which the debris is 

regularly transported. In some , mines the 

system of slopes is such that much of the newly 

detached debris is stored within the mining 

cavities. From other mines the greater portion is freely discharged. Many decades will 

elapse before these bluffs of earth have acquired 

stable slopes and are clothed by protective vegetation. The cliff faces of the central hill of the 
QUANTITY AND DISTRIBUTION OF DETRITUS. 51 

Manzanita mine, pictured in Plate X (p. 29), 

had been exposed to the weather more than 20 

years when their condition was recorded by the 

camera and were still bare and barren, with 

only a moderate building of talus. The softer 

formation of the North Bloomfield cliff, shown 

in the same plate, attacked by streams as well 

as by rain, had in 20 years been elaborately 

. sculptllred but did not yet approach a conclition of stability. 

N·o serious atte1npt has been made to estimate the volume of debris contributed to the 

creeks and rivers in this manner. All that had 

escaped from the mines before 1908 was included in the estimates of mining debris based 

on the measurement of mining cavities. The 

subsequent output and the future output have 

not been covered by any of the estimates of 

waste, but some account will be taken of them 

in another connection. 
CHAPTER VII.-STUDIES ON THE LOWER YUBA. 

The piedmont deposit of the Yuba is the trol of the.river and the impounding of a por- · 

largest single body of mining· debris outside of tion of its detrital load. One of these works, 

the bays. Some of its "features are portrayed called barrier No. I, was located about 1 mile 

in Plates IX (p. 28) an4 XX, and figure 6 shows below Parks Bar Bridge, at a point where the 

its horizontal extent. Because of the great flood channel of the river is about 1,500 feet 

injury wrought by it and of the further injury wide. (See fig. 6 and Pl. XXIII, p. 58.) The 

threatened, it has received special attention :first part of the barrier, about 6 feet high, was 

from the engineers charged with the duty of completed in 1904, and the second part, incontrolling the movements of the debris. Some creasing the height by 8 feet, in 1905. The bed 

of the engineering works executed during the of the river at this point had been raised, during 

period of my own investigation ·have served, a series of decades, by a deposit of which the 

through their reactions, to illustrate matters of depth is not less than 50 feet; and the material 

FIGURE 6.-0utline map of the piedmont deposit of Yuba River. 

importance to river science, and I have availed 

myself of the opportunity to study the reactions. 

In part, but only in part, the studies have immediate applic~tion, yielding results that are 

used in the present paper. They are recorded 

in this chapter without special reference to 

their applications. 

DETRITAL LOAD OF YUBA RIVER. 

The report of the California Debris Commission- for 1899 1 outlines a project for various 

works on the Yuba piedmont plain for the conI 56th Cong., 1st sass., H. Doc. 431. 

52 

serving as foundation for the barrier was gravel 

with generous admixture of sand. For a short 

distance at the north an earthwork was constructed, with a crest above the highest flood 

stage; for the remainder of the distance the 

crest of the dam served also as a spillway, and 

this part was 1,250 feet long. The project ·of 

the dam involved· the building of a series of 

units, each unit increasing the height 6 or 8 

feet. In the construction of the :first unit several rows of piles were driven into the gravel, 

the spaces between them were filled by quarry 

rock and gravel, and the crest was protected by 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XX 

A. THE DEBRIS PLAIN NEAR ITS BROADEST PART, AS SEEN FROM DAGUERRE POINT, ON 

THE NORTH BANK, IN 1905. 

The greatest thickness of the deposit included within this view is 40 feet . 

B. LEVEE BUILT TO EXCLUDE RIVER FLOODS FROM MARYSVILLE AND VICINITY AND TO 

LIMIT THE DEBRIS INVASION. 

At this point the levee is 25 feet high. An arm of the debris plain is seen at the left. Photographed in 1005. 

THE PIEDMONT DEPOSIT OF THE YUBA. 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXI 

Tllis unit included a flat crest (on which a man is stand ing), a foreslope of double curvature, and a horizontal apron. 

The vimv shows a system of piles placed for the support of the second concrete unit. The first unit was completed 

in 1904. The photograph was made June 6, 1905. The floods of the intervening winter and spring had filled 

the new-made reservoir with debris. They had also excavated the river bed on the downstream side of the barrier, so that the apron, originally at the level of the bed, now stood several feet above it. At this stage of the barrier's 

hlstory the :first contour map of the river bed was made. 

B. THE COMPLETED STRUCTURE. 

The second unit was added during the low-water stage of 1905. It included a flat concrete crest and a curved foreslope 

connecting with the lower unit. The photograph was made during the passage of a flood, January 17, 1906. 

BARRIER NO. l, YUBA RIVER. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXII 

A. REMNANT OF THE DEBRIS DEPOSIT ABOVE THE BARRIER, EXPOSED IN SECTION AFTER 

THE BREACH! G OF THE BARRIER. 

The coarse gravel at top is a veneer; the gravel below contains much sand. The :resistant ledges visible near the bottom 

of the slope contain clay. Photographed June 11, 1907. 

B . VIEW DOWNSTREAM FROM THE BARRIER, SEPTEMBER 19, 1906. 

A year earlier the river bed had the level of the bench seen at the right. The subsequent erosion was in part selective. 

Large stones remain, but finer material was wa-shed away. The gravel of the foreground is no~ representative 

of the whole deposit, but only of its coarsest elements. 

I 

ASPECTS OF DEBRIS AT BARRIER NO. 1, YUBA RIVER. 
STUDIES ON THE LOWER YUBA. 53 

a sheet of concrete that curved forward and The map work by Mr. Baker in 1905 was exdownward and was continued downstream in a tended half a mile below the barrier, and this 

short horizontal apron. (See Pl. XXI.) portion was also surveyed in the fall of 1906 by 

rrhe basin created by the first unit was filled Mr. Nelson. The purpose of the extension was 

by the river with detritus, chiefly gravel, during to determine such changes in the configuration 

the ensuing winter, and the piles for the support of the river bed below the barrier as might be · 

of the second unit were driven into and through occasioned by the addition to its height. 

this gravel. It was during the progress of the The "barrier was afterward breached and 

last-mentioned work that I first visited the destroyed by the flood of March, 1907, wherelocality. It appeared that an opportunity was upon the OJ.'iginal profile of the river channel 

here afforded to obtain information on an ob- wa~ immediately restored.~· Only a few remsctu·e question in river hydraulics-the amount nants of the deposit artificiaUy induced .by the 

of detrital load transported near the bottom of barrier survived (Pl. XXII, A), but their presthe current-and measures were immediately ervation gave opportunity for observations 

taken to utilize the opportunity. The plan in- that supplemented the data obtained from 

eluded two surveys of the bed of the river for borings by Mr. Murphy. 

a distance above the barrier, one before the From the discussion of these various data the 

completion of the second unit, the other after following results were obtained: 

the floods of the river had brought down their The initial slope of the river bed in the viload of detritus and the heavier portions of it cinity of the barrier was about 16 feet to the 

had been arrested in the basin. In the autumn mile, and there was a rapid increase upstream 

of 1905 a plane-table map, with 2-foot contour to 22 feet to the mile. This marked difference 

interval, was made by S. K. Baker, of the was probably of a temporary character, as it 

reclamation branch of the Survey, and a short was not indicated in a profile constructed by 

time afterward the addition to the barrier was the California Debris Commission in 1899 nor 

completed, raising the sill over which the water by the contours of the United States Geological 

flowed 8 feet. A portion of this map is repro- Survey map of 1909; but apart from temporary 

duced in Plate XXIII (p. 58). . accidents there·is a general correlation of slope 

The first flood after the completion of the . with coarseness of detritus in the portion of the 

work occurred in January, 1906, the maximum river bed lying outside the mountain canyons. 

stage being reached on January 18. (See Pl. At Marysville, near the mouth of the river, 

XXI, B.) The stage was somewhat higher where the chief material is sand, the slope is 

than other high stages of the winter season, and about 6 feet to the mile, and it increases upthe flood continuedfor a week. A visit to the stream as the material changes successively to 

locality after the flood had nearly subsided coarse sand, fine gravel, and coarse gravel. 

showed that the basin above the barrier had The erection of the first 6.feet of the barrier in 

been nearly filled by the work of that flood, and 1904 caused a filling duri~g the flood stages of 

a resurvey was therefore made (by Mr. Baker) the ensuing winter which extended at least 1! 

as soon as the stage of the river permitted. It miles upstream and probably somewhat more, 

was not practicable to follow the methods used reducing the average slope in that region to 

about 12 feet to the mile. When the second at low water, and instead of attempting con- unit was added to the barrier, increasing its tow."S, a series of cross sections were run at inter- vals of 500 feet. height 8 feet, deposition again began, and the 

flood of January, 1906, in filling the newly Other floods followed during the winter and formed basin, extended its deposit upstream 

spring, and at the low-water stage in the au- about 1! miles, reducing the average grade for 

turon of 1906 a second contour map was made that distance to about 9 feet to the mile. The 

(Pl. XXIV), the work being done this time by subsequent s~orms of the same winter extended 

C. L. Nelson, a topographer of the Survey. the ·area of fill somewhat farther upstream and 

Dw.·ing the summer of 1906 a series of shallow nearly restored the slope of 12 feet to the mile 

borings were made by E. C. Murphy for the · which had been created by the floods of the pre .. 

purpose of ascertaining the character of the ceding winter. 

deposit, and especially the distribution within The completion of the upper unit of the barit of sand, fine gravel, and coarse gravel. rier created immediately a basin of. slack water, 
54 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

and the first deposit made by flood waters in 

this basin was of fine material, chiefly sand but 

also silt, these materials being afterward found 

at the bottom of. the deposit near the barrier. 

Farther up the initial deposit' was chiefly of 

gravel, and the gravel deposit was gradually 

extended downstream, so as to cover the sand. 

There was, however, a triangular area near the 

barrier not reached by the principal current, 

and here no gravel was deposited. When the· 

surface of the deposit was first examined ~fter 

the January flood. it was found that fine gravel 

had been transported to the crest of the barrier, arid it was thus shown that during the latter part of that flood not only_sand but a certain amount of gravel had passed over the barrier. When the work of the season's floods was 

completed, a coarser gravel had extended its 

area to the barrier, but not the coarsest of all; 

and the presence of this coarser gravel at the 

crest and the vigorous erosion which had taken 

place on the concrete facing of the barrier 

showed that a large body of gravel had passed 

downstream. The deposit as measured therefore did not include the entire annual load of 

coarser material carried by the stream, but only 

. a fractional part. The flood of March, 1907, 

which was of exceptional magnitude, br,ought 

down to the barrier the coarsest type of gravel 

seen in the river bed, and we may therefore 

assume that it raised the slope of the river bed 

above the barrier to an angle which would have 

been stable; but the full record of this grade 

was prevented by the destruction of the barrier. 

The erosion of the concrete facing by the gravel 

passing over it was great, amounting along the 

belt of' principal action to an average of several 

inches and completely piercing the 18 inches 

of concrete at some points. This erosion was 

one of the causes to which the destruction of the 

barrier was ascribed by engineers. 

The whole body of material arrested by the 

barrier in the winter and spring of 1906, as 

computed from a comparison of the contour 

maps made before and after that period, was 

1,690,000 cubic yards. Of this total 920,000 

cubic yards was arrested during the January 

flood. In the following table it is classified as 

silt, sand, and gravel. These terms are somewhat loosely used, and the lines of separation· 

are not sharply drawn. In a general way, 

material of which the largest particles would 

pass a sieve having 80 meshes to the inch is 

called silt; material of which the largest particles would pass an 8-mesh sieve is called sand; 

and all material involving larger particles is 

called gravel. The gravel exhibits a wide 

range of constitution, the larger pebbles in some 

portions being less than an inch in diameter 

and the boulders in others being more than 1 

foot. In some thin and local layers pebbles 

or boulders are segregated, with only enough 

finer material to fill the interstices; but such 

patches are comparatively rare, and the great 

body of the gravel is. an intimate mixture of 

coarse and fine materials, in which the finer 

predominate and constitute a matrix for the 

coarser. 

TABLE 10.-Material (in thousands of cubic yards) arrested 

by barrier No. 1, Yuba River, between October, 1905, and 

October, 1906. 

Period. Silt. Sand. Gravel. Total. 

Flood of January, 1906 ...... 5 260 655 920 

Subsequent floods ........... 5 30 735 770 

10 290 1, 390 1,690 

There was no measurement of the quantity 

of material passing over the barrier during the 

same period, and the total detrital load of the 

river at this point therefore can not be determined in an altogether satisfactory way, but 

an estimate.has been made. · 

The fact that the flood of January, 1906, 

brought to the crest of the barrier no material 

coarser than fine gravel, although the upstream 

portion of the deposit included a large body of 

coarse gravel, indicates that nearly all the 

gravel that was in transit in January was 

caught by the barrier. As the amount of 

gravel arrested at that time has been measured, it is feasible to estimate the quantity of 

gravel transported in the entire year, if a suitable comparison can be made between the 

efficiency of the January flood and that of the 

floods which followed it. 

Competent data as to the relative magnitudes of the floods are fortunately at hand, 

but information as to the relation of discharge 

to efficiency is less satisfactory. One of the 

.regular g~ging stations of the Survey-the 

Smartsville station-is on the Yuba about 5 

miles above the barrier. From daily observations of river stage at that station the corresponding discharges have been computed, and 

Table 11 contains the daily discharges during 

the flood periods under discussion. 
STUDIES ON THE LOWER YUBA. 55 

TABLJ~ H.-Discharge of Yuba River during periods of high 

water between Oct. 1, 1905, and Oct. 1, 1906.a 

Day. Discharge. Day. Discharge. 

Sec. feet. Sec. feet. 

Jan. 13 ......... 16, 900 Apr. 23 ........ 8, 600 

14 ........ 11, 500 2<! ........ 7, 650 

15 ........ 18, 900 25 ........ 6,800 

16 ........ 18, 900 26 ........ 7, 050 

17 ........ 16, 900 27 ........ 7,000 18 ........ 48,000 28 ........ 6,450 

19 ........ 33,000 29 ........ 7,350 

20 ........ 13,000 30 ........ 7,800 21. ....... 9,000 May 1 ........ 9,000 

22 ........ 6,810 2 ........ 10,500 

23 ........ 5,550 3 ........ 12,400 

4 ........ 11,600 

Feb. 15 ........ 10,200 5 ........ 13,000 

6 ........ 12,500 

19 ........ 11, 100 7 ........ 12,500 

20 ........ 5, 550 8 ........ 12,500 

21. ....... 10, 700 9 ........ 13, 600 

22 ........ 6, 810 10 ........ 13, 200 

23 ........ 7,850 11 ........ 14,400 

24 ........ 7,850 12 ........ 11,400 

25 ........ 8,230 13 ........ 8, 600 

26 ........ 6,810 14 ........ 9,300 

27 ........ 11, 100 15 ........ 10,000 

28 ........ 9,000 16 ........ 6,950 

Mar. 1 ........ 6,810 17 ........ 6, 700 

2 ........ 5, 550 18 ........ 6,500 

3 ........ 7, 150 19 ........ 6,800 

4 ........ 6,480 20 ........ 7, 200 

21. ....... 7, 150 

11 ........ 5,550 22 ........ 7,000 

12 ........ 28,400 23 ........ 6, 500 

13 ........ 12, 500 24 ........ 5, 750 

14 ........ 12, 500 25 ........ 8, 900 

15 ........ 9,400 26 ........ 18, 700 

16 ........ 7, 150 27 ........ 18,200 

17 ........ 6, 160 28 ..... · ... 20, 100 

29 ........ 13, 700 

21. ....... 5, 850 30 ........ 10,000 

22 ........ 16,400 31. ....... 8, 800 

23 ........ 18,400 June 1 ........ 8, 900 

24 ........ 29, 400 2 ........ 9,350 

25 ........ 26,400 3 ........ 10, 500 

26 ........ 30,400 4 ........ 25, 600 

27 ........ 15, 900 5 ........ 16,500 

28 ........ 11, 600 6 ........ 12, 200 

29 ........ 9,000 7 .... · .... 10,400 

30 ........ 15,400 8 ........ 9, 200 

31. ....... 40,600 9 ........ 10, 100 

Apr. 1 ........ 18, 100 10 ........ 11, 700 

2 ........ 13, 500 11 ........ 13, 100 

3 ......... 11, 700 12 ........ 18,000 

4 ........ 9, 100 13 ........ 11, 700 

5 ........ 8, 600 14 ........ 8, 700 

6 ........ 8, 300 15 ........ 8,800 

7 ........ 8, 350 16 ........ 14, 100 

8 ........ 8, 700 17 ........ 9,450 

9. ······· 8, 700 18 ........ 7, 200 

10 ........ 8, 600 19 ........ 11, 700 

11 ........ 8,000 20 ........ 10,300 

12 ........ 7, 700 21. .. •.• ~ .. 8,400 

13 ........ 7, 950 22 ........ 8,200 

14 ........ 7,500 23 ........ 8, 100 

15 ........ 8,100 24 ........ 6, 100 

16 ........ 8, 100 25 ........ 6,000 

17 ........ 8,500 26 ........ 5, 700 

18 ........ 8,500 

19 ........ 8, 900 July 2 ........ 6,000 

20 ........ 9, 200 3 ......... 6, 600 

21. ....... 9, 200 4 ........ 6,000 

22 ........ 9,200 I 5 ......... 5,800 

a See U.S. Goo!. Survey Water-Supply Paper 213, pp. 142-143, 1907. 

The flood channel in the vicinity of the 

barrier is 800 to 1,500 feet wide and is floored 

by gravel. Through the floor run n1inor 

channels, and at most points one of the minor 

channels is deeper and broader than the others, 

so as to carry all the water at low stages. At 

low stages such movement of gravel as takes 

place is purely local, tending toward but never 

accomplishing the filling. of the deeper pools of 

the minor channel. As the . discharge increases and the water first spreads over the 

broad gravel plateau and then deepens on it, 

through transportation is substituted for local, 

.and the amount·of through transportation (of 

bed load) then increases rapidly with increase 

of dept~ and velocity. We are at present 

concerned with the relation of the amount of 

through transportation to the discharge, and 

for the discussion of this I assume (1) that 

through transportation begins when the discharge reaches 5,000 second-feet, and (2) that 

the amount of through transportation, or the 

bed load, varies with the 1.3 power of the excess of discharge above 5,000 second-feet. 

The first of these assumptions is arbitrary; the 

second is founded on the discussion of laboratory data. 1 The result of a computation on 

this basis is that the bed load for the entire 

season from the autumnal low stage of 1905 to 

that of 1906 was proportioned to that of the 

flood of January,.1906, as 100 to 23. During 

all higher stages the bed load inciudes the 

grade classed as gravel in the an~lysis of the 

deposit above the barrier. 

Data for· the estimation of the suspended 

load also were ·acqUired at the Smartsville 

gaging station. During the year .1905 a sample 

of the water was collected daily at this station. 

The samples of 10 consecutive days were combined in a composited sample, and for each 

composite the solid contents were separated 

and weighed. By the combination of these 

determinations with the discharges of water 

for the same periods the total suspended load 

was computed. 

Table 12 gives the data for the first nine 

months of the year. As the river discharge 

varied greatly during some of the 10-day 

periods, and as the proportion of suspended 

matter was in general greater during high 

stages than during low stages, the computa1 Gilbert, G. K., The transportation of d6bris by running water: U.S. 

Geol. Survey Prof. Paper 86, 1914. 
56 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

tion of suspended load based on the composites 

does not give the same result that would have 

been obtained had the corresponding data for 

the individual days been used. Analysis of 

the record led to the conclusion that the tabulated total is much too small and should be 

increased about 20 per cent. On the basis of 

the same analysis, combined with the recorded 

'discharges for the closing months of 1905, an 

allowance was .made for the suspended load of 

those months-which fell outside the period of 

sampllng-and an estimate was thus completed for the year included between the dates 

of survey. 

TABLE 12 .-Suspended matter in Yuba River at Smartsville 

gaging station for 10-day periods in 1906. 

Observed Total load suspended Discharge suspended matter of water Month. (parts per (acre- matter 

million of feet). (cubic 

water). . yards). 

January ......... · ....... 80 10,000 910 

1, 700 360,000 693,200 

260 90,000 26,510 

February ............... 220 45,000 11,210 

300 97,500 33,130 

360 137,500 56,080 

March ................. 320 112,500 40,780 

350 192,500 76,330 

700 437,500 346,900 

April •.... -· ............ 260 205,000 60,390 

230 165,000 42,990 

350 152,500 60,460 

May ................... 290 242,500 79,680 

190 175,000 37,670 

240 250,000 67,970 

June ....... --:-. -. -· -· · 350 250,000 99,130 

230 227,500 59,190 

140 127,500 20,220 

July .................... 120 107,500 14,620 

160 65,000 11, 790 

270 37,500 11,480 

August ................ 90 18,000 1,830 

70 14,500 1,150 

85 14,500 1,400 

September ............. 45 10,000 510 

35 10,000 390 

35 9,700 380 

Uncorrected total 

for January to 

September, 

1906 ........... ................. ..................... 1,856,300 

Allowance for differ- ence between daily samples and 10-day composites ........... Estimate for October to ................. ..................... 371,300 

December, 1905 ...... .................. .................. 14,400 

Total suspended load for flood 

season, 1905-6 .. .................... ................... 2,242,000 

On a single day during the flood of January, 

1906, the suspended load was determined with 

much care at the Marysville carriage bridge, 

close to the mouth of Yuba River, and the 

details and result of this determination are 

shown in the following table: 

TABLE 13.-Suspended matter (parts per million) in sam- ples of water collected from Yuba River under D Street 

Bridge, Marysville, Jan. 19, 1906. 

[Collection and analysis by C. H. Stone.) 

Location. Depth.a Silt. Coarser Total. material.b 

Ft. in. 

South end of bridge. 11 1 606 309 615 

Do ............ 9 0 634 250 884 

Do ............ 5 0 614 150 764 

Do ............ 2 4 668 55 719 

Do ............ 3 626 . 28 654 

Near middle of br!dge~ .......... 10 0 798 225 1,023 

Do ............ 7 0 778 190 968 

Do ............ 4 0 782 202 984 

Do ............ 3 792 249 1,041 

Deepest part, near north shore ...... 14 0 614 377 991 

Do ............ 12· 0 626 147 773 

Do ............ 7 0 560 46 606 

Do ............ 4 4 464 35 599 

Do ............ 6 554 36 590 

Averages .... ................ 658.7 c 164.5 822.9 

a The lowest depth in each series was within 1 foot of the bottom. b The "coarser material" includes all particles exceeding in diameter 

0.0013 millimeter (0.00005 inch). c In the 164.5 parts of coarse material are included 8.1 parts of organic matter. 

The reported discharge of· the river on the 

day on which these determinations were made 

was 33,000 second-feet, and a rough computation based on the Marysville observations 

indicated an annual load of suspended matter 

only one-half as great as that derived.from the 

observations at the Smartsville gaging station. 

Little weight, however, should be given to the 

condition of the water on a single day, and the· 

discrepancy may be due wholly to unexplained 

irregularity. On the other hand, it may be 

due in part to the difference in velocity at the 

two stations. The current was much stronger 

in the Smartsville narrows than at Marysville, 

and the stronger current, by maintaining in 

suspension coarser detritus than was thus 

carried by the weaker, also carried a larger 

quantity. The Smartsville result better represents the conditions at the barrier, and the 

Marysville observations are placed on record 

chiefly as an illustration of the fact that the 
STUDIES ON THE LOWER YUBA. 57 

suspended load may be so impartially <;lis- The grouping as sil.t, sand, and gravel is that 

tributed through the body of the current as found convenient in classifying the deposits 

not to be grossly misrepresented by samples above the barrier. It. recognizes the readily 

taken at the surface. discriminated aggregates and is not analytic. 

The average content of three samples col- What is called sand is not a pure sand, but inlected at the surface is about 7 per cent less eludes in intimate mixture much :fine material 

than the average for all samples. It is note- that by itself would be classed as silt, and, 

worthy, moreover, that the variation with similarly, that which is called gravel has much 

depth is shown only in the distribution of the sand in its composition. A few samples of the 

coarser particles, not at all in that of the finer. "gravel" were·subjeoted to.mechanical analysis, 

During higher flood stages the suspended load and the results indicated that the :finer gravel 

at Snutrtsville narrows must have included contained about 45 per cent of sand and the 

1nuch sand, for the current there was violent, coarser 15 per cent. If the material of the 

but, in the absence of a mechanical analysis, I year's detrital load were separated into three 

regard it as improbable that a notable amount parts mutually exclusive as to size of grains, 

of this sand was caught in taking the samples. the proportions would be about 31 per cent 

If allowance were made for it the estimate of silt, 37 per cent sand, and 32 per cent gravel. 

suspended load would be somewhat increased. It is proper to inquire whether the moveWe are specially concerned, however, with the ment of detritus in the season of 1905-6 was 

evaluation of the load at the barrier, where, normal or exceptional. The data available for 

it is thought, most of the sand followed the the discussion of the question are the daily 

botton1, and the estimate as it stands n1ay be discharge records at the Smartsville station 

taken to represent the entire suspended load and the precipitation records at neighboring 

at that point as well as the silt factor of the mountain stations. The discharge records have 

suspended load at the narrows. The estimates . been practically continuous since 1903 and the 

contained in the following table take account I precipitation records at Colfax and Summit 

of the data discussed in the preceding para- since 1871. From the daily discharge the 

graphs and also of various niinor factors the relative capacity of the river for transportaInention of which seems unnecessary in view tion was computed for nine flood seasonsof the unavoidably large uncertainty of the October 1 to Septe~ber 30~and the capacity 

general result. in the season of measurement, 1905-6, was 

thereby compared with capacities in eight TABLE 14.-Material passing ove:r barrier No. 1,_ Yuba · h h 

Rive:r, between October, 1905, and October, 1906, ~n thou- other seasons. T en t e nine capacities were 

sands of cubic yards. plotted in relation to the corresponding prePeriod. Silt. Sand. Gravel. Total. 

During the flood of January, 1906 ............... 475 200 100 775 

Durmg the remainder of 

the year ............... 1, 715 1,430 1, 650. 4, 695 

2, 190 1, 630 1, 750 5,470 

The combination of Tables 12 and 14 gives 

the following estimate and classification of the 

detrital load of the river from October, 1905, 

to October, 1906: 

cipitations, a curve was drawn to express the 

law of relationship, and from this curve was 

inferred the capacity corresponding to normal 

precipitation. The discussion, the details of 

which are· omitted, assumed (1) that the 

river's capacity for ·transportation varies with 

the 1.3 power of the discharge less 5,000 cubio 

feet per second, (2) that the discharge of a 

season is in the long run proportional to the 

seasonal run-off of the river basin, and (3) 

that the run-off varies with the precipitation, 

but more rapidly; 1 and it resulted in the conclusion that the normal load of Yuba River is .Cubic yards. 

Silt ........... : .............................. 2, 200, ooo about four-tenths of the load in 1905-6, or 

Sand ............ : ........................... 1, 900, ooo 880,000 oubic yards of silt, 760,000 oubic yards 

Gravel. ..................................... 3, 100, 000 --------------------

1 See discussion by C. E. Grunsky in Am. Soc. Civil Eng. Trans., 

7, 200, 000 vol. 61, pp. 496-515, 1908. 
58 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

of sand, 1,240,000 cubic yards of gravel, a 

total of 2,880,000 cubic yards. 

The use of the phrase "normal load" in this 

connection requires qualification. It should 

be understood to mean the load that would 

have been carried by the Yuba at this point in 

the season of 1905-6 if the precipitation for 

the season had been normal in amount and 

distribution. The characterization would not 

apply to another point on the river, nor to this 

point a decade earlier or later. Tha supply of 

coarse debris from the mountains, as shown 

by the changes at the Smartsville gaging station (see p. 28), had been waning for about 

five years and its waning has continued. The 

supply of fine debris, which had begun to lessen 

20 years before, is probably still growing less, 

and its rate of change in 1905-6 may have been 

greater than that of the coarse debris. So 

the estimate given as normal for 1905-6 is 

below the local normal for a preceding period 

(not less than a decade) and above the normal 

for all later years. · 

RELATION OF THE YUBA'S LOAD TO OTHER 

ESTIMATES. 

As· already stated (p. 39), the estimate of 

the Yuba's load has been used in estimating 

the volume of mining debris remaining in the 

mountain portion of the Yuba River basin in 

1914. Of the normal load of the Yuba at barrier No. 1 in 1905-6 the chief part was mining 

debris. The volume ascribed to the nonmining debris for a period of 65 years (p. 46) 

indicates for the season 1905-6 a volume of 

600,000 cubic yards and leaves for the normal · 

annual load of mining debris at that date 

2,300,000 yards. This gives a point on a curve 

representing the variation of the rate of flow 

of mining debris from the· nwuntains by way 

of the Yuba. 

Other data affecting the curve are contained 

in the history of the development and restriction of hydraulic mining. The outflow increased with the increase of mining, and its 

rate of increase was, on the whole, more and 

more rapid until the restriction of mining, 

which began in 1884. The outflow of fine 

debris was then abruptly lessened, but the 

maximum discharge of coarser debris was not 

reached for several years. After the outflow 

of debris came to depend· chiefly on the wasting of the temporary deposits of the mountains the rate of outflow was a diminishing 

rate, a rate destined to become very small 

when the deposits shall be nearly exhausted. 

The total outflow from the mountains is equal 

to the total volume of mining tailings less the 

volume of tailings so placed as to constitute 

permanent deposits. To supplement these 

data, two assumptions were made-first, that 

the rate of outflow in 1956 will be one-tenth 

the rate in 1906 and, second, that the volume 

of tailings remaining in the mountains in ·1956 

will be 25,000,000 cubic yards, and a curve of 

the variation of rate of outflow was then drawn 

to fit the data and conditions. That curve 

yielded the following estimates: Mining debris 

still remaining in the mountain deposits of the 

Yuba River basin in 1914, 65,000,000 yards; 

mining debris to be removed from the mountains by Yuba River in the 50 years following 

1914, 42,000,000 yards. The first of these estimates has already been used in discussing the 

present distribution of the mining debris, and 

the second will be used in the consideration of 

its ultimate distribution. 

SCOURING BELOW THE BARRIER. 

A stream flowing over a detrital bed adjusts 

the general slope of its bed, making it as steep 

as is necessary for the transportation of its 

bed load and no steeper. The adjustment of 

slope to load is accomplished, paradoxically, by 

means of a local adjustment of load to slope. 

Wherever the slope is too gentle for the load 

a part of the load is dropped, and the grade is 

thereby built up. Wherever the slope is steep 

enough to carry more load than the stream 

brings to it the stream increases its load by 

scouring the bed, and the slope is thereby 

pared down. Before the erection· of the barrier tP.e Yuba channel at that point was adjusted to the transportation of the bed load 

brought from the mountains in time of flood. 1 

The barrier disturbed that adjustment by creating slack water and arresting the bottom 

load. The river passed from the crest of the 

barrier to the channel bed below without any 

load, but it could not flow without load on 

a slope of debris suited for the transportation 

of a large load. It therefore took up load and 

1 A few years earlier the piedmont deposit ceased to grow at this paint, 

and its degradation probably began a little before the building of the 

barrier. The adjustment of slope to load may therefore have been 

approximate only, but any defect of adjustment was so slight that the 

statement in the text is practically warranted. 
'i.J. s. GEOLOGlCAL SUitv·.t:Y N\OFl~SSJO:NAL PAPER 1.05 PLATi<:.: XXiil 

N 

D 

500 0 500 1,000 FEET 

MAP OF THE BED OF YUBA RIVER ABOVE AND BELOW BARRIER NO. 1, IN OCTOBER, 1905. 

By S. K. Baker. Contour interval2 feet. The same configuration of bed is shown in Plate XXI, A. 
U.S. GEOLOGICAL SUIWEY PROFESSIONAL PAPER 105 PLATE XXIV 

MAP OF THE BED OF YUBA RIVER ABOVE AND BELOW BARRIER NO. 1, IN OCTOBER, 1906. 

By C. J,. Nelson. Contour interval 2 feet. The same configuration of bed is shown in Plate XXII, B, and in Plate XXV, A and B. 
STUDIES ON THE LOWER YUBA. 59 

thereby scoured the old bed and reduced the 

slope. (See fig. 7.) The sc.ouring continued 

below the barrier as long as deposition cont.inued above it, and the rate o{ cutting below 

must have been ap'proximately equal to the 

rate of filling above during the whole history 

of the barrier. So, although the barrier probably arrested in its :first year one-half the bed 

load of the river and in its second year onefifth, there is no reason to ~uppose that it dinlinished the river's load a few miles downstream. 

It was in anticipation of this scour and to 

procure quantitative data concerning it that 

the survey of the river bed was extended half 

a mile below the barrier. 

Prior to the construction of the barrier the 

river bed at that point had a width of about 

1,500 feet and consisted of a platform of gravel, 

FJOUUE 7.-Dlagrammatic longitudinal section at barrier No. 1, Yuba 

JU ver, illustrating the relation between fill above the barrier and scour 

below it. 'l'ho straight line a-a represents the profile of tho ri vor bed 

before tho placing of tllc barrier. 'l'ho barrier was completed to the 

level marked 114" iu1904. Floods then made thodoposit.b and e:fl"eeted 

tho scour r.. 'rho upper part of the barrier, 5, was added in 1905. The 

next flood made the do posit c and other floods tho deposit d, and while 

those bodies were being added tho volumcjwas removed by scour. 

traversed near the left bank by a summer channel, 6 or 8 feet deep, in which the water level 

was only 3 or 4 feet below the level of the platform. The apron .of the dam was sunk into 

this platform so that its upper surface was at 

approximately the san1e level. 1 After the 

·c01npletion of the fu·st unit of the dam and 

after the basin thus created had been filled by 

debris brought down by the floods of one season the tract of channel im1nediately below the 

barrier showed evidence of n1oderate erosion. 

}.1.inor channels a few feet in depth traversed the platform on severaJ lines, and the 

main chmmel was probably deepened a few 

feet but without notable widening. The generul degradation of the river bed perhaps 

amounted to an average of 2 or 3 feet. (See 

Pl. XXI, A..) It was at this time that the 

fu·st contour map was made (Pl. XXIII). In 

• This description portailts to a period before tho locality was visited by 

tho author and is based on oral and published statements oft he engineers 

in charge of the work. Soc Am. Soc. Civil Eng. Proc., vol. 32, pl. 6, 1906. 

I 

th~ ensuing 12 months the second unit of the 

barrier was added, making its total height 14 

feet. The basin thereby created was filled by 

the detritus brought down by the season's flood, 

and the second map (Pl. XXIV) was then n1ade. 

A comparison of the maps shows that the floods 

of 1906 reduced the gravel platform through 

the greater part of its area, the average cut being 2.5 feet. It also greatly broadened and· 

deepened the inner channel, the excavation in 

that region amounting to an average of 9 feet. 

The deepest line of channel in 1906 was on the 

average 19.5 feet lower than the deepest line in 

1905. The appearance of the bed· after these 

changes is shown by photographs reproduced 

as Plates XXV, A and B, and XXII, B. 

The area of the river bed surveyed below the 

barrier was ~bout one-third as large as the 

area above the barrier in which the surveys 

showed deposition to have taken place. From 

the former area 532,000 cubic yards were removed. If the area. of deposit~on is divided 

into three tracts, each approximately equivalent to that below the barrier, the volume deposited on the lower tract was 883,000 cubic 

yards; on the middle tract, 545,000 cubic yards; 

on the upper tract, 261,000 cubic·yards. 

When the water of a stream falling from a 

ledge plunges down onto a bed occupied by 

detritus, it produces and maintains at the foot 

of the cataract a deep hollow occupied by a pool, 

and the thalweg rises in leading from this pool 

to the channel beyond. If there was any tendency of the water that passed over the barrier 

to produce a pool of this sort it was successfully combated by the quarry rock inserted 

as a riprap at the toe of the dam, and the result of the excavation was a general profile 

with continuous descent downstream from the 

edge· of the. barrier. This feature of descent, 

as well as the fact that the reduction of surface below the dam included the whole width 

of the river bed, leaves no reasonable doubt 

that the reduction was caused by the application to the riyer bed of a flood discharge that 

was free or nearly free from bottom load and 

therefore competent to excavate the loose material over which it .passed. 

The ·great depth to which excavation below 

the barrier was carried suggests that the 

eventual breaching of the structure may have 

been due to the eddy reaction called tail erosion 

rat?er than to the erosion and piercin~ of the 
60 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

concrete facing. During the earlier part of the 

great flood of March, 1907, the channel beiow 

the barrier may have been excavated still 

deeper, enabling the tail erosion to overpower 

the protecting riprap and undermine the system of piles and cables constituting the framework of the barrier. On the other hand, it is 

possible that the gradually increasing stream 

of detritus pouring over the barrier checked the 

excavation on the downstream side and. determined a change from cutting to filling. However that may be, it is abundantly evident that 

a dam founded on a river bed of movable material will promote erosion on the downstream 

side in the same measure that it promotes 

depos~tion on the upstream side, and that such 

erosion is a factor to be reckoned with by the 

engineer. . 

The principle has various. other applications 

and may be employed where· erosion on the 

downstream side is a result to be sought as well 

as where its consequences are undesirable. 

SEEPAGE. 

In the autumn of 1905, after the basin 

created by the first unit of the barrier had been 

filled by detritus, and again in the autumn of 

1906, after the filling of the basin created by 

the second unit, seepage water was observed 

under the toe of the dam. In 1905, when the 

seepage was delivered all along the toe of the 

dam at levels from 10 to 13 feet lower than the 

water surface above the dam, the discharge was 

measured and found to be 10 second-feet.· This 

water contained no suspended matter but, 

having filtered through the deposit, was clearer 

than the water of the surface stream. Its. 

freedom from detrital load showed that it was 

performing no work of erosion at the time of 

observation and that the deposit in the basin 

above, although it had not completely sealed 

the basin, had so retarded and regulated the 

flow of underground water that the movement 

of such water did not endanger the dam. 

REMODELING OF CHANNEL. 

The maps prepared for the purpose of studying the influence of the dam included a river 

tract about 5 miles long, but less than half of this 

tract was actually influenced by the obstruction in the year that elapsed between surveys. 

Nevertheless the whole tract was rei,D.odeled by 

the river. The flood channel in this portion 

of the Yuba is definitely limited by permanent 

walls, and its bed is a floor of gravel from 500 

to 1,500 feet wide. This floor is traversecl by 

one or more minor channels, which for half the 

year carry all the water and which are much 

more than sufficient for the flow of late summer 

and autumn. The remodeling of the bed of 

the flood channel included a rearrangement of 

the minor channels, and its scope is fairly illustrated· by comparing the minor channels of 

1906 with those of 1905. Similar rearrangement occurred in other seasons, as is shown by 

extending the comparison to the Debris Commission map of 1898 and to a map made by the 

Geological Survey in 1908. The channel outlines of the four maps are assembled in figure 8, 

but the reproductions include only that part 

of the river between the narro~s and Parks 

Bar Bridge; a part not affected by the artificial 

changes at the barrier. 

The species of channel shifting thus illustrated appears not to belong to either of the 

two types to which the attention of the physical 

geographer has been directed, although it is 

covered by the experience of the hydraulic 

engineer. In the shifting associated with 

meanders the main channel of the stream is 

affected. Its position is gradually changed by 

the eating back of one bank and the building out 

of the other, and the whole series of changes constitutes an orderly, predictable development or 

evolution. The shifting associated with a system of anastomosing or "braided" channels is 

conditioned by rapid deposition, whereby a delta 

or alluvial fan is built up. A channel is clogged 

by a local deposit that acts as a dam, causing 

part of the water to overtop the channel wall, 

and the overflow excavates a new channel. 

The distribution of detritus over the plain is 

thus accomplished by the frequent diversion 

of the streams of the plexus, and the deposition 

of detritus is the occasion of the diversion. In 

the Yuba near Parks Bar Bridge the main or 

flood channel is not shifted, its position being 

fixed by the walls of the valley, but the minor 

or low-water channels, which are features of 

the bottom of the main channel, shift from 

season to season. The changes take place 

during floods and their results are revealed at 

low stages. 

The explanation I suggest is that the system 

of component currents within the flood torrent, 

as well as the associated syst.em of diverse 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXV 

A. DOWNSTREAM FACE OF THE COMPLETED BARRIER AFTER THE PASSAGE OF FLOODS 

THAT FILLED THE RESERVOIR WITH DEBRIS. 

Photographed September 19, 1906. 

B. A NEARER VIEW. 

The lowest of the three benches of the structure is the concrete apron. (See Pl. XXI.) The river bed was originally 

at this level, and its lowered position was caused by erosion. The angular stones seen at the left were placed 

below the apron after the erosion which followed the completion of the first unit, as riprap to protect against scour and l?ack lash. A heavier body of riprap was being placed at the date of this view, and some of it appears at 

the nght. 

EROSION BELOW BARRIER NO. 1, YUBA RIVER, RESULTING FROM DEPOSITION ABOVE THE 

BARRIER. 
STUDIES ON THE LOWER YUBA. 61 

velocities, varies with the magnitude of the 

flood. Each particular discharge, conditioned 

in its action by the fixed resistance of the outer 

banks, tends to develop a particular configuration of the bottom and if continued long 

0 Yz ZMIL~S 

]?lQum~ 8.-Position and form of tho low-wator channel of Yuba River 

from Smartsvillo no.rrowl? to Po.rks Bar Bridge in different yoars. 

'l'ho outor lines show tho high banks limiting the flood channel. Tho 

shirtings of tho debris bod which modified tho low-water channel 

woro ofYoctod by tho flood currents. 

enough will establish that configuration. As a 

flood waxes and wanes, or perhaps oscillates in 

height, there is a sequence of such influences, 

and this sequence has individual characteristics 

with each flood. The resulting configuration, 

uncovered at the end of the flood, is thus a 

function of a complex of conditions, and the 

configurations wrought by different floods reflect in their diversity the diversity of the flood 

histories. 

DAGUERRE POINT DAM AND TRAINING WALLS. 

The general project adopted by the Cali .. 

fornia Debris Commission for the control of the 

mining debris in Yuba River included several 

structures besides barrier No. 1, and two 

groups of. structures have been successfully 

installed and are now effective. To under .. 

stand how and why they modify the regin1en 

of the river it is necessary to take accqunt of 

what may be called the natural history of the 

piedmont deposit, and the following para .. 

graphs attempt to outline that history. 

The channel of the river fron;t the mouth of 

its mountain canyon to its junction with, the 

Feather was originally of gentle slope and. 

moderate width. The ban~s were of resis~ant, 

material, so that the channel could not shift. 

The channel bed was mainly of gravel. The 

stream was able to transport gravel on a bed of 

gentle slope because the quantity of debris 

supplied to it was small. When hydraulic 

mining greatly increased the stream's load, the 

slope was automatically increased by building 

up the bed, the amount of filling being greatest 

at the mouth of the canyon. One effect of the 

upbuilding was to broaden the waterway. A 

flood plain was created, over which flood waters 

were spread and on which channels were continually shifted and otherwise modified. The 

broadening of the stream at time of flood tended 

to reduce its transporting power an~ made the 

slope required for transportation steeper than 

it would have been with a narrower channel. 

The first mining debris to arrive was fine silt; 

afterward came sand also, and later gravel. 

At each stage of the invasion deposition was 

selective, coarser material, lodging near the 

head of the piedmont deposit and finer material near its foot at the mouth of the river. 

At an early stage the. visible deposit was mud 

at the mouth and sand near the mountain 

canyon. At a later stage the visible materials. 

were sand below and gravel above. At· the 

head of the deposit the slope was suitable to 

transport the coarser debris there constituting 

the bed, but farther down the slope was adjusted to the transportation of finer material 

only. 
62 HYDRAULIC-MINING DEBRIS IN THE SIER.RA NEV AD~. 

At the culminating stage ·of the deposit its 

head lay within the mountain canyon, and the 

slope of the channel was there comparatively 

gentle, 5 or 6 feet to the mile; that slope sufficed for the transportation of coarse g;ravel because the channel was narrow. In the next 

few miles downstream the quality of the load 

.remained. nearly the same, but the bed grew 

·broader, and the slope, responding to the 

change in width, became steeper, a maximum 

of about 20 feet to the mile being reached. 

Farther down, although there was still for 

some miles an increase of width, the change in 

the material of the load became the controlling 

factor, and the slope diminished as the debris 

became finer. At the mouth of the river the 

surface of the deposit was sand and the forward 

slope of the bed was about 5 feet to the mile. 

Up to this epoch, which was reached some 

time between the years 1895 and 1900, the 

whole history of the deposit had been one of 

growth. The supply of debris from upstream, 

gradually lessening for many years, now became so small that further increase of the slope 

near the head of the deposit was not demanded by the river's load, and growth ceased 

there, although continuing farther down. 

Then, with further reduction of debris supply, 

erosion began at the head of the deposit, but 

there only. The coarse material eroded was 

deposited farther down and all the downstream parts of the deposit continued to grow. 

It was at this stage that the natural course 

of events was interrupted by permanent artificial constructions. The natural course would 

have been substantially as follows: The erosion at the head of the deposit would affect 

the entire width of the deposit within the 

canyon, but outside of the canyon a trench 

would be made. This trench would afterward 

be deepened and broadened. It wou]d be extended downstream slowly and would not approach the mouth of the river for a number of 

years. Meantime the gravel eroded from the 

trench would be joined to the debris from the 

mountains and would help to build up the 

lower slopes of the piedmont deposit, and the 

plain of sand near the mouth of the river would 

be gradually converted to a plain of gravel. 

Eventually this plain also would be trenched 

and the flood plane of the river permanently 

lowered, but for several years, and perhaps for 

many years, the flood plane at the mouth would 

continue to rise, with attendant injury to the 

city of Marysville and neighboring districts. 

In the development of the trench through the 

deposit there .would be much lateral erosion, 

and the ultimate result would be a valley bordered by terraces of gravel. The original slope 

of the channel bed would be approached, but 

not reached, because the river's load of debris 

will not again be so small as before the advent 

of the whites. 

Daguerre Point (see fig. 6) is 4.5 miles below 

barrier No. 1 and about 10 miles above the 

mouth of the river. The general width of the 

debris plain near the point is 8,000 to 9,000 

feet. At the point it is 1 mile. The point is a 

small hill connected with the low upland north 

of the plain by a narrow neck. An artificial 

channel has been excavated through this neck, 

and·_ the floor of the channel, which is not of 

strong material, has been protected by a sill or 

low dam of concrete. To turn the stream to 

this channel a barrier or embankment has been 

built from the hill of Daguerre Point to the 

south edge of the gravel plain. In order to connect with a suitable upland, it has been run 

upstream as well as across the plain. The 

southeast end rests against H~llett Po.int, about 

1.8 miles from Daguerre Point. The crest of 

the concrete sill at the cut is a few feet above the 

level of neighboring parts of the gravel plain. 

These works were completed in 1910, so that 

the flood water~ of the following season flowed 

through the cut and had their level determined 

by the sill. An immediate effect was the filling 

of the shallow basin above the sill with debris, 

and after that the cut became a thoroughfare 

for the transportation of the river's load of 

debris. A permanent effect is the limitation of 

the possible degradation of the gravel deposit 

above Daguerre Point. A large body of debris 

will be rer;noved by the river before the ultimate profile of the river bed is attained, but 

another large body will be permanently stored 

below the plane of that profile. 

Closely associated with these works are two 

training walls, which extend down the debris 

plain from the sides of the Daguerre cut for a 

distance of about 2 miles and confine the river 

to a channel width of 2,000 feet. An effect of 

the confinement is to increase the efficiency of 

the current for the transportation of debris 

and enable the river to carry its load on a 

lower slope than would otherwise be necessary. 
STUDIES ON THE LOWER YUBA. 63 

In combination with the reduction of debris 

load that followed the establishn1ent of the 

sill, it has induced erosion of the channel bed 

below Daguerre Point and has restrained the 

normal tendency toward. continued building 

up of the deposit in the neighborhood of the 

river mouth. The deposit. near the mouth 

reached and passed its maximunl phase earlier 

than it would otherwise be reached, and the 

maximum was less high. The -training walls 

also protect considerable areas of the debris 

deposit outside then1 fron1 attack by the current, and these portions of the deposit are 

probably to be regarded as pern1anently :fi~ed. 

Before the establishment of the Daguerre 

barrier and the training walls the coarsest 

material of the debris plain near the river 

mouth was coarse sand. Soon afterward, and 

as a direct consequence of those works, gravel 

was carried along the. main channel to the 

river mouth. 

The hydraulic principle most emphatically 

illustrated b:y these results is that the efficiency 

of a cm·rent may be increased by confining it 

laterally, so as to make the ratio of the depth 

to width greater than it is under natural conditions on an alluvial plain; and it is thus 

possible to make a stream carry its debris load 

on a gentler slope than would naturally be 

assumed. 

An iinportant factor in the construction of 

the Daguerre Point works was the gold-mining 

dredge. That engine, advancing across a 

debris plain, digs a deep, wide trench and 

immediately fills it again with the same material. The digging takes place at the front of 

the dredge and the chief filling at the rear. 

The open trench between contains a pool of 

water on which the dredge floats. Within the 

dredge the debris is separated by a screen into 

coarse and fme. The fine, after treatment ,for 

the extraction of gold, is discharged into the 

pool. The coarse is discharged at the rear. 

As a result of this handling the site of the trench 

comes to be occupied by two distinct deposits, 

of which the upper is gravel without any admi..··dm·e of clay or sand. The rmnoval of the 

71139°-17-5 

clay, san_d, al}d very fine graVE1l which had 

previously occupied the interstices between 

pebbles of the coarser gravel does not greatly 

reduce the volume of that graV(3l, and consequently the total volume of the two pew formations is greater than the volmne of the same 

material as naturally con1bined, the increase 

of volume being ne~rly equal to the volume of 

the underlying finer formation. . The course 

of the dr~dg_e· is therefore-marked -by a ridge of 

·gravel, and this ridge may rise 10, 20, or even 

30 feet above the plain. 

Before the completion of the Daguerre Point 

works gold dredges had been introduced on the 

debris plain of the Yuba; and their work was 

so directed as to construct the Daguerre embankment as a by-product of gold mining. 

That embankment, instead of being a single 

ridge, is a plateau of gravel. It is not inlpervious,. but the water seeping through it does 

not affect its stability, and it is adequate for 

its purpose of turning the flood waters to the 

Daguerre cut. 

The training walls also are embankments 

made by the gold . dredges, after a futile 

attempt to construe'£ . them of the sand and 

fine gravel which there constitute the surface 

material. . .The chief' source of gold in this 

vicinity is an ancient coarse gravel underlying 

the recently deposited tailinga fron1 hydraulic 

n1ining. By working a gold dredge along the 

line selected for a training wall the positions 

of the two formations were practically reversed,· 

and the bouldery gravel which was lifted to 

the surface and constitutes the training wall is 

·said to succeed in resisting the attack of flood 

currents. Some of its finer components were 

washed away at :first, but there remains a 

facing of boulders which is adequate for the 

purpose. 

The preceding paragraphs were written in 

1914. In the following year the sill at Daguerre Point was raised 1.5 feet, the training 

walls below the cut were extended, and other 

training walls were constructed above the 

cut, thus increasing the protection against 

erosion. 
CHAPTER VIII.-LOOKING FORWARD. 

RIVER D£BRIS FROM SOURCES OTHER THAN works to restrain debris on Yuba River and to 

MINING.. control flood waters of Sacramento and Feather 

In considering t~e future movements of nvers. 

water-borne debris. in this region and their RESTRAINT OF D£BRIS ON THE YUBA. 

results, it is necessary to take account of the 

non-mining as well as the mining portion. The existing works on the Yuba-the DaThe non-mining waste assumed importance guerre Point barrier and spillway and the 

at the same time with the mining waste. associated training walls-are described on 

Its annual volume in the entire Sacramento- page 62. If no further measures are taken 

San Joaquin valley is now nearly_ as great as to restrain the river the slope of its bed 

that of the mining waste, and its origin is con- will gradually be reduced both above and below 

nected ·with so many and so vital industries the spillway, until a stable slope of about·5 feet 

that restriction is impracticable. Agricul- to the mile is reached. The channel bed at 

· ture and the use of roads are increasing and the mouth will be lowered, along with that of . 

. will continue to increase. The soil waste oc- Feather River, until the ante-mining level is 

casioned by them and by grazing is not likely approached or possibly reached. Along with 

to diminish, although the effect of expanding the lowering there will be broadening of the 

industries may in time be largely offset by the river's trench, and the broadening will be careffect of improved methods. Although we ried in many places to the slopes of the antecan not now make a direct comparison between , mining valley. The excavation will remove a 

·the soil waste under natural conditions and the large part of the piedmont deposit, but there 

soil waste as stimulated by non-mining indus- will remain, first, the basal portion protected by 

tries, we may feel confident that the contrast the Daguerre Point sill; second, the portions 

is strong and that the streams, quite inde- lying north and south of the training walls; and, 

pendently of mining ·conditions, are perma- third, a system of lateral remnants, constituting · 

nently charged with the transportation of terraces on the sides of the reopened valley. I 

loads greatly exceeding those furnished by estimate the quantity of debris which may thus 

purely natural agencies. be removed at 190,000,000 cubic yards, and the 

The additions to the debris output made by quantity fully protected by existing works at 

industries other than mining consist largely of 140,000,000 cubic yards. 

soil waste, which is dominantly of fine grain. There is good reason, however, to believe that 

The mining debris likewise contributes more the river will not be permitted to accomplish . 

to the suspended load of streams than to the this excavation without int~rference. By 

bed load, but its proportion of fine material is ~hange in the river's work from deposition to 

less than that of the soil.waste. Much of the excavation the problem of river control is sim-· 

finer material from mining went immediately plified, for a tendency toward automatic in-

. to the bays and inundated lands, and that trenchment will cooperate with any works that 

which rested by the way and is still in transit may be erected to limit its wandering. All of 

is dominantly coarse. As the stores of mining the debris plain below Daguerre Point which 

debris are gradually depleted the supply of has not been traversed by gold dredges is availcoarse debris to the Sierra rivers will dimin- able for agriculture if it can be protected from 

ish, but there will be less change in the supply the ravages of the river, and its agricultural 

of fine debris. value constitutes an incentive for the erection of 

In considering the future movements of levees or other protective works. Above Dadebris it is necessary to take account also of guerre Point the debris plain is less available for 

plans which have been adopted for engineering agri~ulture, but the deposits beneath the plain 

64 
LOOKING FORWARD. 65 

are more available for gold dredging, and the 

operations of the dredge may be depended on to 

obstruct and restrict the river's work of excavation. It is not improbable that the dredging 

work will be so conducted as to practically fix 

the river channel by training walls of "Qoulders. 

Finally, to the incentive of private interests is. 

to be added the cooperative and regulative 

work of the California Debris Commission, 

which represents the interests of the general 

public. 

Should engineering works restrict the river to 

a channel width of 2,000 feet the body of debris 

excavated from the Piedmont deposit will be 

only about 110,000,000 cubic yards instead of 

190,000,000. The actual quantity to be swept 

into Feather River will probably fall between 

these limits. 

FLOOD CONTROL IN THE SACRAMENTO 

VALLEY. 

The' area of periodically inundated lands in 

the Sacramento Valley is large. In 1894 the 

part directly associated with Sacramento River 

was estimated by Manson and Grunsky 1 at 

1,254 square miles. 'In the reclamation of this 

land for agriculture one tract after another is 

surrounded by levees, and the natural facilities 

for the storage of flood waters are thus restricted. In consequence of the restriction the 

flood levels are raised, and lands are inundated 

that had· previously not been covered. With 

the progress of reclamation up to the present 

time the total extent of inundation has not 

been greatly reduced, because the· areas· newly 

invaded by the water have been nearly as large 

as the areas from which the water has been 

excluded. The raising of the. flood plane had 

the effect also of making the levees constructed 

earlier, too low, and it became evident that it 

would be impossible to reclairp. the entire area 

unless provision was made for the freer escape 

of the flood water. To accomplish this a comprehensive plan would have to be adopted, and 

to this plan all future levee construction would 

have to be conformed. The subject was investigated by several boards of engineers, and 

a number of plans were formulated. The plan 

finally adopted by the State, in 1911, was that 

recom1nended by the California Debris ComJnission, and it included most of the features of 

1 California Comm. Pub. Works Ropt., 1894, p. 28. 

a plan proposed by Marsden Manson and C.~· 

Grunskv in 1894.2 Under this plan the State, 

through a special board, regulates the construction of private levees, and the United 

States, through the Debris Commission, executes all public engineering work; the cost of 

the public work is divided between the State 

and the Government. In the following outline the plan is developed only so far as is 

necessary to show its ·relations to the movement of debris. 

Along those portions of Sacramento River 

that are bordered by lateral basins the channels 

are to be straightened in places but not so enlarged as to carry the entire flood discharge. 

The excess of flood discharge above the capacity 

of the channel is to be conveyed by wide 

accessory channels called by-passes. The first 

by-pass will be east of the permanent channel 

and will traverse Butte and Sutter basins. 

Weirs will be so arranged in the bank of the 

permanent channel that water will escape to 

the by-pass only during floods. At the south 

end of Sutter Basin the diverted water will be 

returned to the permanent channel and immediately rediverted on the opposite side, entering there a second by-pass to be separated by 

levees from Yolo Basin. At the south end of 

that basin the water will again be returned to 

the main channel. Along Feather River the 

same object will be attained by limiting flood 

waters to a belt wider than the channel proper 

but including that channel. From the south 

end of Yolo Basin to the mouth of Sacramento 

River the river channel will be enlarged so as 

to carry the entire flood discharge. These 

elements of the plan are shown in figure 9. 

The minor drainage now received by the lateral 

basins from both sides of the valley will be 

intercepted by suitable canals and gui~ed to 

the by-passes, but the designs for these canals 

have not yet been prepared. 

The execution of the plan will require anumber of years. An immediate effect of its adoption was to stimulate the work of reclamation 

by landowners, and large additions to the leveed 

area are being made. The first of the public 

works to be undertaken, the enlargement of 

the lower river, has been begun. In the future 

conduct of operations some details of the plan 

2 The report of tho commission, which includes statements of other 

plans, is published as H. Doc. 81, ·62d Cong., 1st sess. 
66 HYDRAULIC-MINJNG DEBRIS IN THE SIERRA NEVADA. 

2 

Cl) 

<( 

() Q) 

0 

r 

c 

(/) 

):> 

!?'--'._,._.,_._ ....... 9_. _ _.....,r .,-----''P MileS 

FIGURE 9.-0utline of the major levee system adopted for control of floods in Sacramento Valley. The full lines show levees; the broken lines show boundaries of the areas 

which will require protection because lying below the flood plane in neighboring river 

channels and by-passes. 

will doubtless be modified, but it is 

hardly to· be questioned that its 

main features will be realized. 

One of the consequences of the 

projected changes will be the exclusion of the river-borne debris from 

the lands now inundated. At the 

present time, as in pas·t times, a 

considerable fr~ction of the fine 

debris carrie.d by the flood waters 

is deposited on the inundated lands. 

The substitution of by-passes for 

flood basins is the substitution of 

channels for reservoirs. In these 

by-channels the velocities of flood 

waters will be sufficient to prevent 

permanent deposition. The routes 

of the intercepting carials have not 

yet been determined, but one of the 

prime conditions to be satisfied in 

their planning is that the canals 

have sufficient fall to prevent clogging by sediment. So they will not 

be receptacles of debris; and when 

the system shall have been completed all the fine debris will be 

carried to the bays. 

Another result of the projected 

changes will be the strengthening of 

the current in the main channels of 

the rivers. Except· in the immediate vicinity of the bay the flood 

plane will be raised and its slopes 

steepened, and these two changes, 

in combination, will quicken the 

flow in the channels. As a result 

of that quickening the transportation of bed load will be promoted 

and the channel beds will be scoured. 

The removal of the sand deposits 

caused by hydraulic mining, which 

has already commenced, will be 

accelerated. But for the enlarged 

output of non-mining waste the bed 

profiles of the rivers would eventually be reduced below their original 

positions, and it is not improbable 

that that result will be attained in 

a considerable portion of Sacramento River. The material thus 

scoured out will be carried to the 

bays. 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXVI 

A. MODE OF CONSTRUCTION. 

Logs placed transverse to the direction of the stream alternate with layers of branches placed with the butts down- stream, and a tangle of twigs helps to arrest the debris. The initial dam is low, and as debris accumulates 

against it additions are made. Photographed in May, 1908. 

After the filling of such a dam by debris a breach eventually occurs, unless the entire stream has been diverted 

to another course. The removal of the debris then begins and nearly all of it finally escapes. Photographed 

in 1905. 

I 

BRUSH AND LOG DAMS FOR STORAGE OF HYDRAULIC MINING DEBRIS. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXVII 

A. NOVEMBER 3, 1905. 

First construction in 1901; height increased 10 feet in 1903. The crib work was filled with gravel, except a surface . facing of quarry rock. 

B. OCTOBER 27, 1908. 

The dam had failed in 1907, four years after its completion. With better filling it might have lasted until the 

timbers began to decay, but its storage of debris was in any case temporary. 

CRIB DAM FOR STORAGE OF HYDRAULIC MINI TG DEBRIS. 
LOOKING FORWARD. 67 

The reclmnation of extensive inundated lands 

bordering San Joaquin River is also in ·progress, 

and its effect on the movement of debris will be 

the same-the delivery of the ·entire output to 

the bays. 

MINING D£BRIS NOW STORED IN THE MOUNTArN AND PIEDMONT DEPOSITS. 

The deposits on the hydraulic dumps and in 

the valleys of upland creeks have been estiInated at 265,000,000 cubic yards. The annual 

wasting of these has decreased in the past and 

will continue to decrease. The piedmont deposits have been estimated . at 520,000,000 

yards, and the annual wasting of these is perhaps not yet decreasing. The wasting of the 

Yuba deposit has barely begun, and the augmentation of its rate probably offsets the reduction in rate at other localities. After the lapse 

of, say, 50 years the annual tribute to the 

streams from both classes of deposits will have 

become so small that what then remains may 

be regarded as permanent. Guided chiefly by 

observations on the Yuba, I estimate the pernlanent·deposits in the mountains at 100,000,000 

yards and the permanent piedmont deposits at 

335,000,000 yards. These estimates are necessarily arbitrm·y and rough. They leave as an 

estimate of total future waste from existing 

mountain and piedmont deposits· 350,000,000 

cubic yards. 

In making these and other esti1nates of the 

volun1e of hydraulic tailings temporarily or 

permanently lodged in the mountains I have 

included, without specific mention, the tailings 

arrested by restraining dams constructed under 

permits issued by the California Debris ComInission. In the early years of the commission's 

control its requirements were satisfied by dams 

of brush or of wooden cribs loaded with stone 

or gravel, and it is only in recent years that 

concrete dams have been prescribed .. In a few 

projects separate spillways were provided for 

the streams on which brush and crib dams were 

built, but usually the streams were allowed to 

cross the crests of the dams, and in all such 

places the storage was not permanent. After 

the wood of brush and cribs has decayed, and 

often sooner, the dams are breached and the 

stored debris is exposed to wash. (See Pis. 

L~VI and L~VII.) 

In considering what part of the mining debris 

now on the dumps should be regarded as permanently ·lodged and what part as merely delayed in transit, accoun:t was. taken also of 

waste from the steep and bare walls of old 

hydraulic mines. (See p. 50.) 

FUTURE DISTRIBUTION OF D~BRIS. 

From this time onward the valley rivers are 

not accumulators of debris, but the deposits 

they have previously acquired are to be gradu .. 

ally removed. Their work as carriers, always 

their chief work, will then remain. Their load, 

destined to diminish for some decades, will then 

have become practically constant but will be 

much larger than it was before the settlement 

of the country. Having formerly amounted, 

perhaps, to 2,000,000 yards annually, it will 

have a future average of not less than 8,000,000 

yards. Assuming that a period of 50 years will 

close, for the rivers, the history of the hydraulic 

mining debris of the last century, we may now 

estimate for that period the rivers' entire work 

of transportation. From the debris deposits 

of the mountains and the piedmont they are 

to receive 350,000,000 cubic yards; from their 

own beds they will excavate 100,000,000 yards; 

and the soil waste brought to them will add 

about 400,000,000 yards, giving a grand total 

of 850,000,000 yards of debris. 

Of the material to be contributed from 

mountain and piedmont deposits two-thirds is 

coarser than silt; the deposits now in the river 

charu1els are almost wholly of sand; of the soil 

waste seven-eighths is silt. Of the grand total 

475,000,000 cubic yards may be classed as silt 

and 375,000,000 yards as sand and gravel, 

c4iefly sand. 

The inw1dated lands, from which the floods 

will be gradually excluded, probably during 

the first half or first third of the 50-year 

period, may be assumed to receive 10 per 

cent of the silt, or 50,000,000 yards. The 

remaining 425,000,000 yards will be delivered 

to the bays, and part of it will pass from the . 

bays to the ocean. The coarser debris also 

will be delivered to the bays, but not in its 

present condition, for it will have been worn 

down in its long journey. Much of the sand 

will reach the bays as silt, and much of the 

. gravel as silt and sand. It is possible that 

none of the gravel now in transit will reach 

the bays as gravel, but it may be assumed that 

as the pre-mining slopes of the 'river channel 

are approached the character of the pre-mining 
68 . HYDRAULIC-MINING . DEBRIS IN THE SIERRA: NEVADA. 

channel bed will also be approached. In a 

general way the mining debris now journeying 

along the beds of the valley rivers is of finer 

grain than the debris it overlies, and when 

that older and coarser debris ·shall again be 

exposed to the current the conditions may be 

suitable for its transportation. The conditions 

will not be the same as in the earlier period 

because the load of soil waste will be greater 

and because the flood discharge following the 

channels will be greater. 

From the character of the channel deposit 

in San Pablo Bay (see p. 92) it is inferred 

that nearly the whole of the debris delivered 

to the bays, 800,000,000 cubic yards, will have 

been so comminuted before ~t comes to rest 

that it should not be classed as sand. The 

greater part of this rna terial will be . retained 

on the shoals of the bays, and a minor part, 

arbitrarily estimated at 40,000,000 cubic yards, 

will reach the ocean. 

In completing a series of estimates in which 

personal judgment plays so important a part, 

I wish to repeat that my excuse for presenting 

them lies in the leaven of definite measurement 

they contain. The measurements of mining 

excavations in .the Yuba River basin help to 

gage the largest body of debris at its source. 

The measurements of changes in the bays help 

to gage the transported debris at its chief 

point of deposition. · The measurement of the 

Yuba's detrital load for a single season aids 

judgment as to rates of transportation. There 

is further aid in measurements of the greatest 

of the piedmont deposits and in numerous eye 

estimates by myself and others. In the use 

of the imagination by which these quantitative 

elements have been supplemented the attempt 

has been made to utilize all available laws of 

interdependence so as to organize the estimates 

into a consistent system. · 

Of the injurious effects of the mining debris 

only two have future importance, provided 

hydraulic mining continues to be regulated as 

at present. 'fP.e encroachment of the debris 

on agricultural lands has ceased, and future 

developments in the areas of the piedmont 

deposits will be in the direction of their return 

to agricultural service. The influence of the 

debris on valley floods is steadily diminishing, 

is now less than the influence of the reclamation of lowlands by levee building, and. in a 

few years will be so overshadowed by the 

greater results of reclamation as to be· properly r~garded as negligible. The conditions for 

navigation in the rivers are steadily improving 

and will soon equal those which existed before 

the debris invasion. But deposition in the 

bays will continue, with increasing obstruction 

to navigation and additional encroachment on 

the tidal prism. 
CHA~TER IX.-RELATIONS OF DEBRIS MOVEMENT TO THE ~OLDEN GATE BAR. 

PROCESSES AND CONDITIONS. 

The depth of water on the bar outside the 

Golden Gate is a matter of prime importance 

to the port of San Francisco. That depth is 

believed to depend chiefly on two factors-the 

supply of sand brought to the bar and the velocity of the tidal cui·rents by which it is distributed. Tluough these factors it may be 

affected by the flow of mining debris, by the 

increase of soil waste incident to the development of agriculture and other rural industrie~, 

and by the reclamation of marsh lands. It 1s 

proposed in the present chapter to ~scus.s these 

influences and in order to do so Intelligently ' . it, is necessary to understand, at least 1n a 

general way, the natural processes 'by which t~e 

bar has been shaped and by which its form 1s 

maintained. 

The bar is composed of sand. The sand has 

three sources-cliffs of the outer coast, cliffs 

of the inner coast, and streams tributary to 

the bays. · 

For 7 miles north of the Golden Gate the 

coast presents a series of cliffs, and it is evident 

that these are sapped and eaten back by the 

beating of the waves. The coarser waste fro~ 

that erosion is drifted by shifting currents 1n 

two directions. Part of it reaches Bolinas 

Lagoon where it is built into a bar across the 

entranc~, and another part goes past Point 

Bonita to the entrance of the Golden Gate. 

Thirteen miles south of the Gate, at San Pedro 

Point beoins another line of cliffs from which ' b the waste is swept in two directions. The 

larger part goes northward, is reinforced by 

other waste at and near Mussel Rock, and 

maintains the great beach (Ocean Beach) south · 

of Point Lobos. A portion of its sand escapes 

from the sea and is blown inland, where it 

travels in dunes; another portion finds its way, 

either directly or indirectly, to the Golden 

Gate bar. Some of these geographic relations 

are shown in figure 15; they are more fully 

shown on United States Coast and Geodetic 

Survey chart 5500. 

The mode of pr~gression of the cliff-born 

sand involves the cooperation of waves and 

currents. Each wave disturbs the sand of the 

beach momentarily lifting a portion, and while 

the g;ains are free from the bottom they drift 

with the current. Even a gentle current thus 

determines the direction of sand movement. 

On this part of the coast the normal direction 

of the shore current is northward. There is a 

slow northward drift known as the Davidson 

inshore eddy/ and this determines the dominant movement of sand; but strong northwest 

winds may temporarily reverse the current and 

sweep the sand · in the opposite direction. 

The travel of sand is not confined to the 

immediate vicinity of the beach but may be 

induced by storm waves at considerable 

depths, and there can be no question that the 

crest of the ·bar is well within the range of 

such action, for large storm waves break in 

passing the bar, ~nd the reaction of the bottom 

on the waves is the counterpart and index of 

the reaction of the waves on the bottom. 

The shores of the strait and of the bays are 

washed by waves, and though the attack is 

less vigorous than 0~ the outer coast it caus~s 

erosion and creates cliffs. Part of the debns 

from this erosion finds its way as sand to the 

channels and is swept to and fro by tidal 

currents, with a net movement toward the bar. 

The debris brought to the bays by rivers and 

creeks consists in part of .sand and is carried 

forward in the same manner by the tidal 

currents. 

In the map of the bar and strait (fig. 10) 

the configuration of the bottom is shown by 

contours with equal intervals of 10 fathoms. 

The headlands at the entrance to the strait; 

Point Bonita and Point Lobos, are separated 

by a space of 2.3 miles, but the bar has a 

length of about 13 miles, swinging seaward in 

a ·great arc. It is not closely united to the 

shore at either end, but is separated by chan1 u.S. Coast Pilot: Pacific coast; California, Oregon, and Washington, 

2d ed., p. 11, 1909; Coast Pilot of California, Oregon, and Washington, 

4th ed., p. 227, 1889. 

69 

• 
70 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

nels. The bar is wholly submerged, its crest 

lying from · 5 to 6 fathoms· below low-water 

level except at the north, where it has a minimum submergence of about 4 fathoms. But 

for the tidal currents the bar would extend in 

a direct line from Point Lobo~ to Point Bonita, 

and its crest, a continuation of Ocean Beach, 

The magnitude of the bar is affected also by 

the supply of sand. As the sand of its surface is agitated by currents and by the passage 

of storm waves, the grains are struck and 

rubbed against one another and are thereby 

broken and worn. The wearing process is 

slow, but its result is to reduce the grains until 

FIGURE 10.-Configuration of the bottom in the Golden Gate and on the Golden Gate bar. Based on chart 5532 of the United States Coast and 

Geodetic Survey, with additional details from original plats of survey. Contour interval, 10 fathoms. The 6-fathom and 5-fathom curves are 

shown on and near the bar by dotted lines. The dates of survey were, for the bar, 1900; for the strait west of Fort Point, 1894-1897; east of Fort 

Point, 1871:..1873. 

would be above the level of high tide. Its they are so small as to be carried far away in 

great distance from the shore and its deep sub- suspension. If there were no fresh supply of 

mergence are due entirely to the speed and sand, the bar would waste away, and its magvolume of the ebb tides. Any modification nitude at any particular time represent~ a 

of the bays which has the effect of reducing resultant between supply and waste of sand. 

·the volume of the tides tends to cause the Any modification of natural conditions which 

crest of the bar to move landward and to rise has the effect of increasing the supply of sand 

nearer to the surface of the water. will cause the bar to grow and will bring its 
RELATIONS OF DEBP.JS MOVEMENT TO THE GOLDEN GATE BAR. 71 

crest nearer the water surface. Some of the 

statmnents in this paragraph and the one preceding it admit of qualification, but it has not 

seen1ed best to expand this preliminary outline 

of theoretic relations. The subject will be 

resruned near the end of the chapter. 

Where the strait is narrowest, in the vicinity 

of Fort Point, the tidal currents have their 

greatest velocity and maintain a very deep 

chmmel. There is one sounding of 63 fathoms; 

thence in both directions the channel shoals 

as it broadens. Outside the headlands the 

bm· incloses a funnel-shaped basin, deepenillg 

towm·d the strait, as shown in figure 30 (p. 140). 

When the tide rises. outside the bar, it tends 

to flow into the basin from all sides but is opposed in part by the momentum of the stillflowing ebb tide, which is directed westward. 

It results that for a time the currents set 

outwm·d across most of the bar but inward 

through Bonita and South channels. 1 During 

the period when.the ebb tide is strong its courses 

outside the str~it are much influenced by the 

m01nentmn acquired within the strait. It 

spreads to all parts of the bar, but its strongest 

set is toward the west and southwest. It does 

not send a strong current through South Channel, and it is said to create an eddy current 

southwestward in Bonita Channel. Thus in 

Bonita and South channels the principal currents are towm·d the entrance to the strait, 

while those away from the strait are feeble. 

It can hm·dly be questioned th~t all the sand 

which drifts southward from the cliffs north of 

Point Bonita is cm·ried by the flood-tide currents of Bonita Channel to the entrance of the 

Golden Gate and is then borne by the currents 

of ebb tide outward to the bar. South of the 

entrance the evidence is less clem·, but I regard 

it as probable that the chief route of the sand 

which has followed the coast from San Pedro 

Point and Mussel Rock is northward with the 

flood tide through South Channel until it 

reaches a position where it may be controlled 

by the ebb-tide cmTent from the strait. Along 

a zone which is common ground for the two 

currents the sand is probably drifted to and 

fro, but, inasmuch as the directions of the currents intetsect at an angle, the course of each 

grain is a zigzag, and the resultant effect is a 

drifting southwestward in the dir·ection of the 

a.xis of the bar. 

' Coast Pilot of California, Oregon, and Washington, 4th od., p. 227, 

lSS!l. 

The direction of sand movement along the 

bar crest in its medial or western portion probably depends on the general moveme~t of water 

parallel to the coast. Ac~ording to Davidson, 

that movement is northward, but the evidence 

he cites pertains ahnost wholly to more northerly portions of the coast. At the lightship 

moored 4 miles outside the bar the surface current is found to vary with the direction of the 

wind. If Davidson's view is c<;>rrect, the sand 

drifted along the bar crest helps to maintain 

the 4-fathom bank. In any case, an important 

factor in determining the existence of the bank 

is the relative weakness in that direction of 

the ebb current from the strait. 

THE EFFECTIVE TIDAL PRISM. 

During the rising of the tide water flows from 

the ocean to the bay; while the tide is falling 

the flow is toward the ocean. The general 

measure of the volume whiqh thus passes 

through the strait is the space between the 

FIGURE 11.-Ideal section of effective tidal prism in a large bay. 

plane of high tide and the plane of low tide 

within the bay, a space known as the tidal 

prism. For a small bay, in which high tide 

occurs everywhere at nearly the san1e time, 

this general definition suffices, but the San 

.Francisco Bay system is so . extensive that 

high tide reaches different parts at very different times, and it is necessary to take account 

of these differences in estimating the tidal 

discharge. In seeking a more specific definition there is .advantage also in substituting for 

the times of high tide and low. tide the two 

times of slack water which follow the ti1nes 

of high and low. The volume of water which 

flows through the bay between any tin1e of 

slack and the time of the following slack is 

equal to the volume of the space between the 

"water plane," or position of the water surface, 

at the first time and the water plane at the 

second. In the diagrammatic section ·of a bay 

in figure 11 the full lines represent the. water 

planes of two slack-water times. The broken 
72 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

lines represent the levels reached by the high 

water and low water of the tidal wave as it 

travels tl;rrough the bay, and these levels, 

although neither of them is occupied simultaneously through its whole extent by water 

surface; are usually called the high-water and 

low-water planes. The space between the 

slack-water planes, or the effective tidal prism, 

is less than that betwe·en the "planes" of high 

tide and low tide. 

In an estuary so long that the passage of the 

tidal wave occupies several hours the planes 

of the two slack-water times may intersect, and 

they may even cross ·more than once. Figure 

12 repr.esents a hypothetic case in which there 

are two intersections, the plane of one slackwater time being represented in profile by the 

line AEH G B and the plane of the other by the 

line OEFGD. It is evident that the effective 

tidal prism is equal to the volume of the space 

represented in section by the area AEO, minus 

the space represented in section by the area 

EFGH, plus the space represented in section 

c 

FIGURE 12.-Ideal section of effective tidal prism in a long estuary. 

by the area BGD. The tidal oscillation between E and G reduces instead of augmenting 

the tidal discharge and therefore reduces the 

force of the tidal currents at the mouth. of the 

estuary, and this general fact is of special 

interest in the present connection because it is 

illustrated by the tidal phenomena of the San 

Francisco Bay system. 

The position AO in figure 12 may represent 

any cross section of an estuary, and for each 

section there is a separate and different effective 

tidal prism determining the tidal volume at 

that section. For the discnssion of conditions 

in the San Francisco Bay system we need to 

consider the volume at several points, but especially at the bar outside the Golden Gate. It 

happens, however, that the available data 

apply muqh better to the determination of the 

volume flowing through the narrowest part of 

the strait-at Fort Point-than to the determination of that flowing across the bar, and 

computations will for that reason be made for 

the Fort Point section. The velocities at bar 

and strait are so intimately related that, for 

the purposes of this investigation, the difference in locality is unimportant. 

MEAN TIDAL VOLUME AT THE GOLDEN GATE. 

THE OPEN-WATER EFFECTIVE PRISM. 

The tidal volume is greater for some tides 

than for others. Computation will first be 

made of the volume corresponding to a tide of 

average range. It is convenient to consider 

separately, first, the effective tidal prism of 

the open water of the bays, and second, the 

additional storage of tidal water on marshes. 

The chief body of data required for the computation of the effective tidal prism is reFIGURE 13.-Cotidallines in the San Francisco Bay system. 

corded by the United Stat.es Coast and Geodetic Survey in the Tide· Tables. Those data 

include, for many stations about the shores of 

the bay, (1) the mean range of tide, (2) the 

average difference in time between high water 

at the station and high water at Fort Point, 

and (3) the average difference in time between 

low water at the station and low water at 

Fort Point. To complement these data it is 

necessary to know also the time interval at 

the Golden Gate between high water and the 

following slack water, and the interval between 

low water and the following slack water; and 

to obtain . this infQrmation special series of 

observations were undertaken in September, 

1914. A record and discussion of the obser-
RELATIONS OF DEBRJS MOVEMENT TO THE GOLDEN GATE BAR. 73 

vations is contained in Appendix A (pp. 108-

120). The resulting estimates of average slack-. 

water intervals are, after high water, 57 minutes; after low water, 114 minutes. 

The cotidallines in figure 13 show by halfhour intervals the successive positions of the 

tide wave (high water) as it moves through 

the bays. 1 · 

tervals between slack water at Fort Point 

and the extremes of tide at the stations, the 

slacks which severally follow high tide and low 

tide at Fort Point being distinguished as highwater slack and low-water slack. The fifth 

column gives for ea~h station the mean range 

of tide. The numbers in the si~th column 

were computed from those in the third, fourth, 

TAJnJ~ 15.-Datajor mean effective tidal prism of San Francisco Bay system as a.ffecting the discharge at the Golden Gate. 

High water Low water Range at station at station 

follows follows Mean effective 

Station. Dis- high-water low-water range for cur- tance. rent at slack at slack at of tide. Golden Golden Golden Gate. Gate by- Gate byMiles. Minutes. ~Minutes. Feet. Feet. 

Fort Point, Golden Gate ................................... 0 - 66 -107 3. 9 2. 9 

San Francisco Bay: 

Mission Street wharf ........................ · ... : . ...... 6 - 38 - 76 4. 2 3. 7 

Goat Island Light ...................................... 6 - 38 - 74 4.0 3. 5 

Avisadero Point ....................................... 11 - 34 - 67 4. 6 4. 1 

San Mateo Point ....................................... 21 - 21 - 51 5. 1 4. 8 

Guano Island ........................................... 24 - 18 - 37 5. 7 5. 5 

Coyote Hill Creek entrance ............................. 27 - 6 - 31 5. 7 5.6 

Redwood Creek entrance ................................ 28 - 10 - 36 6. 1 5.9 

Ra venS\VOOd ........................................... 30 - 9 - 25 6.0 5. 9 

Alcatraz Island Light ................................... 3 - 55 - 94 3. 6 2.9 

Sausalito ............................................... 3 - 61 - 88 3. 7 3.0 

Angel Island .......................................... 4 - 57 - 80 3.8 3. 2 

West Berkele~·-·· ..................................... 10 - 21 - 56 4. 3 4.0 

San Quentin oint ...................................... 13 8 - 44 4. 1 3. 95 

Brothers Light ......................................... 14 - 5 - 41 4.2 4.0 

San Pablo Bay: 15 4 43 4. 0 3.85 ~~i~~~fl:O~~~~-~---.·_·_·_·_· .· ~::::::::::::::::::::::::::::: - - 22 34 12 4. 7 4. 6 

Petaluma Point ........................................ 24 0 - 15 4. 5 4. 5 

Sonoma Creek entrance ................................. 26 16 1 4. 5 4. 5 

Car){inez Strait: . are Island Light .. : ................................... 27 39 18 4. 8 4.6 

}j~~~~t~~~~: .·. ·. ·.: : : : : : : : : : : : : : : : : : ·: : : : : : : : : : : : : : : : : . : : : : 28 49 32 4. 7 4. 4 

31 74 57 4. 7 4.0 

Suisun Bay: 

Seal Bluff .............................................. 38 81 78 4. 9 3. 8 

Suisun Creek entrance ................................. 39 93 90 4. 7 3. 3 

Sacramento River: 

Collinsville ............................................ 49 135 148 3. 9 1.4 

Sacramento ........................................... 113 417 517 1. 5 -1.0 

San Joaquin River: 

Ant.1och ............................................... 53 168 186 3. 9 0 

Stockton a .•.......••.•.....•................••.•...... 94 414 493 2. 5 -1.4 

a 'L'bo Intervals and mean range for Stockton were furnished by an officer of the Engineer Corps, U. S. Army, with the statement that they are ap'{)roxlmate only. . . 

In Table 15 the first column contains the 

names of stations at which tidal constants 

available for the discussion of the prism have 

been determined. In the second column are 

distances along the lines of tidal propagation. 

In the third and fourth columns are time in1 ~l~ho timo unit is tho lunar hour, 3.5 per cent larger than the meantime hour. A similar plot for low tide would be somewhat different, 

1\S tho low tide travels more slowly. The distance covered by high tide 

in 3 hours requires for low tide about 3.8 hours. 

and fifth (with the aid of certain other tidal 

elements not here stated) and show for each 

station the change in water level occurring 

between two consecutive times of slack water 

at Fort Point. All quantities are annual 

means. 

The heights of the effective tidal prism (sixth 

column), or the effective ranges of tide for the 

stations, were plotted on a map and by their 
74 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

aid the average height of the effective prism 

was estimated for each of several divisions of 

the bay system. These averages are contained in Table 16 (p. 75). 

Certain of the ranges were used also in the 

construction of figure 14, where· they are 

· plotted on ~ scale of distances which represents 

the route of the tide from the Golden Gate, 

through the northern part of San Francisco 

Bay, San Pablo Bay, Carquinez Strait, Suisun 

Bay, and Sacramento River, to the city of 

Sacramento. The plot does not include data 

for the southern arm of San Francisco Bay nor 

for San Joaquin . River'. The horizontal line 

Feet 

+6 

Pablo Bay and beyond that part descends. 

The effective range changes from positive to 

negative a few miles above the mouth of 

Saoramento River and should become again 

positive a few miles above Sacramento. Between Collinsville and Sacramento accurate 

observations are lacking, but somewhere in 

this tract the negative effective range has a 

maximum. 

The facts illustrated by this curve are (1) 

that the volume of tidal current through the 

Golden Gate which corresponds to mean range 

of tide realizes a large fra.ction of the full effect 

in San Francisco Bay, (2) that it realizes nearly 

Sacramento River 

--------- ~ Cl) 

E 

~ 0 

1.. 

tO 

Cil 

::: " ::J .!!:! " iD 

> C1l Vl 

<U 

(f) ~ 

0 

(.) 

-4 0 29 . 40 60 80 100 120 Miles 

FIGURE 14.-Profiles of tidal range along the line of the main channel from tho Golden Gate bar to Sacramento. AB, Mean range of tide 

=average local high water above average local low water; CD, effective mean range, computed with reference to tidal volume at the Golden 

Gate; EF, effective tropic range .. 

marked 0 is the zero of tidal range. The 

circles represent local mean ranges, and their 

irregularities are related to the fact that the 

stations do not stand in line but are scattered 

about tre shores of the bays. The curve AB, 

associated with them, is intended to show the 

variation of mean range along the line of the 

main cha:J!nel. The range at Sacramento was 

determined in 1857, before the river channel 

had been greatly modified by mining debris. 

The ranges effective for the· times of slack 

water at the Golden Gate are indicated by 

crosses, and only those for stations near the 

main line of channel are plotted. The corresponding curve, GD, is close to the mean 

range curve in the part corresponding to San 

the full effeot in San Pablo Bay, (3) that it 

realizes a rapidly diminishing fraction of the 

full effect for Suisun Bay and the lower rea.ches 

of Sacramento River, and ( 4) that the discharge is. reduced ·by tidal volume for higher 

reaches of Sacramento River. So far as tides 

of mean range are concerned, the abridgment 

of tidal storage by artificial means may weaken 

t-he currents at the Golden Gate and the bar, 

may strengthen them, or may not affect them, its 

relation to the currents depending on locality. 

In computing the tidal volume through the 

Golden Gate account is taken of the effective 

ranges and the associated areas. So far as 

practicable the areas of the water bodies were 

measured on charts made before the invasion 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXVIII 

A DELTA MARSH BORDERING SAN JOAQUIN RIVER. 

The foreground shows the dominant vegetation of the tidal marshes where the water is fresh or nearly 

fresh. The bushes mark the position of the natural levee, here low. An artificial levee may be faintly seen above the rushes. The work of reclamation was in progress at the date of the view, August 31, 1905. 
U.S. GEOLOGICAL SURVEY I>ROFESSIONAL PAPER 105 PLATE XXIX 

A. A RECLAIMED DELTA MARSH, BORDERING SACRAMENTO RIVER. 

In the center is the artificial levee, which stands on the natural levee. The river is above mean stage and its surface is several feet higher than the land seen at left. The orchard stands on the inner slope of tlie natural 

levee. (Compare Pl. XXVIII.) 

B. TIDAL MARSH NORTH OF SUISUN BAY, WITH TIDAL SLOUGH IN FOREGROUND. 

Photographed in June, 1905. 

TIDAL MARSHES. 
R-ELATIONS OF DEBP.JS MOVEMENT TO THE GOLDEN GATE BAR. 75 

of the bays by mining debris, but that was not 

possible for every body of water. The dates 

of the siD·veys are recorded along with the 

areas· in Table 16. Each tabulated area of a 

bay is the arithmetic mean of the high-water 

area. and the low-water area as charted. The 

high-water line of the charts represents the 

water margin at approximately mean highwater stage, but the low-water line d.oes not 

represent the margin at the coordinate mean 

low-water stage. It is the co.ntoiD· of the 

"plane of reference" and represents the margin 

because of peculiarities in the configuration of 

marsh land the relation of the effective prism 

to the en tire prism is not the s arne for marsh 

land as for open water. A special in:vestigation 

was made of the natural laws affecting the 

storage of tide water by marsh lands. 

The typical tide marsh of the region is a 

plain traversed by a branching system of 

sloughs. At low stages of tide the plain· is 

uncovered and only the trunk sloughs contain 

water. These communicate with the adjacent 

bay. As the tide rises in the bay there is a 

'rAum !G.-Computation of the nwan tidal volume at the Golden Gate, so far as given by the effective tidal prisms of the bays 

and other bodies of open water. 

Body of water. Year or years Area at Mean depth Volume of effecof survey. half tide. of effective tive prism. prism. 

San.Francisco Bay: Sq. miles. Feet. Cubic feet. Southern part ................................... 1857-58 188. 3 4. 7 25,660,000,000 

San ~~bl~~u~:~~~-- ·_ ~ ~ ~ ~ ~: ~::::::: ~:::::::::::::::::: 1855 77.4 3.7 7,980,000,000 

1856 106.8 4.45 13,250,000,000 

Napa Creek ......................................... 1856,1860 5.0 4.3 680,000,000 

Carquinez Strait ..................................... 1857,~866 8.0 4.25 950,000,000 

1866-67 a 47.9 3. 1 4,140,000,000 ~~~~~~~~~. ru~~r-. -_:: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1886,1906-1908 8.8 - . 27 - 64,000,000 

San Joaquin River .................................. 1886,1907-1912 16.8 -1.80 - 843,000,000 

459.0 ................. 51,753,000,000 

a 1'his area includes Sacrnmonto River to Collinsville nnd San Joaquin River to Antioch .. 

at the .mean of lower low-water stages. The 

depression of mean lower low water below 

mean low water is about one-fourth of the 

mean range of tide. In consequence of this 

discrepancy the low-water area obtained from 

the charts is too small and ~o is the computed 

hu.If-tide area. If a correction were to be applied it would increase the estimate of total area 

by about 1.5 per cent and would correspondingly increase the estimate of tidal volume. 

The river areas given in the table include 

some of the more important sloughs. 

WATER STORAGE ON 'MARSHES. 

Tho 1narsh lands that border tho bays (see 

fig. 15 and Pis. XXVIII and L~IX) are·subject 

to overflow by the tides. They receive water 

'.v.hile the tide is rising and return it while the 

tide is falling, and the storage thus accomplished is additional to the storage measured 

by the tidal prism of the open water. Each 

marsh tract has in fact a tidal prism, and a 

part of that prism is effective, in the same sense 

as the effective prism of the open water; but 

flow inward through the sloughs, and as it 

falls there is a flow outward. If the tidal oscillation is relatively small the entire movement 

is confined to the sloughs; if it is relatively 

large the plain is flooded. In the special investigation just mentioned a station was estab- · 

·lished in a trunk slough near its mouth, a 

record was made of the rise and fall of the tide, 

the inflow and outflow were measUJ·ed, and the 

observations were made in continuous series 

to cover tides of several types. As the record 

and discussion of the observations occupy considerable space they have been relegated to an 

appendix (pp.l23-138), and only the generali-. 

zations will be given here. 

The marsh specially studied is that served 

by Ravenswood Slough and borders the south 

arm of San Francisco Bay. The mean range 

of tide in the adjacent part of the bay is 6.0 

feet, and the great tropic range. is 9.3 feet. 

The average tidal storage by· marsh and slough, 

equivalent to the mean tidal prism of the tract, 

equals a layer of water 0.60 foot deep over the 

entire tract. It is convenient to speak of this 
76 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

as· the depth of storage. For the great tropic large. It is assumed with confidence that in 

tides, which in these bays are ebb tides, the regions where the range is less the depth of 

average depth of storage is 1.27 feet; for the storage on marsh lands is also less; but the 

FIGURE 15.-Marsh lands and bodies or open water affecting the tidal volume at Golden Gate bar. 

flood tides preceding the great tropic ebbs it 

is 0.87 foot. 

The observations were made in a place where 

the open-water tidal range is exceptionally 

reduction in storage is not necessarily proportional to the reduction in range. Vegetation 

has much to do with the physiography of a 

tide marsh, and it is possible that its control 
RELATIONS OF DEBRIS MOVEMENT TO THE GOLDEN GATE BAR. 77 

tends toward uniformity of high-water depth 

on the marsh plain, in which case the variation in depth of storage would be less rapid 

than the variation in open-water range. The 

subject is further complicated by the fact that 

the mm'Sh vegetation is not everywhere. the 

same. The higher levels of all the marshes 

m·e marked by samphire (Salicornia) and alkali 

grass (Distichlis), but the flora of the lower 

nnd broader parts varies with the salinity of 

the water. About San Francisco Bay the 

. dominant plant is creek sedge (Spartina); 

about Suisun Bay and on the river deltas the 

dominant plants are cat-tail rush (Typha) and 

tule (S cirpus). In the lack of de:fini te information as to the influence of these factors, the 

computations have in general assumed that 

the storage constants for the various marshes 

al'e proportional to the tidal ranges of adjacent 

bodies of open water, but in computing the 

storage volumes of the lm·ger marshes an allowance was made for the fact that the tidal range 

is less at a distance from the open water than 

near it. 

Where the tide·enters a deep bay through a 

deep, broad strait, the sequence of discharges 

in the strait follows a simple law. If the discharges are plotted with reference to time, the 

resulting curve is symmetric and is approxinlately a sine curve. Such a curve is shown 

in the upper part of figure 16, where flood 

discharges are reckoned downward from a base 

line and ebb discharges upward. 1 Departures 

fron1 the type form are unimportant. The 

other thTee curves of the figm·e show sequences 

of discharges for tidal marshes and are based 

on the Ravenswood observations. It will be 

seen that they depart widely from the sinecm·ve type. Their most striking peculiarity 

is that the maximum discharge for both flood 

and ebb occm'S near the change from flood to 

ebb-that is, it occurs when the water stage is 

high. This is connected with two facts-first, 

that the section of the current in the slough is 

1 Flood and obb, implying motion in opposite directions, arc usually 

chnroctorizod by opposite signs, but thoro is no ftmdamental reason 

why ono rather than tho other should bo regarded as positive. As a 

matter of convenience obb discharges arc hero treated as positive; and, 

equally ns a matter of convenience, flood velocities and discharges arc 

treated as positive in Appendixes A and B. In tho appendixes currents 

arc discussed in relation to tho tidal oscillations which cause them, and 

flood currents arc made positive because they arc caused by positive 

(rising) tides. In tho present connection wo arc concerned especially 

with tho transporting power of tho obb current in the Golden Gate, and 

with reference to that current obb discharges in the marsh sloughs are 

positive. 

much larger at high water than at low; second, 

that. the water area in the marsh tract (the 

area receiving or delivering water) is much 

larger at high water than at low. A relatively 

small volume of water is moved in filling or 

emptying the sloughs, but a relatively large 

volume is 1noved in flooding or draining the 

marsh plain. 

The curves pertain severally to tides giving 

the average amount of marsh storage, to tropic 

~ONE TIDAL PERIOD 

~ 

0 

..J 

FLOOD TIDES EBB TIDES 

0: 

w 

1-

4: 

~ 

~ 

0 

..J 

FIGURE 16.-Curves showing progressive variations of discharge in a 

channel serving a tidal marsh. Vertical distances represent discharge, 

ebb discharges being reckoned as positive, flood discharges as negative. 

Horizontal distances represent time, tho unit of time being the period 

of a flood or ebb tide. The lower three curves are copied, with change 

of scale, from curves XII, XIV, and XIII of figure 27 and curves IX, 

VIII, and X of figure 26. The unit of the time scale is tho tidal period. 

:Measured in hours and minutes the ebb periods are longer than the 

flood, and this difference is greater for large tides than for small. It is 

also relatively great for marshes at a distallce from the Golden Gate. 

tides, and to very large tides. Their use will 

be illustrated by an example. It is to be 

premised that as the . ordinates of the curves 

represent discharge, or the rate of passage of 

volume of water, the space between any curve 

and its base line represents the total volume of 

water passed, and the space between a portion 

of a curve and the corresponding portion of its 

base line represents the volume of water passed 

in the corresponding time. 
78 HYDRAULIC-MINING DEBR.IS IN THE SIER.RA NEVADA. 

The average depth of tidal storage for the 

marsh served by Suisun Slough is 0.47 foot. 

It is desired to find what portion of this is 

effective with reference to ebb discharge at the 

Golden Gate. When the ebb begins at the 

Golden Gate, the flood is stili running at the 

entrance to Suisun Slough, and it will continue 

to run for a time represented, on the second 

curve of figure 16, by the distance as. After 

the ebb ends at the Golden Gate it will continue to run at the slough entrance for a time 

represented by the distance cf. The verticals 

ab and cd having been drawn, the area sdc represents the volume delivered by the slough 

during the ebb period at Golden Gate, and 

areasdc 

area sd(c X 0.47 f~ot 

tribution of Suisun Marsh to the discharge at 

the Golden Gate is 

( 

area sdc area sab ). 0 f ---- X .47 oot. 

area sdfc area sbea 

The product of this depth by the area of the 

Suisun Marsh tract is the effective volume of 

tidal storage by the tract.1 

The computations involved other factors, 

to which due attention was given, but only 

their general character will here be indicated. 

The Tide Tables deal with the rise and fall of 

the water surface and define four epochshigh water at the Golden Gate, low water at the 

Golden Gate, high wu.ter at a slough mouth 

(Suisup., for example), low water at the slough 

mouth. The flood and ebb curves of figure 

16 begin and end with epochs of slack water, 

TABLE 17.-Average tidal storage on marsh tracts of San Francisco Bay system, as affecting tidal discharge at the Golden 

Gate; computed for conditions before encroachment by levees. · 

Effective Effective 

Marsh tract. Area. depth of volume of 

storage. storage. 

Bordering San Francisco Bay: · Square miles. Feet. Cubic feet. 

South of Newark and Ravenswood .................................. 26.8 0.56 418,000,000 

East side, Newark to Berkeley ............................ _ ....... 33.4 • 53 493,000,000 

West side, Ravenswood to San Mateo ............................... 26.4 . 52 38.3,000,000 

West side, San Mateo to San Francisco ......................... _ ... 7. 1 .40 79,000,000 

North of Goat Island ................................ , ..... _ . _ ...... 8.0 . 38 85,000,000 

Bordering San Pablo Bay: 

Served by Gallinas, Novato, Petaluma, and Tolay creeks ......... _ .. 41.0 . 39 446,000,000 

Served by Sonoma Creek .......................................... 28.0 • 38 297,000,000 

South shore ............................................ _._ .. _ ..... 2.0 .44 25,000,000 

Borfe~i~:ds~k~a~~~iver · · · · · · · · · · · ·. · · · · · · · · · · · -· · · · · · · - -· · · · · -· · · · · · 31.8 • 29 257,000,000 

Served by Suisun Creek .......................................... 35.0 . 22 171,000,000 

Served by Montezuma Creek; main part ............... ·- ............ 31. 7 .19 168,000,000 

Island region and south shore ............................ --.· .. -- .. -1 36. 0 . 28 281,000,000 

I 3,103,000,000 

River deltas: 

Sacramento ................................ ~ ..................... 168.0 -.116 - 544,000,000 

San Joaquin ...................................................... _ 365. 0 -.173 -1, 760, 000, 000 

840. 2 ..................... -2, 304, 000, 000 

799,000,000 

represents the corresponding depth of storage. 

Similarly the area sab represents the volume 

received by the slough during the ebb period 

at the Golden Gate, and 

area sab · ' 

b X 0.47 foot areas ea 

and the use of the data contained in the curves 

requires the time differences between each 

of the high-water and low-water epochs and 

the associated (following) slack-water epochs. 

The time differences at the Golden Gate are 

discussed in Appendix A; the time differences 

at slough mouths in Appendix B. · 

represents the corresponding depth of storage. 

The depth ~f storage measuring the net con1 The statement of this example is intended to show the essential relation of the curves to effective volume of storage. For the actual work 

of computation the data embodied in the curves were put in more convenient form. 
R.ELATIONS OF DEBF.JS MOVEMENT TO THE GOLDEN GATE BAR. 79 

The results of the computations are presented 

in Table 17. The arens there given-the areas 

used in computing the volumes of tidal 

storage-are areas of original marsh la:nd, includi_ug associated sloughs, and differ materially frmn the areas now flooded by the tides. 

Most of the tracts have been more or less 

abridged by the work of reclamation, and the 

abridg1nent has been especially great in the 

delta tracts, which are largest of all. Wherever 

two of the indicated marsh tracts adjoin there 

is Inore or less interchange of waters, so that 

their common boundary has not a fL-x:ed position, and in such places a position was arbitrarily assigned to ·it. 

The computations for the deltas involved 

much interpolation, because the data are 

imperfect. There were few trustworthy tide 

observations and the system of arteries for the 

flow and ebb of tide water was not mapped 

until after its modification by levees . 

. In Table 18 the storage volumes for bays, 

rivers, and marshes are assembled from Tables 

16 and 17 and are compared by means of percentages. Although the area of the marsh 

lands is 8~ per cent greater than the area of 

open water, their effective storage, with reference to. the Golden Gate discharge, is much 

~m.aller. Considered without respect to sign, 

It IS one-tenth that of the open water. 

'!'ABLE 18.-Average volume flowing through the Golden 

Gate ~·uring ~flood or ebb tide, with indication of the chief 

assocwted umts of storage. 

[Dasod on data of Tables 16 and 17.] 

Volume of storage. 

Division of San };ran- Millions of cubic Per cent. cisco Bay system. feet. 

Open Marsh. Open Marsh. water. water. 

San Francisco Bay: 

Southern part ..... 25, 660 1,373 48.82 2.61 

Northern pru·t ..... 7,980 85 15. 18 .16 

Sau Pablo Bay ........ 13,250 768 25.24 1. 46 

Napa H.iver ........... 680 257 1. 29 . 49 

Cat·quinez Strait ....... 950 ........ 1. 80 . ....... Suisun Bay .......... 4,140 620 7.88 1. 18 --

52, 660 3,103 100.21 5.90 

Sacramento Delta .... -64 -544 -.12 -1.04 

San J'oaquin Delta ... -843 -1,760 -1.130 -3.35 

-907 -2,304 -1.72. -4.39 

51, 753 799 98.49 1.51 

52,552 100.00 

TROPIC TIDAL VOLUME AT THE GOLDEN GATE. 

To the .results obtained by the preceding 

computations and estimates there is an important qualification. They are based in chief 

part on the constants of a tide of average siz·e, 

but the lvork of a large tide differs materially 

from the work of a small one, and the n1ean of 

effects of all tides is Il;Ot the same as the effect 

of a tide of mean size. The particular effect 

which concerns· us in this discussion is the 

modeling. of the bar, and that depends on 

velocities of currents. The relative efficiency 

of large and small tides is partly illustrated by 

~gure 17, w~ere horizontal spaces represent 

trme and vertical spaces velocity. Each curve 

shows the sequence of velocities during an ebb 

tide, the middle curve corresponding to an 

A c 

.B 

FIGURE 17.-Diagram illustrating the relative efficiency of large and 

small tides for tho transportation of debris. Horizontal distances 

represent time; vertical distances represent velocity of tidal current. 

average tide and the others severally to a very 

large and a very small tide-the data being 

taken from the prediction tables for Fort Point. !f the ordinate AB represents the velocity that 

Is barely competent to move sand on the inner 

slope of the bar, the portions of the horizontal 

line AO intercepted by the curves show the 

relative periods during which cur~ents of the 

thr~e tides work on the bar. The an1ount' of 

work accomplished by either in a unit of time 

is proportional to a. power of its velocity not 

less than the third. 1 So the potency of th~ 

large tide exceeds that of the average tide in a 

ratio which is far greater than the ratio between the ·areas embraced by their respective 

velocity curves. For this reason it is desirable 

to learn the volumes of large tides as they pass 

1 See U.S. Geol. Survey Prof. I>aper 86, pp. 100-161, 1914. 
80 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

the bar and also the characteristics of the 

effective prisms associated· with them. 

The more important factors determining 

large tides in the San Francisco bays are, first, 

the reinforcement of the lunar attraction by 

the solar (giving spring tides); second, the 

nearest approach of the moon to the earth 

(giving perigee tides); and third, the greatest 

departure of the moon from the plane of the 

earth's. equator (giving tropic tides). The 

third factor is the chief cause of the inequality 

of the two tide oscillations occurring on the 

H.H.W. 

FIGURE 18.-Sequcnce and relation of tides and currents in San Francisco Bay when the moon is far above or below the plane of the earth's 

equator. The upper curve gives w~ter stage (vertical) in relation to 

time; the lower gives discharge in relation to time. L. H . W. , lower 

high water; H. L. W., higher low water; H. H. W., higher high water; 

L. L. W., lower low water. Flood discharges are laid off upward from 

CD; ebb discharges downward. 

same day. The first and second affect the 

volume of water crossing the bar, but do not 

materially affect the percentages of that volume which are contributed by the effective 

prisms of individual bays and tracts of marsh 

land. The third affects both volume and per-

.centages, and its influence on volume is greater 

than the joint influence of the other two factors. 

. In figure 18 the horizontal scale represents 

time and is the same for both curves. The 

upper curve shows the tropic sequence of tides 

in San Francisco Bay, the cycle of four tides 

filling one lunar day (24.8 hours). Beginning 

with the lesser of the two high waters-the 

"lower high water"-we have fust a fall of 

moderate amount, then a rise of greater amount 

(to higher high water), and then a fall through 

the extreme range of the tide (to lower low 

water), followed by a second rise which completes the cycle. Each rise is associated with 

an inflow from the ocean, or. flood current, and 

each fall with an outflow, or ebb current. The 

order in which the tides occur, the lower.low 

water coming immediately after the higher 

high water, causes one of the ebb currents to 

have greater volume than either of the flood 

currents. The lower curve of the figure shows 

the sequence of currents, the zero of current, 

or slack water, being represented by the line 

CD. Vertical· distances represent discharge, 

or the volume of water passing through a given 

cross section of channel in a unit of time; the 

flood discharges are laid off above the zero 

line, and ebb discharges below. The sum of 

discharges during the period of one of the currents, or the total volume of that current, is 

represented by the area between the corresponding part of the curve and the zero line; 

for example, the volume of the final flood current is shown by the area between D EF and D F. 

Because, on the .average, tidal inflow and outflow are equal, the curves have been so drawn 

that the sum of the two flood areas equals the 

sum of the two ebb areas. 

The great ebb current, associated with the 

fall from higher high water to lower low water, 

is the greatest of the currents; and next to it in 

magnitude is the flood current which follows it, 

corresponding to the rise of the tide from lower 

low water to lower high water. 

The curve of velocities is similar to the curve 

of discharges but is not identical in form. 

Velocity would be strictly proportional to discharge if the sectiorral area of the channel were 

constant, but that varies with the stage of tide. 

When the tide is high the section~! area is relatively large, and a relatively low velocity suffices to produce the discharge. The times of 

the tides and currents are so related (see fig. 18) 

that the maximum flood discharges occur when 

the water stage is above its mean position, and 

the maximum ebb discharges occur w4en the 

water stage is below its mean position; and as a 

result the greatest ebb velocity exceeds the 

greatest flood velocity by a ratio which is larger 

than that of the greatest ebb discharge to the 

greatest flood discharge. 
RELATIONS OF D:EBlUS MOVEMENT TO THE GOLDEN GATE BAR. 81 

It is estimated that the maximum discharge 

during the great ebb is about 10 per cent greater 

than the n1aximum discharge of the following 

flood. The extent to which the contrast of 

velocities is enhanced by the factor connected 

with water stage varies with locality, being 

affected largely by depth of channel. In the 

Golden Gate, where the channel is deep, it may 

amount to l or 2 per cent; over the Pinole Shoal 

in San Pablo Bay it probably exceeds 25 per 

cent. Thus there is a notable difference between the speeds of the strongest tropic ebb 

current and the strongest tropic flood current. 

When the tides lack the tropic characters, 

and the four currents of the day have approximately the san1e volume, the ebb velocities ~re 

their alternating currents make them peculiarly . 

efficient as conveyors of debris to the bar. 

For these reasons I have made a separate · 

computation of the average effective tidal 

prism which determines the volume of the great 

tropic ebb current. The computation and · 

estimation, of which the · results appear in 

Table 19, followed the lines already indicated 

for the mean tidal volume. · 

. The curve of effective range for the route of 

the tide from Golden Gate to Sacramento 

appears in figure 14 (p. 74) as the line EF and 

is well controlled by the data as far as Collinsville. The interpolated portion between· Collinsville and Sacramento is largely hypothetic, 

but there is no reason to question its indication 

'fABLE 19.-Estimate of the average volume of great tropic ebb currents at the Golden Gate as dependent on the effective tidal · prisms of bays, other bodies of open water, and marsh tracts. . 

Effective range of Volume of storage, Relative volume of 

in millions of cu- storage, in tide, in feet. per bic feet.a cent. 

Division of San Francisco Bay system. 

Open Marsh. Open Marsh. Open Marsh. water. water. water. 

San Francisco Bay: 

Southern part ............................... 7. 7 1.03 40,402 2,690 43.94 2.92 

Northern part ............................... 6.05' . 87 13,000 194 14. 19 . 21 

San Pablo Bay .................................. 7. 15 . 72 21,280 1,425 23. 15 1. 55 

Napa River ..................................... 7.0 . 55 1,064 487 1. 16 . 53 

Carquinez Strait ................................. 7.0 .......... 1,560 .............. 1. 69 . ........... Suisun Bay ........................ · ....... -.· ..... 5.6 . 52 7,480 1,488 8. 14 1. 62 

River deltas: 

Sacran1ento ............................ __ .... . 95 .108 225 506 . 24 . 55' 

San Joaquin ................................ . 49 - . 013 229 -132 -.14 

85,290 6,658 I 92. 76 7.24 

a Volume at the Golden Gate, 91,948,000,000 cubic feet. 

still somewhat greater than the flood, but the 

difference is then comparatively small. 

The superior strength of ebb currents determines the direction of transportation of debris 

along the bed of the channel. At most points 

the currents in each direction are so :me times 

strong enough to :move debris, so that it is 

dragged both seaward and landward, but the 

ebb currents accomplish most, and the net 

result is a progress toward the ocean. So the 

tropic tides are of special importance in connection with the harbor entrance, not only because the volume of the great ebb current gives 

to it peculiar power for the control of the position 

of the 'bar, but also because the inequalities of 

that the point at which the tropic effective 

range becomes negative is farther upstream 

than the corresponding point for the mean-tide 

effective range. 

The estimates for marsh lands are less trustworthy than those contained in preceding 

tables. Certain assumptions made (in Appendix B) as to the lag of slack water affect only 

moderately the computations of mean-tide 

storage on marsh lands, but they affect more 

seriously the computations of tropic-tide storage. This qualification is, however, only a 

single phase of a more general qualification. 

The empiric methods employed in the discussion fail to take proper account of the kinetic 
82 HYDRAULIC-MINING DEBR1S IN THE SIERRA NEVADA. 

elements of tidal phenomena, and the consequences of this failure are peculiarly apparent 

in the treatment of the invasion of marsh 

lands by tropic tides. 

Despite this qualification it is my belief that 

the system of percentages (Table 19) based on 

the tropic-tide data is preferable to that based 

on mean-tide data (Table 18) for the discussion 

of the effect on the bar of local restrictions of 

tidal storage. 

CHECK COMPUTATIONS OF VOLUME. 

surface slope-the relative height of water 

surfaces inside and outside the strait-and 

that varies in a complicated way with the 

varied sequence of tide waves of different 

magnitude. 

TABLE 20.-Relations between general means of tidal range 

in Golden Gate and mean tidal polumes estimated by the 

prism method. · 

Range, Volume, in cu- in feet. hi<;: feet. 

. Mean of all tides .............. . Tl;le preceding estimates of tidal volume m Mean of great tropic ebb tides .. 3. 9 

6. 2 

52,552,000,000 

91,948,000,000 

the Golden Gate rest chiefly on measurements 

by the United States Coast and Ge~detic Survey of the range of tide in different parts of 

the bay system ~nd of the rates of propagation 

of tide waves in the bays.· Their method is 

that of the_ tidal prism. Another group of 

estimates, given in Appendix A, rests on measurements of the velocity, section, and duration 

of certain ebb and flood currents in the Golden 

Gate. In method and data they are indeThe great tropic volume is somewhat greater 

than it would be if the volumes were strictly 

proportional to the ranges, so that the law of 

relation is not that of simple proportion. A 

convenient assumption as to the law is that the 

volumes are proportional to some power of the 

ranges, and t~is assumption yields 

Volume= 10,150,000,000 X ranget. 207 

pendent of the estimates by tidal prism, so The observations of range associated with 

that each group of results may serve to check the observations of current were made at the 

the other .. The comparison can not be made Presidio wharf, where the mean range is 3 per 

directly, because the estimates by tidal prism cent greater than at Fort Point, the station to 

are general averages, whereas the estimates which the other data pertain, and a correction· 

from current observations pertain_ to indi- of ....:. 3 per cent was therefore applied to the 

vidual ebb or flood currents, but a relation measured ranges, They were then entered, 

may be established through the factor of severally, in the preceding eq1u1tion, and the 

tidal range in the Golden Gate. The estimates computed results constitute estimates of the 

by tidal prism correspond to certain average ·volumes of individual tides based on the dis-

. tidal ranges in the strait. The estimates from cussion of the tidal prism. These appear in 

current observations correspond to ranges Table 21, and with t~em are the corresponding 

observed at Presidio wharf while the currents estimates from current measurements. 

were being measured. As shown by the tabvJated differences and 

The bay tides are caused by the tides of the ratios, the discrepancies between the estimates 

ocean outside. Waves generated in the ocean by the two methods are both large and varied. 

traverse the bays, and .the horizontal move- On the whole, the results from the tidal prisms 

ments of water involved in their propagation appear to be smaller than those from current 

are the chief elements of the tidal currents. It observations, but even this generalization is 

is therefore true, in a general way, that the not secure, and the comparisons show chiefly 

greater the amplitude of the tide wave as it that the variation among individual tidal valtraverses the strait the greater the volume of umes does not follow closely the variation of 

the associated transfer of _water. There is a associated amplitudes of tidal waves. Congeneral correlation between range of tide and sidered as a check, the comparisons indicate 

magnitude of current. The correlation· is only that results by the two methods have the 

probably perfect so far as general averages are same order of magnitude, and that the general 

concerned, but it is only approximate with estimates by the method of prisms ~re not 

respect to individual tides, because the volume necessarily inconsistent with the information 

of current depends in part on other factors~/ afforded by a few specific measurements of 

The current is especially influenced by the currents. 
RELATIONS OF .DEBRIS MOVEMENT TO THE GOLDEN GATE BAR. 83 

'J'AnLE 21.-Comparison of estimates of tidal volume at the Golden Gate based on data of the tidal prism in the bays with 

estimates based on current observations in the strait .. 

Sept. 12 Se~t. 13 Sept. 19 Sept. 19 

Ebb. ~ lood. Ebb. Flood. 

4.534 3.534 4.457 4.554 

74,390 41,030 68,950 64,570 

63,030 . 46,690 61,720 63,230 

])ate, 1914 .................. " ....................................... . Type of tide ct • ••••••••••••••••••••••••••••••••••••••••••••••••••••• 

H.ange reduced to Fort Point, in feet ................................... . Volume, in millions of cubic feet: 

(A) Computed from current observations ......................... . (B) Computed from data of tidal prism ................ ~ ......... . 

-11,360 . +5, 660 -7,230 -1.340 

0.85 1.14 0.90 0.98 

Difference: (B)-(A) .......................................... . Ratio of (B) to (A) ................................................... . 

1\{ean of ratios ................................ , ................. _. _ ... . 0.97 

a l!'urthor information as to character of those tides may be found in Appendix A (p. 109). 

TIDAL VOLUMES AT OTHER POINTS. Gate bar. Computations have been made· of 

This inquiry is concerned with the velocity the volume of ·the average great tropic ebb 

of tidal currents and, therefore, with tidal vol- current in Carquinez Strait, in San Pablo 

umes all along the route of d~bris trans porta- Narrows, and on Pinole Shoal, as shown in 

tion from the head of Suisun Bay to the Golden Table 22. 

TABLE 22.-Estimates of the average volume of great tropic ebb currents at San Pablo Narrows, Pinole Shoal, and Carquinez 

Strait as dependent on the effective tidal prisms ofbays, strait, rivers, and marsh tracts. 

San Pablo Narrows (whole volume, 39,800,000,060 cubic feet). 

Effective range of Volume of storage, 

tide, in feet. in millions of c~-

bic feet. 

Division. 

Open wa- Marsh. Open wa- Marsh. ter. ter. 

San Pablo Bay ................................... 6.2 0.85 18,460 1,680 

Napa River ...................................... '6. 7 .71 920 630 

Carquinez Strait ................................ 7.2 .......... 1,600 . ......... Suisun Bay ..................................... 7.3 .71 9,750 2,030 

Sacramento H.iver ............................... 3.0 . 25 710 1,170 

San Joaquin River ................. .' ............. 2.6 .16 1,220 1,630 

·········· .......... 32,660 7,140 . . 

. Pinole Shoal (whole volume, 23,940,000,000 cubic feet). 

San Pablo Bay .................................. 6.2 .......... 1,850 

Napa H.iver ...................................... 6.8 0. 71 950 

Carquinez Strait ................................ 7. 0 .......... 1,560 

Suisun Bay ..................................... 7.2 . 85 9,610 

Sacramento H.iver ................................ 3.6 . 39 850 

Sn.n J'oaquin River ............................... 3.4 . 26 1,590 

··········!·········· 16,420 

Carquinez Strait (whole volume, 20,580,000,000 cubic feet). 

Strait above Point Dillon ......................... . Suisun Bay ..................................... . Sacramento River ............................... . San Joaquin H.iver ............................. . 6.4 

7.1 

3. 8 

3. 7 

0.90 

.44 

. 30 

....... · ... , ......... . 

890 

9,350 

900 

1, 750 

12,890 

·········· 630 . ......... 2,430 

1,830 

2,640 

7,530 

.......... 2,580 

2,060 

3,050 

7,690 

Relative volume of 

storage, 

cent. 

Open wa- ter. 

46.4 

2.3 

4:0 

24.5 

1.8 

3.1. 

82.1 

7.7 

3.9 

'6. 5 

40.2 

3.6 

6. 7 

68.6 

4.3 

45.4 

4.4 

8.5 

62.6 

in per 

Marsh. 

4.2 

1.6 . ... -.. --. 

6.1 

2.9 

4.1 

17.9 

.......... 2.6 . ......... 10.2 

7.6 

11.0 

31.4 

12.5 

10.0 

14.9 

37.4 
84 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

The ebb volume through San Pablo Narrows, 

at the junction of San Pablo and San Francisco bays_ (see fig. 15), is 39,800,000,000 cubic 

feet and is about 43 per cent of that through 

the Golden Gate. The flow through Carquinez 

Strait, estimated for the narrow constriction· 

at Point Dillon, is about half as,great, 20,580,-

000,000 cubic feet. Pinole Shoal, which merits 

special consideration because of the difficulty 

of maintaining a navigable depth there, affords 

·less definite data for the computation of volume. It is part of the bed of the main channel traversing the bay and has a length of 

several miles. The ebb current,. as it follows 

the channel, is continuously augmented by 

water from a broad shoal north of the channel, so that no single estimate of volume can 

change from flood to ebb and from ebb to 

flood) are unknown. 

One of the striking facts illustrated by the 

details assembled in Tables 19 and 22 is that 

the quantity of water contributed by any unit 

of open water or marsh land to the volume of 

current through a channel depends in part on · 

the distance of the channel from the contributing unit. The explanation of this has already 

been given on pages 71-72. To aid the-re,ader 

in making the comparison some of the details 

are rearranged in Table 23. 

The eastern units of the tidal prism contribute a relatively small amount to the current through the Golden Gate and relatively 

large amounts to the currents at points nearer 

by; and, with a single exception, the order of 

TABLE 23.-Comparison of the volumes of tide water contributed, in early years, by certain bodies of water and marsh to the 

tropic ebb currents of different straits and channels. 

Volume, in millions of cubic feet, 

contributed to the current atContributory body of open water or marsh. 

I Golden San Pablo Pinole Carquinez G~te. Narrows. Shoal. Strait. 

Suisun Bay .......................... · ................................. 7,480 9,750 9,610 9,350 

Associated marshes ................................................ 1,488 2,030 2,430 2,580 

Sacramento River ..................................................... 225 710 850 900 

Associated marshes ................................................ 506 1,170 1,830 2,060 

San Joaquin River •........... · ..............................•.......... 229 1,220 1,590 1,750 

Associated marshes ................................................ -132 1,630 2,640 3,050 

apply to the whole of Pinole Shoal. The quantity given in Table 22-23,940,000,000 cubic 

fee:t-was computed for the section opposite 

Point W{lsQn, where the channel is shoalest, 

and the computation assumed, somewhat arbitrarily, that the current at that place includes a contribution from the tidal prism of 

San Pablo Bay equivalent to one-tenth of the 

entire prism of the bay. 

The volume of the tropic ebb on the bar 

outside the Golden Gate (see fig. 10, p. 70) may 

be nearly the same as in the narrows of the 

strait or it may differ materially. Its measure 

includes a large block of tidal prism lying outside the narrows, but there is a compensatory 

exclusion in the region of Suisun Hay and the 

river deltas. The excluded volume can not 

now be determined, even approximately, because certain data essential to the computation 

(the . times at which the eurren ts on the bar 

9,796 16,510 18,950 19,690 

magnitude of the contributions is the inverse of 

the order of distance. It is further to be 

observed that although these contributions constitute the greater part of the entire volume of 

the current in Carquinez Strait, they form relatively small fractions of the currents at points 

farther west. The great marshes of the river 

deltas give to the clirrent in Carquinez Strait 25 

per cent of its volume, to that on Pinole Shoal 

19 per cent, to that through San Pablo Narrows 

7 per cent, and to that through. the Golden 

Gate only 0.4 per cent. 

It has been convenient to phrase the preceding paragraphs in the present tense, and, to 

avoid a possible misapprehension, it is weJl to 

recall to the reader's attention the fact. that 

the computations and their results pertain to 

a condition which no -longer exists. Many of 

the tidal constants employed were derived 

from observations made during early surveys 
RELATIONS OF DEBRIS MOVEMENT TO THE GOLDEN GATE BAR. 85 

of tho bays, and tho areas ascribed to bays and 

marsh tracts are those of tho earliest accurate 

charts and maps available. Tho attempt has 

boon made to determine, as nearly as practicable, tho strength of tidal currents before 

they w~ro modified by the activities .of the 

white man. The shoaling and contraction of 

tho upper bays and the great abridgment of 

tho marshes which have since been brought 

about have changed and in the main reduced 

tho volume. of currents and ha vo doubtless 

chango.d tho range of tho tides as well as the 

times of high water and low water. 

REDUCTION OF TIDAL VOLUME IN THE GOLDEN 

GATE BY ENCROACHMENTS ON THE TIDAL 

PRISM. 

It is proposed now to consider in a quantitative way tho modification of the volume of 

tidal CUl'l'on ts in tho Golden Gate by tho restriction of tho area through which tidewaters 

expand. Most of tho quantities to bo indicated pertain to tho great tropic ebb tide and 

dent that if an embankment is extended from 

the land to EF, tho part between 0 and F 

will reduce the effective prism by the full 

depth of the prism, while the part between 0 

and A will reduce it by a less amount. The 

figures in the second column of Table 24 refer 

to encroachments cutting out the entire depth 

of the prism. 

The case of tide marshes can not be stated 

with equal simplicity. They are flooded and 

drained through long channels, and the process 

consumes time. The estimates of their capacity to store tidal water depend. on measurements of current in the channels (seep. 75 and 

Appendix B), and their statement in depth 

of effective prism does not imply any direct 

measurement of the prism. The tabulated 

depth of effective prism (third column of Table 

24) indicates, when n1ultiplied by the area of 

the marsh tract, the loss to the Golden Gate 

current from the reclamation of the tract by 

levees. It is implied that the reclamation excludes the tide from the sloughs as well as the 

-----------------------------------------.e marsh lands themselv.es; if the marsh lands 

: only are leveed the loss to the Golden Gate I 

~~~=-----------~---,--t--~f current, per unit of marsh area, is less. 

FIGURE 19.-Diagrommutic section or a shore in San Francisco Bay, to 

illustroto tho relation which structures that invade the water bear to 

U1o ofioctivo·tidul prism. 

are derived from tho same datn. as the quantities in Table 19. 

Figure 19 roprosen ts in section a sloping 

shore of a bay. Fill is the·level of high water, 

LL of low water. AB is tho position of tho 

water sm·faco when tho current in the Golden 

Gate changes from flood to ebb; OD its position when tho current changes from ebb to 

flood. Tho height of IlH above LL is the 

range of tide. Tho height of AB above OD is 

tho effective range, or the thickness of the 

effective tidal prism at the locality. Encroachnlonts on tho space between AB and OD, as 

by tho building of piers or the reclamation of 

tide flats, roduco tho volume of current through 

tho Golden Gate. Tho current is not affected 

by encroachments above tho level AB. It is 

not directly affected by encroachments below 

tho level OD but may be affected indirectly if 

such encroachments interfere with the circulation of tide-water through the bays. It is oviIf the depth of effective prism at a given 

locality is multiplied by the area of bay or 

marsh from which the tide is excluded, the 

product will be the volume of water by which 

the tidal current in the Golden Gate is reduced; 

and the significance of the reduction n1ay then 

be learned by comparing the volume of reduction with the total volume of the current, 

92,000,000,000 cubic feet. As this procedure 

is inconveniently long, I have given the estimates another form by indicating, in separate 

colu1nns, from how 1nany acres of water or of 

marsh in each region the tide may be excluded 

at a cost to the Golden Gate current of its onethousandth part, or the tenth of 1 per cent. 

As regards the open water of the bays, the 

effects of encroachment vary in amount to only 

a moderate extent. It is to be observed, however, that mere remoteness from the Golden 

Gate does not make the effects of encroachnlent unimportant. They are more important for the extreme southern part of San Francisco.Bay than for any other district, and more 

important for the waters between San Pablo 

Strait and Benicia than for the waters about 

the water front of San Francisco and Oakland. 

There is a rapid change in conditions in Suisun 

Bay and in the rivers. For the eastern part 
86 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

of Suisun Bay the effect of encroachment is less 

than at San Francisco, and for the remoter 

parts of the tidal rivers the effect is negative, 

encroachment tending to increase the volume 

in the Golden Gate. (See fig. 14, p. 74.) 

As regards the marshes, all the figures given 

are rough averages, the depth of the effective 

prism varying greatly with details of local condition. It may be said in a general way that 

the tabulated estimates of prism depth should 

be increased for marsh tracts that communicate 

directly with open water and should be diminished for tracts that communicate-only through 

long sloughs. The variation is greatest for the 

delta marshes, those near the mouths of the 

rivers having effective prisms comparable with 

by charts of different dates, showing changes 

in the positions of the outlines of high water. 

and low water. As a rule the water areas 

inclosed by these outlines were greater when 

the early surveys were made than at the dates 

of the later surveys. Changes· of the highwater line have been of appreciable amount 

only where the shore is marshy, and in such 

localities the notation of the charts is not entirely consistent. The marsh edge in natlire 

usually has as one of its features a low beach 

ridge, or else an abrupt change of slope, these 

features being shaped in part by the waves; 

but there are places also where the slope of the 

ground is gradual and uninterrupted, and in 

those the visible limit of the marsh is the outer 

TABLE 24.-Data illustrating, for different parts of the San Francisco Bay system, the relation which encroachments on the 

tidal prism bear to the volume of tidal currents in the Golden Gate. 

Area, in acres, correLocality. 

Depth of effective sponding to one- tenth of 1 per cent tidal prism, in of the tidal volume feet. in the Golden 

Gate. 

Open Marsh Open Marsh 

water. land. water. land. 

Southern l?art of San. F}'~ncisco Bay ............. :: . .................. :. San Francisco and VLCirnty .......................................... . 7.7 1.03 270 2,000 

6.2 1.00 350 2,100 

Northern part of San Francisco Bay .................................. .. 

~~~!R~~e~~~--_': ~ : ~ ~ ~ : ~ ~ : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 

6.05 . 87 360 2,400 

·.7.15 .72 290 2,900 

7.0 .55 300 3,800 

Carquinez Strait ..................................................... . 7.0 .80 300 2,600 

Suisun Bay ........................................................ . 5.'6 .52 370 4,000 

Deltas of Sacramento and San Joaquin rivers ......................... . .6 .02 3,600 100,000 

the prisms of the· Suisun marshes, while large 

areas that communicate with the rivers at 

higher points have negative effective prisms. 

I regard it as entirely possible that the net 

effect of tidal storage in the delta marshes is 

negative inste.ad of being positive, as it appears 

in the table. The ll}eagerness of observational 

data in that region, as well as the recognized 

imperfection of the methods by which the 

marsh prisms were computed, leave much room 

for doubt on this point. On the other hand I 

am confident that the 'total influence of the 

delta marshes on the Golden Gate current, 

whatever its sign, is small, or rather that it was 

formerly small, for· little of this area is now 

accessi}?le to the tides. 

The extent of actual encroachments due to 

deposits of mining and other debris is indicated 

edge of the tract of marsh vegetation. Where 

the beach is present the vegetation may stop 

at the beach or it may follow for a distance 

down the gently sloping strand. It results 

that the high-water line of the charts repre-

. sents in part a beach and in part a limit of 

vegetation. On some of the later charts both 

phases are indicated, with distinctive notation, 

but the distinction is not recognized on the 

earlier charts. The matter is further complicated by the fact that some of the fringing 

plants die down ·in winter, so that the visible 

extent of. the fringe has a seasonal variation. 

The low-water line, the line of .mean lower 

low water, is not surveyed at low water by 

direct observation. Its position is inferred 

from plotted soundings after the soundings 

have been reduced to a common datum by cor-
RELATIONS OF DEBRJS MOVEMENT TO THE GOLDEN GATE BAR. 87 

rections for stage of tide. It represents the 

intersection of the ''plane of ref~rence" with 

the slope of the bottom, and as tha~ slope is 

gentle in the principal regions of deposition 

large errors in the position of the charted line 

n1ay be occasioned by small errors in the plane. 

of reference. There is circumstantial evidence 

that errors of this sort exist (see p. 34), but an 

attmnpt to investigate them encountered difficulty because. 9f in1perfection in the record of 

methods of reducing soundings. On the whole 

the precision of the charted positions of the 

low-water line is believed to be lower than that 

of the position of high water. 

Although these considerations seriously qualify the nu1nerical results that follow they do not 

prism as a weighted mean of the changes in 

high-water and low-water area, assigning to 

the high-water data a weight twice that of 

the low-water data. 

·, Table 25 contains a summary of data and 

estimates of the encroachments on the tidal 

prisms of the several bays. From the amounts 

of change indicated by the charts for the 

periods between surveys the amounts corresponding to the longer period 1849-1914 were 

computed by means of the curve reproduced in 

figure 5 (p. 36). The factors for the conversion 

of aores of encroachment in~o per cent of tidal 

volume are taken from Table 24. 

It will be noted that for a small division of 

San Pablo Bay and for both divisions of 

TADJ,E 25.-Estimates of reduction of tidal currents in the Golden Gate caused by deposition. of mining and o.ther debris on the shoals of the bays. 

Encroachment on Encroach- Area cor- water area shown inent on Encroach- responding ReducPeriod to by charts. tidal prism menton to 0.1 per tion of 

which cent of tidal vol- Bay or division. record (weighted tidal prism tidal vol- umein 

pertains. mean of for period umein Golden High I Lower preced- 1849-1914. Golden Gate. water. low water. ing). Gate. 

Acres. Acres. Acres. Acres. Acres. Per cent. 

s 

s 

uisun Bay ........................ 1867-1886 2,860 2, 280 2, 670 8,330 370 2.25 an Pablo Hay: 

Main body ..................... 1857-1897 2, 160 3, 380' 2,530 3,870 290 1.33 

Southwest of Pinole Point ....... 1857-1900 75 -790 -180 -275 310 -.89 

San Francisco Bay: 

Northern part ................... 1855-1896 40 -500 -140 -220 360 -.61 

Southern part ................... 1858-1898 1, 960 -1,920 670 1,110 270 . 41 

.. 

affect the general inference that the deposits 

have wrought an appreciable and noteworthy 

reduction of the tidal prism. 

In a general way the areal change in the tidal 

prism is equivalent to the mean between the 

change in the high-water area and the change 

in the low-water area, but some exceptional 

conditions are locally so important as to deserve 

n1ention. A shoal tract that appears at low 

water as an island but is submerged by a ~mall 

rise of the tide may change its area· greatly and 

yet affect the tidal prisn1 but little. Such 

ti-acts occur in all the bays, and they are especially abundant· in the southern part of San 

Francisco Bay. By way of allowing for these, 

and at the same time taking account of the 

lower precision of the records of low-water outline, I have computed the change in tidal 

2.49 

San Francisco Bay the charts indicate changes 

of opposite sign for the high-water and lowwater boundaries. They declare that the 

marshes have encro~ched on the open water· 

but that the low-water lines have retreated 

from the open water. Now, if the cause of the 

changes were either deposition, or erosion, or 

subsidence~ or elevation, the probable character of change would be the same for both 

boundaries-that is, the high-water and lowwater lines would both be made to advance or 

else would both be made to retreat. Therefore, as these four categories include all the 

sources of cl?-ange that we need to consider, I 

am prone to believe that the apparent association of advancing high-water lines with retreating low-water lines is not actual and that 

the inconsistency of the results has been 
88 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

occasioned by differences iri method between 

the earlier and later surveys. 

I regard it as probable that on all the shoals 

with which the apparent retreat of the lowwater line is associated there was gr.owth by 

deposition between the surveys of 1855-1858 

and the surveys of 1896-1900, that such subsidence as occurred in the same period had a 

smaller mean amount than the mean depth 

of deposition, and that the negative signs in 

the table represent chiefly errors in the determination of local planes of reference for the 

reduction of soundings. If this opinion is 

warranted the quantitative results for San 

Francisco and San Pablo bays are without 

value. The result for Suisun Bay, however, 

has a much better status, for the reason that 

its two surveys agreed closely in method, and 

also because their methods were better than 

the· methods used in the earlier surveys of the 

lower bays. If the result for Suisun Bay (2~25 

per cent) is substantially correct, the estimate 

of 2.5 per cent as the total loss of tidal current 

occasioned by debris deposits is more likely to 

fall below the fact than above. 

The extent of tide-marsh reclamation is 

.shown in part only by. the charts of the Coast 

Survey and ·the atlas sheets of the Geological 

Survey. From their definite records it appears 

that previous to the year 1912 the marshes 

adjoining San Pablo Bay and Napa River 

were leveed to the extent of 42,000 acres, and 

that previous to 1901 those adjoining San 

Francisco Bay lost 9,600 acres. These abridgments of tidal storage are estimated to have 

reduced the tidal volume in the Golden Gate 

by 0.8 and 0.5 per cent, respectively. A much 

greater acreage has been reclaimed in the delta 

marshes, but the effect on tidal volume is 

believed to be negligible. In recent years the 

reclaimed area south of San Francisco has been 

increased somewhat and there has been much 

activity in the reclamation of the Suisun 

marshes, but as to these works I have no 

statistics. The order of magnitude of the 

effect of tide-marsh reclamation may be indicated by saying that it has reduced the 

volume and velocity of tropic ebb tides in the 

Golden Gate by 1.5 per cent. 

The estimated effect of all debris deposition 

and all marsh-land· reclamation, namely, the 

reduction of tidal volume by 4 per cent, is 

equivalent to the effect· of so extending the 

·water fronts of San Francisco and Oakland as 

to take 14,000 acres, or 22 square miles, from 

the tidal area. 

VELOCITIES. 

The velocity of ·the current by which debris 

is moved along the channel depends chiefly on 

the tidal volume. In strictness the effective 

velocity is that of the strand of current in contact with the channel bed, but it is more convenient to deal with the mean velocity of the 

wh~le .current. Velocity at contact is so difficult of measurement that we have little knowledge of it, and the statements sometimes made 

of its relation to mean velocity are misleading. 

On the other hand, there is a certain amount 

of information as to the relation of mean velocity to the movement of debris. 

The term "mean velocity," as used above, 

denotes the average of v:elocities in a cross section of a ourrent. Its measure is the disoharge 

divided by the area of the section. It is a 

mean with respect to space. The term may 

be used also to denote a mean with respect to 

time. In the movement of tide water through 

a particular section during the period from one 

slack to the next, the velocity is variable, first 

increasing from zero to "strength '' . and then 

diminishing from strength to zero. The mean 

velocity for the tidal period is less than the 

velocity "at strength," and the approximate 

ratio between the two is that of 2 to 1r.1 The 

measure of the mean mean velocity, or the mean 

velocity with .respect to both time and space, 

at any section is the tidal volume divided by 

the area of the section and by the length of 

the tidal period. The velocity to be considered in relation to movement of debris is 

the mes.n as regards space and the maximum 

as regards time and is computed by multiplying the mean mean velocity by ?r/2. 

. The velocities in the Golden Gate associated 

with mean tide and with the great tropic ebb 

tide have been computed and are reported in 

Table 26. In the same table are velocities 

attributed to a very large tide, the great ebb 

of December 16, 1914. The predicted range 

of that tide was 8.5 feet, and it was a matter 

of observation that the water rose higher on 

that day than on any other day of the year. 

The tidal volume corresponding to that range, 

1 This is the theoretic ratio of mean to strength under mean-tide conditions, when the velocity curve is a sine curve and symmetric. It is 

only approximate for the velocities associated with tropic tides. 
. RELATIONS OF DEBRIS MOVEMENT TO THE GOLDEN GATE BAR. 89 

computed by the formula 01i page 82, is 

134,400,000,000 cubic feet. · 

In addition to the computed values of mean 

velocity "at strength," the table contains a 

few estimates of the midstream surface velocity. This is greater than the mean for the 

section, the ratio between the two depending 

on the character of the bed and walls of the 

channel. For the narrowest part of the 

Golden Gate the ratio assumed is 133 to 100. 

Clapp, Murphy, and Martin/ who studied a . 

great flood in 1907, estimated that if ~ts waters -

had gone unimpeded to the bays the mean rate 

of delivery for four days would have been about 

782,000 cubic feet per second; and a closely related estimate has been made from the same 

data by the California Debris Commission, 

which is charged with the construction of works 

for control. All authorities are agreed, however, that such ·a rate of delivery has not been 

TABLE 26.- Velocities of ebb currents at the time of greatest strength, with associated data. 

Place. Year. Designation 

of cmrent. 

Golden Gate at Fort Point ........ 1856 Mean tide .... ])o ........... -............... 1856 Great tropic .. Do ........................... 1914 Dec. 16 ..••.. 

Midslot>e (inside) of bar ....... , ..... 1900 Great tropic .. Crest of bar ....................... 1900 ... .. do ....... 

San Pablo Strait ................... 1856 . .... do ....... Do ........................... 1879 . . . . . do ....... 

Pinole Shoal. ...................... 1856 ..... do ....... Do ......................•.... 1897 ..... do ....... 

Car))~~~~-~~~~i~-~~ :.~~t- ~i-1~~~: ~: 1856 ..... do ....... 1886 ..... do ....... 

The water that enters the bays from streams 

n.nd falls on their surface as rain escapes by way 

of the Golden Gate, except for a fraction absorbed by the air. Flowing outward through 

the strait, it increases the ebb velocities .and 

di1uinishes the flood velocities. The mean volume of river water is so small compared to the 

tidal volumes that its influence on velocities is 

negligible, but the volume from flooded streams 

is of importance. 

There are no adequate measurements of the 

rate of delivery of flood water t9 Suisun Bay by 

the rivers, either at the present time or in the 

earlier times when the movements of river 

waters were not obstructed by levees. Continuous measurements, however, are made of 

the discharge of streams near the points where 

they enter the Great Valley, and the data from 

these measurements have been used in estimating the ma..-x:imum flood discharge to the 

bays after the completion of the system of 

works under construction for flood control. 

Duration I 

Velocity. 

Volume of Area of 

cur!ent. of ebb. section. Mean for Maximum 

section. surface. 

Gu.ft.X106 Seconds. Square feet. Ft.fsec. Ft.fsec. 52,552 24,360 912,400 3.7 5.0 

91, 948 30,600 909, 800 5.2 6.9 

134,400 32,220 907,600 7.2 9.6 

f93, 000] f30, 360~ 1,514,000 3.2 ............ 94,000] 30, 120 2, 380,000 2. 1 .............. 

40,800 25, 680 497,000 5.0 .............. 29, 200 25, 680 494,000 4.9 ............. 

23. 940 26, 130 . 340,000 3.9 .................. [19; 200] 26, 130 283,000 4.1 .............. 

20, 580 26, 580 234,000 5.2 ................... [18, 400] 26, 580 198,000 5.5 .................. 

realized in the past, and before the construction 

of levees it was not even approached. So much 

flood :water was stored in the lateral basins of 

Sacramento Valley and on the delta marshes 

that the delivery to the bays was regulated as 

by a reservoir. Its rate may never have exceeded 300,000 cubic feet per second, and 

400,000 cubic feet can be accepted as an outside 

estimate. · 

A discharge through Golden Gate of 400,000 

cubic feet per second corresponds to a mean 

velocity; at the point ·where the section is least, 

of 0.435 foot per second and to a midstream 

surface velocity of 0.58 foot per second. This 

is not a large fraction even of 5 feet per second, 

the average midstream velocity for all tides, 

but is nevertheless of importance because of the 

great addition to power of transportation which 

accompanies a moderate increase of velocity. 

An estimate of maxi.mum midstream ebb velocity in the strait may be obtained by adding 

1 Am. Soc. Civil Eng. Trans., vol. 61, pp. 281-330, 373-376, 1908. 

I 
90 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

the estimated maximum velocity from river so the characteristic material of the bed at any 

flood to the estimated velocity on December 16, point is an in4ex of the local velocity of the 

1914. The sum is 10.2 feet per second, which current. 

equals 6.9 miles per hour. The late Prof. Because of this general correlation between 

George Davidson 1 says: "Between Fort Point velocity and the texture of bed material, 

and Lime Point we have measured the ebb sur- I have been led to compare certain of the 

face current running with a velocity of 6.6 miles velocities listed in Table 24 with samples 

per hour, whilst the subsurface current8 have from the channel bed at the same places. 

been measured running over 8 miles per hour." Each of the velocities used in the comparison 

Velocities on the bar-mean velocities at is the mean velocity, within a particular section 

strength of current for tropic ebb tides-have of channel, at the time of the greatest strength 

been computed for the inner slope, halfway of an average tropic ebb current. The mode 

from the headlands to. the outer crest (see of comparison assumes a constant ratio befig. 10, p. 70), and for the crest itself. In tween this mean velocity and· the greatest 

making the computations the tidal volume and velocity on the bed in the same section, and the 

tidal period, which are not accurately known, result of the comparison is qualified by the 

were assumed to be the same as at Fort Point, inaccuracy of this assumption. 

and assumptions were involved also in the Most of the available specimens of bed rna-

. determination of sectional areas. The section terial from the localities for· which velocities 

lines selected were curves, resting at the south have been determined· are samples brought up 

against Ocean Beach and stopping northward by the sounding lead: They were obtained by 

at the outer edge of the Bonita Channel, which ·the United States Coast and Geodetic Survey 

is said to carry little or none of the ebb current; in connection with its hydrographic work and 

and no allowance was made for the fact that are now preserved in the United States Nathe probable direction of the current is not tional Museum. For some of the velocity staeverywhere normal to either assumed line of tions the collection includes several samples, 

section. · On the whole the estimates of mean and from each such set of samples the coarsest 

velocity are more likely to be too small than was chosen for the comparison. Each selected 

too large. sample was divided by means of sieves into 

a series of grades, and the grade found to conCOMPARISON OF VELOCITIES WITH THE CHARACTER OF THE D£BRIS IN TRANSIT.. t~in the largest fraction of the sample was taken 

The velocity wit_h which a current sweeps its 

bed varies from point to point of the bed. It 

is controlled not only by those conditions which 

determine mean velocity but by bends and 

other details of the shape of the channel. The 

debris transported by a current usually includes 

particles ·of diverse size, the range from largest 

to smallest being great, and usually a portion 

of the load-the finer portion-is borne in 

suspension, while the remainder is dragged 

along the bed. The line of separation between 

suspended load and bed load is drawn by 

velocity, the suspended load being larger and 

including coarser debris as the velocity is 

greater, so that the constitution of suspended 

load and of bed load changes with changes of 

velocity. The debris which composes the bed 

at any point belongs to the bed load (except 

as finer stuff may lodge in its interstices), and 

1 Pacific Coast Pilot, 1889 ed., p. 227. As the Coast Pilot is written for 

navigators, it is possible that the "miles" referred to are nautical. A 

velocity of 10.2 feet per second equals 5.9 nautical miles per hour. 

to represent the sample. The corresponding 

mean diameter of debris particle was then obtained from a table prepared in connection 

with the Berkeley experiments on debris transportation.1 

The mean diameters, representing the grade 

of bottom material in respect to coarseness 

were then plotted in relation to the associated 

mean velocities, the plot being made on logarithmic section paper. · The data gave five 

plotted points, and it was found that four of 

these lay nearly in line, the fifth being rather 

aberrant. The equation given by the four 

points i~ 

D=0.093 v1.6 

in which D is mean. diameter, in millimeters, 

an•d V is mean velocity, in feet per second. 

By means of this equation a value of D was 

computed for each velocity; and in Table 27 

the computed and observed. values are assembled for comparison. 

1 See U. S. Geol. Survey Prof. Paper SG, p. 21, 1914. 
RELATIONS OF DEBP.JS MOVEMENT TO THE GOLDEN GATE BAR. 91 

TABLE 27.-Co~pamon ,of velocities of tropic ebb current 

at strength, 1.mth coa:seness of debris constituting channel 

bed, the. coar_seness bmng rep_r.e~ented ~y the average diameter 

of partwle ~n the charact~t~c portwn of the debris. 

Average diameter 

of particle. 

Locality. Velocity. 

Com- Observed. puted. 

Feet·per .Milli- }.{illiCrest of bar, San Fran- second. meters. meters. 

cisco entrance ....... 2.1 0.30 0.2 

Midslope d.inside) of bar. 3.2 . 56 . 65 

Golden ate at Fort 

Point ............... 5.2 1. 30 1.3 

San Pablo Strait ....... 4. 6 1. 07 [0. 6-0. 8] 

Pinole Shoal. .......... 3.6 . 72 . 2 

Carquinez Strait ....... 5.2 1. 30 1.3 

·The more accordant diameters are those for 

the inner slope of the bar, for the Golden Gate, 

and for Carquinez Strait. For San Pablo 

Strait the tabulated diameter was not determined from a preserved sample, but its value 

was inferred from descriptions of samples recorded by the surveyor. The value is materially less than that appropriate to the velocity. 

It is not surprising that there should be discOI·dance for the crest of the bar, because there 

the conditions are peculiar. Wave aO'itation • 0 

1s added to current action as a sorting agency; 

and the sand that reaches the crest by rolling 

and tumbling along the bottom can esc.ape 

fron1 it only when trituration has fitted it for 

suspension. 

For Pinole Shoal the discordance is great. 

It is in fact much greater than appears from 

the contrast of the tabulated diameters-0. 72 

millimeter as computed and 0.2 millimeter as 

observed-for on ·the bed of the channel at 

that point the characteristic material is an impalpabl? mud, and the sand affording the meas-

·urement of diameter is only a minor constituent. Not only the mud but the greater part 

of the sand is so fine as to be carried in sus-

})ension by the stronger ci.rrrents of the locality, 

an~ the fact that such material occupies the 

entire bed of the channel is one requiring explanation. It appears to me probable that 

th~ peculiar condition is occasioned by flocculatiOn. Where muddy river water meets .and 

n1ingles with sea water the salt usually causes 

the suspended particles to gather together in 

fleecy bunches, or floccules, and these sink 

through the water more rapidly than individual particles, so that their formation tends to 

carry the suspended matter to the bottom. 

At ordinary stages· of Sacramento and San 

Joaquin rivers their waters meet the sea salt 

ne~r their mouths 1 and the resulting precipitatiOn may affect chiefly the shoals of Suisun 

Bay, but at ~imes of great flood, which are also 

the times of greatest suspended load, the chief 

mingling of waters is probably in the upper 

end of San Pablo Bay, and it may be supposed 

that the resulting flocculation enables a larO'e 0 

amount of suspended mud to reach the bottom.- Accordant with this supposition is the 

fact that the layer of mud which was spread 

over the great northern shoal of San Pablo 

Bay between 1856 and 1896 was much thicker 

near Carquinez Strait tha~ farther west. · If 

this view is well founded, the line of separation 

of transpotted debris into· suspended load and 

bed load is not here a simple function of coarseness of debris particles and velocity of current 

but is materially influenced by the tendency 

of the particles to adhere. It is conceivable 

that the floccules on reaching the bottom become units of the bed load and are rolled by 

the current, but it appears to me more probable 

that the same property of surface tension which 

determines flocculation serves also to weld the 

pa.rticles of the channel bed into a coherent 

mass which resists the scouring force of the 

current. 

SOURCES OF BAR MATERIAL. 

There is no question that a large part of the 

debris constituting the bar has been quarried 

by the waves from the cliffs of the outer coast. 

A smaller part must have been derived from 

shore cliffs bordering the Golden Ga to. Some 

may have been furnished by the few cliffs of 

the bay shores, but the contribution from these 

would in any case be inconsiderable. Finally, 

a portion may have come from Sacramento and. 

San Joaquin rivers. The body of sand delivered to Suisun Bay by the rivers has been 

great, and the present annual contribution is 

evidently large, but there is room for doubt as 

to· the delivery of river sand on the bar. The 

pres~nt section is concerned with the question 

1 At low stages of San Joaquin River the flood tide is said to carry 

brackish water several miles above its mouth .. In Carquinez Strait the 

ordinary salinity, according to tlie Albatross observations, is about one 

half that of the ocean.· 
92 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

whether or in what quantity river sand finds its 

way to the bar, and the discussion deals particularly with the evidence afforded by samples of 

sand from various localities. Sand from the 

surface of the bar is compared with sand from 

neighboring beaches of the outer coast and the 

Golden Gate and with river sand. 

In connection with an elaborate mapping of 

the bar in 1873 a series of bottom samples were 

obtained by the United States Coast and Geodetic Survey. They came from more than 100 

points and represent the whole surface of the 

bar. They range from fine sand to small 

gravel, and with some of them are broken shells 

as well as a few ~m~ire shells. The sands are 

clean, in the sense that they hold no mud, and 

the range of size in each sample is less than is 

usually found in river sand. The characteristic or dominant diameter of grain on the crest 

of the bar is in some places as low as 0.13 millimeter, in others as high as 0.25 millimeter; the 

average is 0.20 millimeter. The sand of the 

outer slope, sampled only to a depth of 10 · 

fathoms, appears similar to that of the crest. 

On the inner slope there is a general increase in 

coarseness with increase of depth, the characteristic diameter at 20 fathoms being about 1 

niillimeter. 

The sand samples to represent the supply 

from local sources were obtained from Tennessee Cove and Rodeo Beach, north of Point 

Bonita, from Ocean Beach, and from a beach 

between Point Lobos and Fort Point. 

The river sands selected for comparison were 

not taken from the river beds but from the bed 

of the main tide channel through Suisun Bay, 

Carquinez Strait, and San Pablo Bay. That 

channel, which was remodeled and contracted 

by the invading debris from the mines, is 

unquestionably lined by sand and gravel from 

the rivers, and the material of its bed epitomizes the composition of sands from the two 

rivers and their tributaries. The Suisun and 

Carquinez samples were obtained by the Coast 

Survey during the hydrographic surveys of the 

year 1886, being brought from the bottom by 

the sounding lead. The San Pablo samples 

were collected in 1913 by the United States 

Bureau of Fisheries, in connection with a biologic survey of the waters of the bays that was 

undertaken in cooperation with the University 

of California.1 In that work the steamer Albatross was employed, and samples of the bottom 

were taken by means of a special apparatus 

which penetrated the deposits to a depth of 

several feet, bringing up a core. Two such. 

cores were obtained from the same station in 

San Pablo Channel, at a locality within the 

tract known to navigators as Pinole Shoal. 

From one of the cores three samples were 

taken-the top, middle, and bottom partsand were examined under the direction of Prof. 

George D. Louderback. Three similar samples 

from the other or duplicate core were. lent to 

me for examination. Louderback's report 2 

includes the following information: 

The core obtained January 13, 1913, at 

hydrographic station 5288 had a length of 117 

centimeters (3.8 feet). The inorganic material 

of the three samples was composed as follows: 

Diameter of grains. Top. Middle. Bottom. 

Percent. Percent. Percent. 

Less than 0.02 millimeter ...... 93. 70 70.61 56.27 

From 0.02 millimeter to 2.0 

millimeters ................ 6.30 29.28 43. 73 

From 2.0 to 5.0 millimeters .... .............. .11 . ............. 

100. 00 1100. 00 100.00 

A mechanical analy$is of samples from the 

duplicate core gave: 

Diameter of grains. Top. Middle. Bottom. 

Percent. Percent. Percent. 

Less than 0. 02 millimeter ...... 88.5 65.6 57.1 

From 0.02 to 0.06 millimeter ... 5.5 8. 7 4.5 

From 0.06 to 0.15 millimeter ... .9 1.9 2.6 

From 0.15 to 0.2 millimeter .... 2.4 8.2 13.4 

From 0.2 to 0.3 millimeter ..... 1.6 8.0 14.5 

From 0.3 to 0.4 millimeter ..... 1.1 7.0 7.1 

More than 0.4 millimeter ...... ............. . 6 .8 

100.0 100.0 100.0 

The results of the two analyses are in substantial agreement. The material which the 

analysis of the first core reports as larger than 

2 millimeters consists of thin flakes of shell and 

I The first publication resulting from the work of this survey is "A 

report upon the physical conditions in San Francisco Bay, based upon 

the operations of the U.S. Bureau of Fisheries steamer Albatross during 

the years 1912 and 1913," and constitutes vol. 14, No. 1, of University of 

California Publications in Zoology,1914. 

z.Idem, pp. 14-19, 175-192. 
RELATIONS OF DEBRIS MOVEMENT TO THE GOLDEN GATE BAR. 93 

mica, as easily transported as the coarser material of the duplicate core. 

The greater· detail of the second analysis 

brings out the fact that the curve of size for 

the debris has two maxima, and this feature, by 

indicating that the deposit is a mixture of two 

materials of very different coarseness, supports 

the hypothesis of flocculation. One material, 

of which the characteristic diameter lies between 0.15 and 0.3 millimeter reached the place 

as bed load, drifting along the bottom of the 

channel. The other, of which the characteris-

. tic diameter is less than 0.02 millimeter, was 

deposited by flocculation from the suspended 

load. 

[Since the preceding paragraph was written 

I have had further opportunity to examine the 

Albatross samples and have learned that the 

Pinole shoal deposits are distinctly laminated. 

Alternating thin layers are characterized by 

coarser and finer materials, corresponding to 

the two grades revealed by the analysis. The 

layers containing the coarser grains carry also 

some of the finer and may be called fine, muddy 

sand; the intervening layers are of pure mud.] 

The position of the Albatross when the cores 

were taken is recorded by bearings and when 

plotted appears to be at the edge of the artificial channel maintained by dredging across 

Pinole Shoal. (Seep. 102, footnote.) Therecorded depth of water indicates that it is within 

the area of excavation. A comparison of the 

records of sounding at various dates with the 

record of dredging operations has made it 

seem highly probable that the lower parts of 

the cores are from a deposit of earlier date 

than 1856, in which case they represent the 

alluvium traversing the cha1mel before the 

flow of mining debris. This inference finds 

support in the fact that the sandy portion of 

the core material is notably distinct from the 

sand occurring in Carquinez Strait in 1886, 

which represents post-mining debris. The 

n1aterial of the upper parts of the cores may be 

a fresh deposit washed from the side of the excavated channel, but it is distinguished from 

the material of the lower parts only by the 

relatively large proportion of mud. 

In a preliminary examination o{ the sands 

with reference to composition it Wa$ found that 

the proportions of different components are not 

the same for the coarser and finer parts of the 

same sample, and because of this fact the portions to be subjected to fuller comparison were 

separated by sieves so as to have about the 

same mean diameter, 0.2 millimeter. 

in general color the sands show certain differences. The following statement does not attempt to describe the colors but refers only to 

differences: All sands from the bar have about 

the same shade. Sands from beaches near the 

bar agree in color with bar sands but are 

slightly darker. When sands from Suisun and 

Carquinez channels (river sands, 1886) are compared with bar sands the former appear relatively orange and the latter relatively greenish . 

When the Suisun and Carquinez sands are com~ 

pared with sand from the San Pablo channel (Albatross sample) the former appear relatively orange and the latter relatively green. 

When the San Pablo sand is compared with bar 

sand the former appears gray and the latterbrownish. 

In all the s'ands the most abundant material 

is quartz, 1 and some of the quartz is clear and 

vitreous. Much of the quartz is colored, the 

coloring matter being either diffused 1 or in 

specks. The colors of the quartz produce most 

of the differences in the general colors of samples. Few grains of feldspar were recognized, 

but no serious attempt was made to discriminate feldspar from quartz. Among the dark 

grains only a few seem to be fragments of crystals, but such occurrences are rarer in the bar 

sands and beach sands than in the river sands. 

In all the sands the dark grains are chiefly rock 

fragments, each being an aggregate of two or 

more minerals, and the dominant mode of aggregation is that of holocrystalline igneous 

rocks. 

The inquiry was directed especially to the 

'discovery of some material at the same time 

fairly abundant in the river sands and very 

rare in beach sands· of the coast, so that its 

occurrence in or absence from the bar sand 

might lead to inference as to the presence or 

absence of river sand in the bar, but no such 

material was found. All the chief components 

of the river sands occur also in the beach sands. 

On the other hand, there is a prominent component of the beach sands which was not found 

in tlie river sands. This is quartz from the 

radiolarian cherts of the Franciscan formation. 

Much of it is strongly colored, reddish brown or 

l This appearance was observed \Vith a microscope or low power; high 

power was not applied. 
94 HYDRAULIC-MINING DEBRIS IN THE SIER.RA NEVADA. 

green, and it has a distinctive structure. It is 

conspicuous not only in the beach sands but 

also in the bar sands, but its presence on the 

bar serves only to confirm tne inference from 

the physiography that the· bar is built· chiefly 

of the waste from coastal cliffs. 

The sand from the San Pablo channel is distinguished from all the other sands, including the river sand of Carquinez Strait and 

Suisun Bay, by the ~act that it contains almost 

no yellow quartz grains or quartz grains with 

yellow specks. This peculiarity conforms to 

the inference, drawn from other data, that the 

core samples represent debris brought to the 

bays by the rivers before the time of hydraulic 

mining. 

In all the sands large· grains are, as a class, 

better rounded than small, and dark grains are 

better rounded than pale. Of the small grains, 

0.1 to 0.3 millimeter ;in diameter, very few are 

worn to pebble form except in the bar sands. 

The edges of angular grains show more rounding in the bar samples than in any other. 

Edges that show no evidence of wear are rarely 

seen except on grains of transparent quartz. 

They ·occur on such grains in all the samples, 

but least commonly in the samples from the 

bar. 

The evidence of the sand samples is supplemented by data from the dredging operations 

on Pinole Shoal. On the line of the artificial 

channel the dredge has removed all the debris 

deposited in the natural channel since the year 

of the first general survey, 1856, and has penetrated several feet into the earlier or premining deposit. I am informed by Capt. H. L. 

Demeritt, the engineer in immediate charge of 

the work, that all the dredged material would. 

be classed by dredgers as blue mud -it is so 

coherent as to "stand up'' on the dredge 

bucket like stiff mud or clay-but that a magnifying glass shows that it contains much fine 

gray sand. This description applies perfectly 

to the material of the core samples and gives 

generality to certain inferences from the samples. The coarser river-borne material finds the 

limit of its journey where the current slackens 

between Carquinez Strait and Pinole Shoal, and 

the same limit existed in pre-mining times. 

Nothing coarser than fine sand gets beyond 

Pinole Shoal. The coarse sand and fine gravel 

moving down Sacramento River is reduced by 

attrition before it reaches San Pablo Bay. 

It does not necessarily follow that the river 

debris makes no contribution to the bar, for the 

sand found in the core samples from Pinole 

Shoal is not too fine to come to rest on the bar 

and it is constituted of grains which by surviving have demonstrated great ability to 

stand buffeting. The comminution of debris 

by rolling and jostling on a stream bed is a 

process which becomes less rapid as coarseness 

is reduced. The weaker grains tend to disappear, being ground so fine as to join the 

suspended load, and the surviving resistant 

small grains suffer little from the feeble blows 

they give one another. So the rate of wear 

from Pinole Shoal to the bar is less than the 

rate from the river mouths to Pinole Shoal. 

There must, however, be some wearing, and as 

the sand grains at the shoal are already about 

as small as those on the crest of the bar only a 

little wearing is needed to unfit them for deposition on the bar. About 92 per cent of the 

grains on Pinole Shoal are either rounded or 

else have edges blunted by attrition, and as 

they are shown by that fact to be destructible 

it seems fair to assume that they will not survive the long journey. Of the remaining 8 per 

cent, grains of vitreous 'quartz with sharp 

edges, a portion may reach the bar. As the 

sand of Pinole Shoal is itself but a remnant of 

the bed load of the rivers, it would appear that 

the possible contribution, past or present, 

made by the riyers to the bar is but a minute 

fraction of the great body of mining debris and 

soil waste, while the probable contribution is of 

no practical importance as a factor affecting 

the history of the bar. 

OBSERVED CHANGES IN THE BAR. 

In 1881 Lieut. Col. G. H. Mendell 1 made a 

report to the Chief of Engineers, United States 

Army, on causes tending to decrease the depth 

of water on the bar. ·The report contains an 

admirable statement of the general situation 

at that time, draws such conclusions as were 

warranted by the data then available, and 

points out the lines of investigation which 

would lead to more definite and satisfactory 

conclusions. From a comparison of the charted 

results of two surveys, made by the Coast Survey. in 1855· and 1873, he infers that the changes 

which took place in the .intervening 18 years 

were not great and that the 'depth of water on 

1 Chief Eng. U.S. Army Ann. Rept. for 1881, pp. 2515-2524. 
RELATIONS OF DEBRIS MOVEMENT TO THE GOLDEN GATE BAR •. 95 

the crest·of the bar was, if anything, greater at In. the vicinity of that contour the inner slope 

the time of the second survey, but he also moved oceanward through a space of more 

states that the first survey was not sufficiently than 1,000 feet. So the great body of sand to 

elaborate to make the comparison entirely which the name bar, ~ its larger sense, is 

satisfactory. Three years later Prof. George applied became notably narrower near its base. 

Davidson 1 addressed the Geographical Society The ch~rts do not cover the entire body but 

of the Pacific on the same subject, and he also perhaps nine-tenths of it-a tract of about 44 

presented the rest1;lts of a comparison of charts, square miles. From th~.t tract the average 

his conclusions agreeing with those of Col. Men- vertical loss was 1. 7 feet, corresponding to a 

dell. More recently a graphic 4iscussio:r: by volume loss of 77,000,000 cubic yards. 

Nautical Expert' J. T. Wilkins, of the Coast These.changes were accompanied·by a change 

Survey (see Appendix C), took account of .a in the position of the 'crest line. In the medial 

change. which had been made in the "plane of region, where the summit is narrowest and the 

reference," or zero of soundings, between the crest best defined, its migration was measured 

dates of the two surveys, and it appeared that from 1855 to 1873 and from 1873 to 1900. In 

when the proper correction for tllis change had each interval the migration was toward the 

been applied the earlier conclusions as to depth land. The distance traversed during the first 

were not sustained; the &verage depth on the interval of 18 years is not very definitely 

crest of the bar was notably less in 1873 than in shown but falls between 400 and 700 feet; dur1855. Both Mendell and Davidson recom- ing the second interval, of 27 years, it falls 

mended that a new survey be made, the data between 400 and 500 feet. The average annual 

fr01n which could be compared with those from rate, which was greater for the first interval 

the survey of 1873, and that yet other surveys than for the second, was 20 to 25 feet for the 

be made from time to time. In 1884 a few whole period of. 45 years. The total change in 

lines of soundings were run, and in 1900 there tliat period was from 3 to 3.5 per cent of the 

was a complete resurvey, coordinate with that whole distance of that· portion of the bar crest 

of 1873. 'from the generallip.e of the coast. 

I have carefully .. c.ompared. t4e sou,nding _ The corre~tiqn that Watkins applied in his 

records of 1900 with those of 18.73~ ·in~killg_'{i~e .:discussion ·of the relative crest heights in 1855 

of . the large-scale manuscript charts in the and 1873 is ·equally applicable to other parts 

archives of the Coast Survey, which contain of the bar. The combination of his results 

much fuller data than the published charts, with those of Mendell and Davidson yields as 

and receiving, through the courtesy of that its broadest generalization a general growth of 

Survey, the advice and assistance of cert·ain of the ba~ between those dates. ·so the conits experts. As the full record of the com- elusions that appear to follow from the data 

parison involves :many details it has been rele- given by the three surveys· are (1) that the 

gated to an appendix (pp. 139-148) and only volume of the bar increased between 1855 and 

the general results will here be given. 1873; (2) that the volume of the bar diminished 

Between 1873 an9. 1900 the crest of the bar between 1873 ~nd 1900; and (3) that the crest 

was lowered through most of its length, the of the bar moved toward the land during both 

average amount being 0.9 foot. This change of these periods. 

was least in the medial or western third of the As to the validity of these results, it may be 

bar and greatest in the southern third, where said that those involving data from the sw·vey 

the· bar summit is expanded into a broad, of 1855 are less secure than those dependent 

plateau-like shoal. , There was a loss of several only on the later surveys. ·It is my judgment 

feet from the outer slope of the bar, a change also that those relating to the· migration of the 

which may be otherwise stated by saying that crest are more secure than those relating to the 

the outer slope 1noved landward through a dis- ·volume or general height of the bar. 

tance of several hundred feet. There was also 

a loss from the inner slope, relatively s;m.all INTERPRETATION OF OBSERVED CHANGES. 

near the crest but increasing with depth until The San Francisco bar is so unlike other harat the 16-fathom contour it amounted to 8 feet. bor bars that a comparative study throws lit1 'l'bo shoaling of tho bar at tho entrance to San Francisco Harbor: 

Ooog. Soc. Pacific Proc.,·mootlng of May 20, 1884, pp. 2-23. 

71139°-17-7 

tle light on its hydraulics. With the aid of the . 

United States Hydrographic Office I have 
96 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

sought its nearest relatives, finding them in 

the submerged delta of the Tagus, outside Lisbon Harbor, and in the tide-built bar outside 

Manukau Harbor, New Zealand; but I have 

failed to correlate the differences of form with 

recognized differences in local conditions. 

On the shore of Evolution Lake, an alpine 

lake in the Sierra Nevada, I once saw miniature bars that copied the outline of the bar at 

San Francisco. The shore there was straight 

and bore at the water's edge a steep, narrow 

parapet of sand that had been crowded up by 

the ice in winter. The water from a recent 

storm gathering behind the parapet had 

a gentle inclination seaward. They grade the 

surface by removing prominences and filling 

hollows. In what might be called the Franciscan Bight, from Duxbury Point to San Pedro 

Point, the general slope is at the rate of 1 in 

700 but becomes steeper as the beach is approached. The bar, which has outward slopes 

of 1 in 150 to 1 in 100, rises above this platform 

as if built on it and constitutes a prominence 

such as the normal action of the waves would 

remove. It would be a mistake, however, to 

think of the bar as resting on the platform. 

Bar and platform have been developed together, the waves molding the outer face of 

FIGURE 20.-Miniature sand bar in Evolution Lake, Sierra Nevada, illustrating the mode of origin of the Golden Gate bar. From a photograph 

by W. D. Johnson. 

breached it at several points, and at each 

point the sand washed from the parapet had 

b'een deposited in the lake as a semicircular bar. 

(See fig. 20.) The outrush of water was strong 

and brief and the supply of sand was local and 

small. The phenomenon serves to indicate 

that the semicircular form is normal where the 

depositing agent is a strong current reaching 

still water through a narrow passage. It is 

probable, therefore, that the general form of 

the San Francisco bar has been given by the 

tidal currents and that the cooperation of the 

waves is not essential to its production. 

It is a generalization from the features of 

many coasts that the waves, when acting on 

an inshore bottom of loose material, give to it 

the bar at the same time that they molded the 

platform. 

Three principal factors go to the determination of the form of the bar-the tidal currents, 

the waves, and the supply of sand. 

In the Golden Gate, as in the bays, the ebb 

currents develop higher velocities than the 

flood currents and thereby determine the 

movement of debris outward. The chief conditions on which this dominance of the ebb 

depends do not necessarily continue to the 

bar, but another condition is there added. 

Bonita Channel carries very little of the outgoing tide but carries a large volume of the incoming tide, and by consequence the average 

ebb volume crossing the bar is greater than 
RBLATIONS OF DEBRIS MOVEMENT TO THE GOLDEN GATE BAR. 97 

the average flood volume. It is therefore 

probable that the tidal currents move sand 

outward all· the way to the bar crest and 

would if unopposed deposit it just outside the 

crest. After passing the crest the ebb current 

slackens because its depth increases, and it 

slackens especially at ·the bottom because of 

its tendency to leave the bottom. and pass 

oceanward as a surface current. 

Wave work as an agency for molding the 

bottom results from a to-and-fro motion of 

the water .in contact with the bottom, in conjunction with whatever motion the same water 

may have as part of a current. The to-and-fro 

motion may of itself be relatively swift in one 

direction an<l thereby transport sand; and by 

lifting sand momentarily from the bottom it 

enables currents, even very feeble currents, to 

perform the work of ·transportation. It is 

tlll'ough such action as this that the outer 

slope of the bar receives its profile, a profile 

slightly concave except near ·the crest. I have 

no knowledge <?f the interactions by which this 

profue is determined but am confident that it 

is in fact a profile of equilibrium, so that when 

any pru·t of it is disturbed by some extraneous 

cause the reestablishment of eqllilibrium involves the reconstruction of the whole profile. 

When the crest of the bar was moved landward, as shown by the surveys of 1873 and 

1900, the whole outer profile (clown to the 

10-fathom contour, which, limits the area of 

comparative data) moved in the same direction: 

The magnitude of the to-and-fro motion and 

the consequent strength of wave action vary 

inversely with depth. On the outer face of the 

bar the action is so feeble at 12 fathoms as to 

allow mud to come, to rest, but at all soundings in less depth the .material of the bed is 

reported to be sand. The action reaches its 

1naximum a~ the bar crest, where the reaction 

is so strong that the largest waves are made to 

break at the surface. In the act of breaking 

they are changed wholly or partly to waves of 

another type, and as these move on landward 

they have less energy. · 

Despite the incompleteness of this analysis, 

it serves to show that of the two molding agencies the tidal currents dominate inside the 

crest and the waves outside. The region of the 

crest is their common ground, and I believe it 

to be their field of conflict. As the ebb current has caused the advanced position of the 

bar, I think of it as striving ever to push the 

crest farther out. As the waves have, within 

the period of observation, pushed back the 

central part of ·the bar, I think of them as 

striving ever to force it toward the land. 

Postulating that the strength of the windmade waves, though highly variable in detail, 

is in long averages constant, and knowing the 

average strength of tidal currents to be dependent on the volume of the tidal prism, I 

infer that the position of the ·bar may be 

changed by any influence affecting the tidal 

prism. 

Tidal discharge (proportional to tidal volume) 

is measured by the product of width of channel 

by mean depth of channel by mean velocity. 

Adapting this formula to the matter under 

consideration, we. may say that tidal volume 

is approximately proportional to the length of 

the bar (corresponding to width of channel), 

to the depth of water on the bar, and to ebb 

velocity across the bar. A reduction of tidal 

volume first affects velocity; reduction of 

velocity causes the bar crest to retreat landward; the retreat shortens the bar; and the 

shortening of the bar, by diminishing the 

channel space, tends to restore the velocity. 

In the final !eadjustment to equilibrium with 

wave action the bar is shorter and nearer shore. 

This statement, however, is incomplete because the shortening of the bar affects other 

dimensions of the bar ap.cl affects also the 

relation of sand supply to sand waste. To 

appreciate the importance of these additional 

reactions it is necessary to give attention to 

the process of sand wasting, which is a factor 

coordinate with wave molding a:r;1d current 

molding in the control of the bar. 

The sand that is fed to the bar tmough the 

.erosion of coastal cliffs wo~d steadily augment 

the volume of the bar if there were no process 

of removal. The removal is accomplished by 

trituration and suspension. Moved by waves 

and currents, the grains strike one another 

and are worn smaller, and the currents finally 

bear away in suspension not only the minute· 

chips stricken off but the reduced grains. 

The work is probably most active in the 

region of the bar crest, where the wave effect 

is strongest, and the quantity of sand thus 

worn out and removed is, other things being 

equal, proportional to the length of the bar. 

The quantity is also related to the velocity of 
98 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

the ebh current, which is the vehicle of the 

deported grains, for that velocity determines 

the critical size that separates the grains to 

remain from the grains to float away. With a 

weaker current the grains remain longer in the 

field of trituration, and so the wasting is 

slower; with a stronger current the wasting is 

more rapid. 

We return now to the subject of the shortening of the bar as a consequence of a reduction 

of the tidal. prism. Let us assume, for the 

moment, that the shortening is accompanied 

by proportional reduction of all other horizontal dimensions but that the volume of the 

bar is unchanged. It follows that horizontal 

shrinkage is accompanied by vertical expansion, the fractional increase 'in height being 

equal to the fractional decrease in area, or 

(approximately) to twice the fractional reduction of the crest in length. If the length is 

reduced by 1 per cent, for example, the height 

is increased by 2 per cent. In the central part 

of the bar the height of the crest above the 

general plane of the sea bed is 55 feet, and 2 

per cent of this is 1.1 feet. At the same place 

the depth of water (below the plane of reference) is 34 feet, and a reduction in depth of 1.1 

feet is a reduction of 3.2 per cent. So, under 

the assumptions just made, a ~eduction of the 

bar length of 1 per cent is accompanied by a 

depth reduction (at an important locality) of. 

3.2 per cent. The computation has been made 

merely to show that the reduction of length 

tends to reduce the depth and that the tendency 

is important. It does not in fact greatly 

reduce the depth, because any reduction of 

depth increases velocity, and increase of 

velocity promotes wasting of sand, and this 

tends to reduce the volume of the bar-so the 

assumption of constant volume is untenable. 

A shortening of · the bar also has the effect 

of diminishing the crest area, on which bar 

material is worn out and wasted, and, provided 

the supply of new material is unchanged, this 

effect must be offset by a strengthening of the 

ebb velocity. The increase of velocity necessary to dispose of the excess of ·sand occasioned 

by the shrinking of the bar may be regarded 

as temporary, being no longer required ~ter 

adjustment has been effected; but the increase 

necessary to maintain a rate of wasting equal 

to the rate of supply is permanent. Thus we 

have the somewhat paradoxical result, that a· 

reduction of tidal volume, which initially 

reduces ebb velocity. across the bar, sets in 

motion a sequence· of changes of such character 

that when equilibrium has been again attained 

the ebb velocity is greater than before. 

The entire space between the crest of the 

bar and the water surface may be regarded as 

a chan.llel for the ebb discharge; it is so wide 

a channel that the· mean velocity in it is not 

appreciabiy affeoted by the channel walls, and 

there is no error in saying that the mean 

velo~ity varies inversely with the mean depth. 

It follows that the increase of velocity inferred 

through the reasoning of the last paragraph 

implies the same ratio of decrease in depth. · 

Thus it appears that the physical results following such a reduction of tidal volume as is· 

occasioned by encroaclim.en t on the tidal prism 

include (1) a retreat of the bar crest toward 

the shore, (2) a reduction of depth of water 

above the bar, and (3) an increase in the velocity of tidal currents as they cross the bar. 

The quantitative relations of the several 

effects do not appear, and the ~vailable local 

data do not suffice for their discussion,- but 

some inference is possible from the phenomena 

of other harbors. The harbors of the world 

furnish many examples in which the entrance 

'Qar lies in the line of the beach, holding that 

position because the tidal current is not strong 

enough to drive it from the line established 

by the waves; yet there may be great depth 

of water on the bar. In view of these examples 

·We may infer that if the currents of the Golden 

Gate should so weaken as to permit the bar to 

retreat to the coast line the bar would still 

carry a fair depth of water. That is, the retreat 

of the bar through its whole distance from the 

land would not be accomplished by ·a loss of 

the entire depth of water but only by a moderate fraction of it. And so the ratio in which 

the depth of water on the bar is reduced by 

encroachment on the tidal prism is believed 

to be less than the ratio in which the bar's distance from the coast line is reduced. 

It is desirable so to extend ·the analysis as 

to discover the ratio which ohange in depth of 

water on the bar bears to change in tidal discharge, but the way is not clear. If we turn 

again to the consideration of tideways which 

cross the s~ndy cordon of the coast without 

deflecting it, we see that where the discharge 

is relatively large the traversing channel is 

relatively wide and relatively deep and the 

current through it is relatively swift. Width, 
RELATIONS OF DEBRJS MOVEMENT TO THE GQLDEN GATE BAR. 99 

depth, and velocity are all direct functions of 

discharge. Width and depth are apparently 

stmilar functions, so that their rates of change 

are equal and the theoretic rate of change in 

depth is less than half the rate of change in 

discharge. Where the bar is arcuate, however, 

only width and depth are direct ftmctions of 

discharge, and velocity is an inverse function. 

If width and depth are similar functions of 

discharge, so as to have the same rate of change, 

the rate of change in depth is more than half 

the rate of change in discharge, but the "if" 

is important, for we have no information as to 

the relative rates of variation of width and 

depth. 

The preceding discussion of the effect of 

change in tidal volume assumes constancy in 

the supply of sand. Let us now assume constancy in the tidal volume and consider the 

effect of a change in the supply of sand. Evidently the immediate or initial effect of an increase ill the supply of sand is to build up the · 

bar and thus reduce the depth of water above 

it. With smaller depth the velocity is greater, 

and increase of velocity tends in two ways 

toward a readjustment in which the wasting 

of sand is equal to the supply. First, it permits larger grains of sand to· be removed in 

suspension; and second, it gives greater power 

to tidal forces in their conflict with the waves, 

with the result that the bar is pushed farther 

from the land, its length is increased, and the 

field of intensive sand wasting . i.s enlarged. 

When the new equilibrium has beep, established 

the bar crest will be farther from the land, the. 

depth of water on the bar will be less, and the 

ebb current will have a higher velocity. 

It is evident that a reduction of the supply 

of sand will result in changes of opposite oh.araoter. 

We are now ready to compare the observed 

changes in the bar with the changes which 

theoretically should follow either a reduction 

o:f tidal vohim.e or an increase or reduction of 

the supply of sand. In the following tabulation (Table 28) no mention. is made of velocities because observation.hai told us nothing of 

their changes. 

The movement of the crest line toward the 

land that was determined by comparing the 

soundings of 1873 with those of 1855 is such as 

might be occasioned either by a reduction of 

the tidal prism or by a reduction of the rate 

at which sand was supplied to the bar. The 

simultaneous loss in depth inferred from a 

comparison of the same systems of soundings 

might be occasioned by a reduction of the tidal 

prism or by an increase in the rate of sand 

supply. Reduction of the tidal pris:rp., the 

cause indicated by both the observed changes, 

is itself an observed fact, for it is known that 

during that period there were encroachments 

on the bays and also on the tidal marshes. 

As to· change in the supply of sand-a change 

concerning which the theoretic indications are 

conflicting-we lack information. 

TABLE 28.-Comparison of observed changes of the Golden 

Gate bar with changes theoretically due to specific causes. 

Character of changes theoretically 

caused byReduction Reduction ·of tidal of sand Increase of 

prism in supply. sand supply. 

the bays. 

Crest moved ...... Landward. Landward. Oceanward. 

Depth of water on crest ... : .... Reduced.~. Increased .. Reduced. 

Observed changes.a 

1855-1873 1873-1900 1855-1900 ' 

Crest moved ..... Landward L.andward Landward 

(425 feet). (465 feet). (1,125 

Depth of water Reduced Increased . feet). 

Increased on crest. (0.5foot). (1.1 feet; (0.6 foot). 

0.9 foot). 

a The figures indicating amounts of change are taken from Appendix C 

(p. 145), to which the reader is referred. The measurements of crest movement were all made within the central third of the arc of the crest, but not in precisely the same tracts, which accounts for a discrepancy 

among the figures. 'l'he figures giving estimates of change in depth are averages for the entire crest. They are from o. study by J. T. Watkins, 

except that the smaller estimate for the period 1873-1900 ~s by the writer. 

The .movement of the crest line between 

187.3 and 1900 was also toward the land, implying either a reduction of the tidal prism or a 

reduction of sand supply; but the change in 

depth for this later period was ·a gain instead 

of a loss, and gain implies either an enlargement 

of the tidal prism or a reduction of the sand 

supply. The two observed changes agree in 

indicating defect of sand supply as a cause but 

differ in their indications as to the tidal prism. 

As it is a matter of independent knowledge.that 

the tidal prism was reduced in various ways 
100 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

during that period, no part of the gain in depth 

can be assigned to enla.rgemen t of prism and 

the whole should be ascribed to a defect of 

sand supply. 

The view that the sand supply was exceptionally small dilling this period finds support 

in an observed change in the form of the bar. 

A simple landward migration, such as was 

considered in the theoretic discussion of the 

effect of reduced tidal volume, involves a landward shifting of the crest and of. the outer and 

inner faces, but the change revealed by the 

resurvey in 1900 was somewhat different. The 

outer face and the crest moved toward the 

land, but the greater part of the inner face did 

not. There was a steepening of the inner slope, 

so that while the extreme upper part moved 

somewhat toward the land the lowest part 

moved more than 1,000 feet in the opposite 

direction. The broad base of the bar was narrowed to ·an extent that was proportionally 

greater than the reduction in length or thereduction in height, and there was a large reduction in the volume of the bar. 

The fact that the bar crest was .lowered so 

as to give more depth of water, notwithstanding the reduction of tidal prism, which tended 

to cause less depth, indicates that the influence 

of change in the prism was overpowered by the 

effect of change in sand supply. The rate of 

sand supply appears -to be the preponderant 

factor in determining depth of water on the bar. 

In the preceding discussion the endeavor has 

been to draw legitimate conclusions from the 

data afforded by three surveys of the bar, and 

the accuracy of the data has been assumed. It 

remains to consider difficulties. The result 

that I :find hardest to accept is that during the 

period 1873-1900 there was a great defect in 

the supply of sand reaching the bar, a defect 

causing the bar to lose on the average 1.7 feet 

from its surface and to sustain a loss of volume 

of over 70,000,000 cubic yards. If it is admitted that the sand tribute from the rivers is 

negligible we must regard the wave-beaten 

cliffs and bluffs of the coast as the only important source of the bar's supply of sand, and 

the rate of erosion of the coast seems to depend 

on factors that afford little variation, when the 

average for 27 years is compared with the 

average for a preceding long period. Most 

of those factors are natural, and I know no 

reason to suppose they have suffered important change within the last century. Man has 

at a few points tried to retard the slumping 

of sandy cliffs toward the beach, but what he 

has accomplished is trivial and may be fully 

offset by the stimulus he has given to rain 

erosion by his plowing and road making on 

lands that di-ain directly to the coast. 

If importance is ascribed to the tribute from 

the rivers the difficulty is not less, for the period 

from 1873 to 1900 includes not only the decade 

of greatest output of sand from hydraulic 

mining but also the following decade, in which 

the delivery to the bar would presumably be 

greatest. 

The recognition of this difficulty led me to 

scrutinize the data from the surveys of 1873 · 

and 1900 with special care, as described in 

Appendix C. Their details are such that certain probable errros are readily computed, and 

the probable error of the computed mean 

change in depth for the whole bar area, an increase of 1. 7 feet, was found to be only ± 0.1 

foot. That oheck ·applies, of course, only to 

accidental errors and has no bearing on the 

question of systematic errors. My search for 

systematic errors, however, revealed none that 

helped to remove the difficulty. The chief 

discovered reason for questioning the survey 

data, aside from the bprobability of theresults to which they lead, lies in the fact that 

the methods of reducing the measurements 

made with the sounding line at different stages 

of tide to a com~on reference plane were not 

the same in 1873 and in 1900. 

SUMMARY. 

There is a continuous channel from the 

mouths of Sacramento and San Joaquin rivers 

to .the Golden Gate bar. This channel is maintained by tidal currents, and the tides are of 

such nature that the stronger ebb currents 

have higher velocity than the stronger flood 

currents. The ebb currents, moreover, are 

reinforced by the discharge from the rivers. It 

results that sand and other coarse debris delivered to Suisun Bay by the rivers and dragged 

forward and backward by the currents has a 

net movement toward the bar. While thus in 

transit it suffers attrition, and the greater part 

of it is ground so :fine as to leave the channel 

bed and pass into suspension. At Pinole Shoal, 

in San Pablo Bay, a point midway between the 

river mouths and the bar, the coarsest material 
RELATIONS OF DEBR.IS MOVEMENT TO THE GOLDEN GATE BAR. 101 

remaining in the channel bed is a fine sand, the accuracy of these indications is questioned. 

grains being about as large as those of the sand The theoretic change in depth corresponding 

which constitutes the crest of the bar. The to a migration of 1,000 feet would be less than 

course of the river sand has not been traced 6 inches, and would be a loss instead of a gain. 

beyond this point, but it is believed that very A falling off of the supply of sand is thealittle of it can survive the buffetings of the retically competent to increase depth of water 

remaining journey and find lodgment on the on the bar and at the same time cause the 

bar. crest to move toward the shore, but there is no 

The sand on the bar is stirred an~ jostled independent evidence of defective sand supply 

by storm waves, which agitate the water to during the period to which the survey data 

considerable depths, and it also is worn out. pertain. The discussion leaves open the quesThe chief source of renewal, to compensate for tion whether the apparent gain in depth was 

the waste, is the erosion of the coast. The cliffs actual, the result of an unknown change in 

are quarries worked by the waves, and the conditions determining sand supply, or was 

output in sand and gravel drifts along the apparent only, the resuit of some undiscovered 

beaches to the tidal currents. of the Golden defect in methods of survey. 

Gate. In samples of sand from the bar it was There is no reason to believe that mining 

found easy to recognize. material that could debris by deposition on the bar has affected 

have come only from the coast or from the or might affect the depth of water on the bar 

Golden Gate, but attempts to identify material to any appreciable extent. There is good 

from the rivers were unsuccessfu1. reason .to believe that mining debris and the 

The depth of water on the bar depends partly soil waste promoted by agriculture and other 

on the rate at which sand is supplied to it and industries have reduced and will reduce the 

partly on the strength of tidal currents. The depth of water by reducing the strength of 

strength of currents depends in turn on the tidal currents, their effects in this direction 

volume of the tidal prism. The effective tidal being combined with the similar effects of r~­

prism is the space between the position of the claiming tidal marshes on the borders of the 

water surface in the bays when the outward bays. · 

flow begins at the Golden Gate and the posi- Encroachments on the tidal prism of Suisun 

tion of the water surface when the outward Bay have less influence on the currents in the 

flow ends. The volume of the prism has been Golden Gate than similar encroachments in 

reduced and is being reduced in three ways- the lower bays. The reclamation of marsh 

by the filling of shoals and construction of lands adjoining Suisun Bay and Napa River 

piers, by the reclamation of tide marshes,· aJ?.d has about half as much influence on the Golden 

by the deposition on shoals in the bays of Gate currents as the reclamation of marsh 

debris brought by rivers and creeks. It is esti- ·lands adjoining the southern part of San 

mated that the encroachment thus caused by Francisco Bay. The currents are little affected 

mining debris and general soil waste has affected by the reclamation of marsh lands of the river 

the tidal prism to the extent of 2 or 3 per cent, deltas; reclamation near the river mouths 

and the encroachment from marsh reclamation tends to weaken the currents, and ~eclamation 

about 1.5 per cent. in the remoter parts of the deltas to strengthen 

Theoretically the reduction of the tidal prism them. 

should occasion two changes in the bar-a PINOLE SHOAL AND MARE ISLAND STRAIT. 

migration of the crest toward the land and an 

upward growth, reducing the depth of water The establishment and maintenance of a 

on the crest. A comparison of charts made United States navy yard on Mare Island has 

from surveys in 1855, ·1873, and 1900 shows given special importance to the shoaling of the 

that in each interval between surveys the crest San Pablo channel and to the formation of a 

migrated toward the land, the entire change shoal at the mouth of Napa River, for the 

of position being nearly or quite 1,000 feet. maximum draft of vessels that can pass from 

The same charts indicate a loss in depth of 6 the ocean to the navy yard is determined by 

inches between 1855 and 1873, and a gain of 1 .the depth of water at these points. The comfoot between 1873 and 1900, giving a net gain merce of the region about Carquinez Strait is 

of 6 inches between 1855 ·and 1900, but the. also affected, though in less degree. Dredging 
102 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

has be.en resorted to at both points, and the 

maintenance of adequate depth has become 

both costly and precarious. 1 

It is to be observed, however, that the naval 

difficulty would have arisen even if there had 

been no shoaling, for war vessels of rnodern 

maximum draft could not have reached Mare 

Island at the time the locality was selected for 

a navy yard. 

The channel through San Pablo ·Bay is bordered on both sides by broad shoals, and its 

banksand bed alike are composed of deposited 

debris. It is shaped by the tidal currents 

which traverse it, and its dimensions are determined partly by the volume of those currents, 

supplemented from time to time by river 

floods, and partly by the rate of influx of 

debris. Because of the reduced volume of 

tidal currents and because of the increased influx of debris, the bordering shoals have grown 

at the expense of the channel, and at the same 

time the channel· depth has been reduced except for a central groove created by dredging. 

Between the years 1856 and 1897 the channel 

width at the 3-fathom contour was reduced 

from 10,870 to 8,300 feet. In an official report 

on channel improvement at Pinole Shoal the 

loss in depth between 1856 and 1899 has beenestimated at 2 feet. · 

The reduction of tidal discharge was occasioned in part by deposits on the shoals of 

Suisun Bay, in part by the reclamation of 

marsh lands which had received tidewater 

from the Napa estuary, and in part by the reclamation of tide marshes of the SacramentoSan Joaquin delta. It is especially to be 

noted that the storage of .tidewater on the 

delta, while of no importance with reference to 

currents in the Golden Gate, contributed much 

to the currents on Pinole Shoal. It has been 

estimated (see Table 22, p. 83) that when all' 

the delta marshes shall have been reclaimed 

the great tropic ebb current across Pinole Shoal 

will have lost one-sL.xth of its volume and that 

1 The first dredging on Pinole Shoal was in 1904-1906 and produced a 

trench about 5 miles long with a bottom width of 300 feet and side slopes 

of 1 in 3. Before the end of 1910 it had been filled and obliterated. In 

1912-13 a new trench was dug, with a bottom width of 500 feet and side 

slopes of 1 in 5. Up to June 23, 1913, the appropriations for the work 

amounted to $1,153,168.41, and it had been estimated that the maintenance of that trench would cost $100,000 annually. In 1898-1900 M:are 

Island Strait was deepened by dredging. A plan for further improvements, recommended and approved in 1908, called for an initial expenditure of $1,007,000, to be followed by the annual expenditure of $70,000 

for maintenance. In 1913 plans involving contract dredging were abandoned, and the first steps were taken for the construction of a Governmentowned dredge to be used on Pinole Shoal and in Mare Island Strait. 

an additional tenth of the volume may be cut 

off by the complete reclamation of the Suisun 

marshes. 

The abridgment of tidal area occasioned by 

the silting up of Suisun Bay has been estimated 

to reduce the volume of tidal currents in the 

Golden Gate by more than 2 per cent. The 

corresponding estimate for Pinole Shoal is a 

reduction of tidal volume 'by more than 9 per 

cent. 

By the engineering works for the control of 

Sacramento River floods the flood discharge of 

the river will be increased, and the increase will 

reinforce the ebb .current on Pinole Shoal at a 

critical time, because then the water is most 

highly charged with sediment. This advantage 

will be partly or perhaps wholly offset by 

the fact that the bays will then receive all the· 

debris that is now caught by the lateral basins 

of Sacramento Valley. 

The lower part of Napa River is a tidal estuary and has an average width of 1 mile. Near 

its mouth, where it communicates ·with Carquinez Strait and San Pablo Bay, it is constricted into the narrows known as Mare Island· 

Strait. On the north and west the- estuary 

adjoins extensive marshes, and it receives the 

tidal sloughs of the marshes~ The strait is the 

channel through which tidal waters flow to and 

from the estuary and marshes, and the original 

depth of water in the strait was determined by 

the tidal currents, conditioned by the small 

amount of debris which came with the river 

floods. In the early fifties, when the site for 

the navy yard was selected, the least depth of 

water in the strait was greater by a fathom 

than the least depth on Pinole Shoal. There 

were then no encroachments on the tidal storage of the marshes, and the influence of the 

mining debris had not been felt. In 1898, 

after the tide had been excluded from a portion 

of the marsh land and after the great influx of 

debris from mines and fields, the least depth 

was found to have· diminished from 27 feet to 

15 feet. 2 · The shoaling has been ascribed to 

the change in debris conditions, and I am not 

aware th~t the influence of reclamation has 

been mentioned in this connection, but there · 

need be no question that the impairment of 

the channel has been caused in part by the 

2 'rhe history of change is given in the report of a board of Army and 

.Navy officers "appointed to investigate the hydraulics of Mare Island 

Straits and approaches, with a view to improvement" (60th Cong., 2d 

sess., H. Doc. 1103, 1908). 
RELATIONS OF DEBRJS MOVEMENT TO THE GOLDEN GATE BAR. 103 

weakening of the tidal currents. A close estimate of the extent to which the currents have 

been weakened is not practicable, because the 

marsh tract lying west of the estuary has not a 

definite boundary. It merges with a tract 

draining to Sonoma Creek, and the joint tract 

is traversed by a system of connecting sloughs. 

In preparing the data for Tables 17 and 22 I 

drew an arbitrary line of separation on the 

map, and the marsh· lands thus assigned to 

Napa River had an area of 26 square miles; 

the area of the estuary is 5 square miles. On 

the basis of this classification the currents 

through the strait derived 60 per cent of their 

volume from the tidal prism of the estuary 

and 40 per cent from the tidal storage of the 

marshes. Prior to the first mapping of the 

region (Napa quadrangle) by the Geological 

Survey in 1899 about one-fourth of the marsh 

area had been reclaimed, so that 1.0 per cent 

may be used as an estimate of the loss in tidal 

volume in 1898. The amount of shoaling that 

would adjust the channel to this change and 

preserve the same velocity of tidal current is 

about 3 feet; and this is to be compared with 

ap. actual shoaling of 12 feet. These figures 

would doubtless be modified somewhat if the 

data as to the marsh lands were more exact, 

but their general indication may be acceptedthat reclamation is responsible for an important 

fraction of the trouble from deposition in the 

strait. · 

The work of reclamation continues and bids 

.fair to exclude the tides from all the marsh 

area except some of the larger sloughs. It 

will then have reduced the tidal discharge to 

about two-thirds of its original amount. Later 

mapping by the Geological Survey (Mare Island 

quadrangle) indicates that in 1914 more than 

half the marshes tributary to Napa River had 

been reclaimed, and that levees abo:ut still 

other tracts were then under construction. 
CHAPTER X.-THE OUTLOOK FOR HYDRAULIC MINING. 

The interests that suffered most acutely and 

consciously by reason of the great wave of mining debris from the Sierra were those of lowland 

farm lands and lowland towns. Some farms 

w~re buried, and for others the cost of protection fron1 inundation was increased. Towns 

had to levee against sands and rising floods and· 

were deprived of the advantages of river transportation. In respect to these interests the 

period of tension is now past. The piedmont 

rivers have intrenched themselves in the piedmont deposits, and their sands have ceased to 

spread. The valley rivers are lowering their 

beds, and the full resumption of river traffic is 

in sight. The debris in the river beds has lost 

prominence as a factor in the aggravation of 

floods, being now clearly subordinate to the 

reclamation factor. 

The remoter effects of the debris invasion, 

though not neglected by the Government 

engineers in charge of rivers and harbors, received little attention from the general public, 

despite the fact that the integrity of the harbor 

is of higher importance to the community as a 

whole than the navigability of the rivers. 

The building of the piedmont deposits gave 

to· the channels of the piedmont rivers such 

slopes that they are now able to carry forward 

a much larger annual load of debris than in 

pre-mining years. The system of levees by 

which the valley floods are being controlled is 

giving to the valley rivers also an ability to 

transport a greater annual load. So far. as 

riparian interests are concerned it would soon 

be possible to admit to the rivers a considerable 

annual load of mining tailings without a recurrence of the old-time tension. Such a modification of the existing system of .regulation is. 

inadmissible chiefly or wholly because the consequence would be prejudicial to navigationbecause it would tend to diminish the depth of 

water in the rivers, on Pino1e Shoal, and on the 

Golden Gate bar. 

Back of this proposition lie certain postulates 

as to relative values. I tis true that the present 

restrictions on mining were determined in chief 

104 

part by considerations of justice between two 

local interests-the miners should not continue 

their work in a manner injurious to property in 

the valley-but San Francisco Harbor belongs 

to the whole community, and it is proper for 

the community to weigh its impairment, in such 

measure as it might be impaired, against the 

advantage to the community of having the gold 

extracted from the Sierra gravels. So too the 

community-or the custodians of its interestsmay weigh the embarrassment· of navigation in 

bays and rivers against the advantages from 

gold extraction. The regulations that restrain 

hydraulic mining should not be made less stringent unless the advantage from the mining is 

of greater moment to the community than the 

disadvantage to navigation that a change of 

policy might entail. 

In this connection it is to be observed that 

the public and its representatives may properly 

consider to what extent'' the interests of agriculture and commerce are brought into antagonism by existing conditions in the bays. Now 

that the flow of mining debris is waning the 

flow of soil waste, whose effects are of the same 

character, is acquiring relative importance. 

Soil waste is mainly the t&ilings of agriculture, 

and through it agriculture is obstructive to 

navigatio'n and commerce. Coordinate with 

the weakening of the Golden Gate currents by 

deposits of mining debris and soil waste is the 

weakening caused by the reclamation of tidal 

marshes, and nearly all that reclamation is for 

the purposes of agriculture. That agriculture 

in its entirety is the industry of first importance 

is recognized by all, but it does not follow that 

commerce should yield to it at every point of 

interference. Each particular case of conflicting interest involves an economic problem in 

relative values and should be adjudged on 

that basis. 

As to soil waste there is no essential conflict 

of interest, for the conservation of soil is more 

important to agriculture than to commerce. 

The injury to commerce is occasioned only by 

the improvident and profligate methods of 
THE OUTLOOK FOR HYDRAULIC MINING. 105 

frontier farming. In time the methods will 

be reformed without regulative compulsion, 

and· it is possible that this result may be 

achieved somewhat quickly through education, but if i~ must await for its motive a 

strong pressure of population on agricultural 

area much harn1 to navigation may first be 

caused. 

In respect to reclamation the interests of 

agriculture and commerce are directly· antagonistic. Every acre of reclaimed tide marsh 

(except in the upstream parts of the river 

deltas) implies a fractional reduction of the 

tidal current in the Gold.en Gate. For any individual acre the fraction is minute, but the 

acres of tide marsh are many, and if all shall 

be reclaimed t.he effect at the Golden Gate. 

will not be minute. The question whether the 

community should make a large addition to its 

permanent agricultural wealth at the cost of a 

small permanent injury to its great harbor is 

a question of relative values. 

Returning to the consideration of hydraulic 

mining, I shall assume that, in the future as 

now, the working 'of the auriferous gravels will. 

be permitted only on condition that the tailings, 

coarse and fine, are kept from the rivers. 

The history of mining under permit has 

served to bring out certain economic limitations. When the system of regulation was 

first established its rules were framed especially 

for the immediate arrest of the coarser debris. 

Much of the finer material was allowed to escape, and the types of impo'unding dams prescribed were not such as to make the debris 

storage permanent. Rules ·formulated later 

were more stringent, and the expense to the 

miner was increased, especially by the requirement that his dams have the quality of 

permanence. Partly hecause of the increasing 

stringency of regulation, and partly because 

of the exhaustion of the richer gravels and of 

the more available storage sites, the industry 

has slackened, and its magnitude is now relatively small. With minor exceptio~.s, the 

gravels that remain in the Sierra can not be 

worked profitably so long as the cost of storage 

is added to the cost of washing. 

With the lapse of time, also, the money value 

of water power has risen. Hydraulic mining 

must now compete with those valley industries which obtain ·power from the Sierra 

through electric transmission, and the restrictions thus imposed on mining increase with the 

development of the power-using industries. 

In the near future agriculture, which has 

postponed the full utilization of. Sierra waters 

for irrigation, will be imperative in demanding 

a large share in the control of the streams, and 

the arrangements to meet. the joint needs of 

irrigation and electric power are likely to so 

increase the storage of water in reservoirs that 

mining will have comparatively little opportunity for that use of surplus or otherwise unappropriated water which it now finds a 

resource. 

As a result of the enlarged and growing cost 

of hydraulic mining the quantity of auriferous 

gravel that can be worked at a profit is less 

than it was 25 years ago. If the estimates 

made at that time were to be shorn of all exaggeration they would still need much paring to 

bring them into accord with present conditions. 

In the memorial of the California Miners' 

Association (p. 12) asking for an investigation 

by the Geological Survey it was suggested that 

waste lands might be found in the foothills on 

which the mining debris could be deposited. 

The lands that are waste in the sense of having 

little or no value for agriculture are lands of 

steep slope, on which the debris could not be 

deposited without expensive dams. Deposition in the foothills could not in any case be 

accomplished without local control of the 

rivers, and such control would be more expensive than the control of streams near the 

mines. 

Various schemes have been broached for the 

storage of mining debris in one of the lateral 

basins of the Sacramento. The cost would 

include engineering works for the control of 

large streams .and also the purchase of the 

lands to be covered by the deposit, and such 

. cost would be greater than the benefited mining industry could afford. Nevertheless, such 

projects are not necessarily visionary, because 

the mining interest is not necessarily the only 

one to receive benefit. A project of that kind 

might include the complete protection of a piedmont deposit of mining debris from further 

erosion and thus deserve consideration by the 

State· as a measure for the conservation of San 

Francisco Harbor. 

The reasons that have been given by engineers for the· rejection of such schemes have 

included interference with vested rights, pro-
106 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

hibitive cost, and inadequate fall or slope. be sent to the bays and that the chief parts of 

While I do not question that the second reason , the unworked auriferous gravels are not rich 

is adequate, it seems to me desirable to point enough to meet the expense of permanent 

out that the third is fallacious. It is indeed storage of tailings, whether in the mountains, 

true that a stream which carries a load of in the foothills, or in the vall~y, the outlook 

debris can not carry its load ori a route giving for any important enlargement of the hydraulic 

less slope if other conditions remain the same, mining operations is certainly not assuring. 

but it is also true that on most streams the There remains, however, a possibility that 

ability to carry load may be greatly increased something may be accomplished through coop-

. by reducing the width of channel. An unre- eration · with other industries. Cooperation 

strained stream that has a load to carry shapes between the great users of the Sierra water, the 

for itself a wide, shallow channel, whereas the irrigator and the distributor of power, has 

channel form most efficient for the transpor- probably already begun; if not, then it impends, 

tation of debris is narrow and deep. It results for it is the logical relation; and there may be 

that a stream with a :fixed load which has ad.:. places where to the interests of these two the 

justed its slope to a wide channel can be made interests of the miner can be joined, so that a 

to do its work on a gentler slope by narrowing single plant for water control may serve three 

its channel. purposes. 

As already mentioned (p. 63); this principle In a tentative way I have dev~loped such a 

is illustrated by-results from the training walls project for the control of Yuba River at the 

at Daguerre Point; and it is further illustrated edge of the Great Valley, and the scheme will 

at the narrows of Yuba River near Smartsville. be presented in brief· outline, notwithstanding 

In the narrows, where rock walls determine a the fact that I have been informed by a comwidth of 300 to 400 feet, the Yuba established petent engineer that the cost of the projected 

a slope of 5 feet to the mile as appropriate to works would be prohibitive. The project will 

the transportation of its load of coarse gravel serve to illustrate my idea as to the general 

at a time when the movement of mining debris character of possible cooperative undertakwas near its maximum. Outside the narrows, ings, and it may contain suggestions toward a 

where the width of the flood channel was 1,000 better-considered scheme. 

to 1,500 feet, the slope adjusted to the same South of the Yuba near Hammonton is an 

load was about 18 feet to the mile. Had the outlying foothill of which the north base is 

rock walls at the narrows been smooth instead called Hallett Point. It is connected with the 

of uneven, a slope of less tha:p. 5 feet to the main line of foothills by a ridge, which is 

mile would have been established there. If notched at several points by cols. The project 

the river were to be constrained by smooth includes a dam running straight northward 

training walls 400 feet apart all the way from from this hill and of such height as to divert 

the na~ows to its mouth, 20 miles away, and the river across one of these cols. The diverted 

if the height of the bed at the river mouth river would follow the line of Reed Creek to 

were to be so determined by a sill that the Feather River, being guided by training walls. 

slope from narrows to sill would serve for the The reservoir ereated by the dam would have 

transportation of a maximum load of debris, an initial capacity of 560,000,000 cubic yards, 

the height of the sill would be more than 100 or 350,000 acre-feet. It would catch and 

feet above the highest flood level of Feather store all debris delivered by the river, except 

River. It would be feasible, therefore, as a· the very finest. If the old mining debris and 

project in hydraulic engineering and without the soi.l waste for 50 years are estimated at 

reference to. cost, to carry Yuba River by an 100,000,000 cubic yards the reservoir cou).d 

aqueduct across Feather River, taking with it still ·receive 250,000,000 cubic yards of new 

the largest load of debris ever imposed on it mining debris before its serviceability for irriby mining and. delivering the load in Sutter gation and power development would begin 

Basin. to be impaired. In computing power developIf it is true, as I believe, that the community ment I assumed that the head would vary 

can not afford to permit more mining debris to from 175 to 95 feet, the daily requirement in 
THE OUTLOOK FOR HYDRAULIC MINING. 107 

discharge being inversely as the head, and I 

computed only the theoretic power, without 

allowance for the coefficient of efficiency. I 

assumed that the development of power would 

be uniform through the year, so that during 

the height of the irrigation season a certain 

portion of the discharged water would not be 

utilized for power but only for irrigation. In 

computing the acreage for irrigation, I allowed 

a duty of one-third acre per acre-foot and estimated the quotas of water for different months 

on the basis of the experience at Orland .. The 

run-off of the Yuba River basin was taken 

month by month from gaging records at the 

narrows, and the monthly requirements for 

power and irrigation were treated in combination with the monthly run-off, so as to take 

continuous account of the water level in the 

reservoir. An allowance of 10 per cent was 

made . for evaporation and seepage. Independent computations were made (1) for the 

average annual run-off and (2) for the smallest 

recorded run-off, that of the year 1910. The 

resulting figures are as follows: 

TABLE 29.-Irrigation and powe:r from YUba River project. 

Area furnished with water for irriWith av- With runer~r/un- off of 1910. 

gation ................... acres.. 159,000 

Continuous (theoretic) power de133,000 

veloped ............ horsepower. . 27, 600 20,400 

The intake of the irrigation canals, being 

below the outfall of the projected power house, 

was placed at the 100-foot contour above sea 

level, and the lands to be served all lie east of 

Feather and Sacramento rivers and north of 

American River. The tracts under the lines 

of canal, after deducting lands already irrigated in 1912 and after deducting 10 per cent 

for roads, etc., contam 191,000 acres. 

If such a reservoir were to be used only for 

the storage of debris, its capacity would be 

about 750,000,000 cubic yards, and the provision for new hydraulic tailings would be 

650,000,000 yards, instead of the 250,000,000 

admitted in 1 the cooperative scheme. If it 

were to be used for power development alone 

the output estimated, for a year like 1910, is 

26,700 horsepower, instead of 20,400. If it 

were to be used for irrigation alone, high-level 

as well as low-level canals could be employed, 

increasing the available area east of Feather 

and Sacramento rivers to about 350,000 acres; 

and the water supply in a year like 1910 would 

suffice for about 300,000 acres. 

In addition to its service in power development and its service to agriculture and mining, 

the project would benefit commerce by increasing or conserving the depth of water at points 

of critical importance to navigation. Not only 

would it arrest a large body of soil waste and 

old mining debris at its point of issue from the 

mountains, but it would fix: beyond possibility 

of future erosion all·that remains of the Yuba 

piedmont deposit. The Yuba, which now 

brings more debris to clog the navigable channels below Marysville than all other streams 

combined, would be loaded only with fine 

mud in suspension, and its water would help 

to scour channels deeper; while the regulation 

of its flow would increase the low-water discharge and the low-water depth on river bars. 

The trouble at Pinole Shoal would be slightly 

reduced, and the contraction of the bays which 

is slackening the tidal current at the Golden 

Gate would be retarded. The. project would 

thus serve the interests of the community as 

a whole, and because of this service the $tate 

might assume, without injustice to its taxpayers, a share of the cost. 
APPENDIX A.-OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 

PURPOSE AND PLAN OF THE WORK. ering a period of 24 hours, made on such dates 

In discussing the effects of encroachments that one should compass an epoch of lunar high 

on the tidal prism of the San Francisco Bay declination and the other an epoch of zero decsystem it was found important to estimate the lination. The locality selected was the middle 

contributions made ~y the different parts of of the strait at its narrowest constriction, bethe prism to the currents flowing through the tween Fort· Point and Lime Point. Because 

Golden Gate. The computations required, in the clirrents there are strong and the depth is 

addition to data furnished by the Coast Survey great, the mooring of a vessel is not easy, but 

Tide Tables, a knowledge of the time intervals this. difficulty was o~ercome throug~ the coopfrom high water to the following slack water eratwn of the LI~hthouse Serv~ce. Capt. 

and from low water to the following slack ·Harry W. Rhodes, Inspector ~f ligh~houses, 

water~ It .was because existing information· ancho:ed a steel buoy at the desrred pomt, and 

as to these intervals was not satisfactory that to . this buoy was moore~ the patrol boat 

the observations here to be described were un- Su?-Sun, ·placed at our service by the courtesy 

dertaken. of Lieut. Col. Thomas H. Rees, United States 

The time of slack water in any part of a tidal Army, engineer officer ~charge of rivers a~d 

channel is the time at which the direction of .harbors. The undertaking was largely mthe current changes· from outward to inward deb ted for its measure of success to the assistor from inward to outward. It is not the ance rendered by these gentlemen and by Capt. 

same for all parts of a cross section of channel, L. ~· W estd~~~'. assistant ~ charge of the 

and there is often a long period during which Pacific coas~ divisiOn of the United States Coast 

the currents in different parts of the section and Geodetic Survey. 

have opposite directions. For the purpose of THE OBSERVATIONS. 

the present study the point of time desired is 

that in which the inward elements of current 

at the Golden Gate are balanced by the outward 

elements, so that the net movement of water 

in either direction is zero. Direct observation 

of this time is impracticable, because of the 

difficulty of making simultaneous observations 

at many points on and below the surface of the 

water. The indirect method of determination 

that was employed was suggested by Dr. R. A. 

Harris, of the United States Coast and Geodetic Survey, to whose expert advice I am indebted in many ways. It consists in observing 

directly the velocity of the main current during 

its ebb and flood phases, so as to determine the 

general sequence of changes and especially the 

times of greatest strength, and then inferring 

the times of net slack water by interpolation.· 

Incidentally this procedure has given information as to the total volume of water passing the 

strait during a tidal period. 

The general plan for the field work included 

two series of curren~ measurements, each cov108 

As shown by the map (fig. 21), the strait is 

narrowest opposite Fort Point. Between Fort 

Point and Lime Point the ebb current moves 

in a single body, but just beyond the constriction there are shore eddies; and the same statemfmt is true of the flood current. To avoid 

complication by eddies it was desirable, with 

reference to the computation of discharge, to 

make the observations on the line between the 

two points, but because of a telegraphic cable 

on that line anchorage there is forbidden, and 

the mooring was accordingly placed somewhat 

farther west. A depth of 54 fathoms was 

found at the position of the anchor, and this 

necessitated a ·somewhat greater length of connecting cable, with the result that the positions given to the mooring buoy by the ebb 

and flood currents were several hundred yards 

apart. As the boat trailed downstream from 

the mooring, and as the observations were 

made near the stern of the boat, the observation stations were farther separated than the 
OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 109 

positions of the buoy. · As determined . from 

time to time by sextant observations, and as 

shown on the map, the stations were about onefourth mile apart. The more easterly station 

was not far from the direct line between Fort 

Point and Lime Point. 

The chief observer was Roger C. Rice, assistant engineer, United States Geological Survey. 

l~IGURE 21.-'l'ho narrows of tho Gold on Gate, showing the configuration 

of tho bottom (contour interval, 10 fathoms).and the position of the 

Uno of smallest section. Groups of circles indicate positions of the observation boat during current observations in September, 1914. Details of tho contours are from manuscript charts in the archives of the 

United States Coast and Geodetic Survey. Scale, 3 inches= 1 mile. 

lie was assisted in the first series of observations by Arthur Taylor, instructor in engineering, Stanford University, in the second by 

Charles Leidl, junior engineer, United States 

Geologicol Survey. 

The periods of observation were from 11.10 

a. m. September 12 to 10.50 a. m. September 

~ "•r. 

13, 1914; and from 10.17 a. m. to 11.31 p. m. 

September 19, 1914. The occupation of the 

station for the full period of 24 hours on the 

second occasion was prevented by the occurrence of fog, which made it unsafe for a boat 

to lie at anchor in the fairway of the harbor 

entrance. 

During the first of the two periods of observation the tides were tropic and neap; during 

the second, equatorial and spring. The astronomic dates, given below, are stated in standard tim~ of the 120th meridian, the hours being 

numbered in a single series from midnight to 

midnight. 

TABLE 30.-Lunar epochs associated with periods of observation of tidal currents at the Golden Gate. 

Date. Time. 

H. m. Moon at last quarter. . . . . . . . . . . . . . . . . Sept. 12.. 9 48 

Moon farthest north. . . . . . . . . . . . . . . . . . .. do. . . . . 23 11 

Moon on equator. . . . . . . . . . . . . . . . . . . . Sept. 19.. 13 10 

New moon .............................. do ..... 13 33 

Current observations were made with a Price 

meter, lowered to a depth of 35 feet. As a 

check on its work a few simultaneous observations were made with an Eckman meter, and 

a long.er series with a meter of the Haskell 

type, but only the Price meter records were 

used in the final discussion, and only those are 

here reported. 

Table 31 contains the observations on velocity or, more strictly, the velocities measured by the observations. In the use of the 

instrument the revolutions of the meter 

vanes are heard, by telephone, as clicks; the 

clicks are counted during a period measured 

by a stop watch; and the velocity is then 

obtained from a rating table: The instruments 

used had previously been rated in the usual 

manner. 
110 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

TABLE 31.-0bservations of tidal currents in Golden 'Gate, Sept. 12-13 and Sept. 19, 1914. 

[The observatlom of the first series (Sept. 12-13) were made with Price meter No. 891-l with single-point head (rated Nov. 6.t 1913); those of the 

second series (Sept. 19) with Price meter No. 903, with penta head (rated July 20, 1914). Depth of observation, ;j5 feet.] 

Date. 

Sept. 12 

First series. 

Time. Velocity. Direction. Observer. Remarks. 

H. m. '11 10 

11 13 

11 17 

11 19 

11 20 

11 21 

11 23 

11 25 

11 40 

11 42 

11 45 

11 55 

11 58 

12 10 

12 12 

12 14 

12 15 

12 18 

12 26 

12 -28 

12 30 

12 33 

12 35 

12 40 

12 41 

12 43 

13 04 

13 06 

13 07 

13 09 

13 26 

13 27 

13 29 

13 30 

13 32 

13 33 

13 55 

13 57 

13 58 

13 59 

14 15 

14 16 

14 17 

14 18 

14 37 

14 40 

14 41 

14 45 

14 57 

15 00 

15 04 

15 06 

15 20 

15 21 

15 23 

15 24 

15 40 

15 42 

16 00 

16 02 

16 04 

16 06 

16 08 

16 25 

16 27 

16 28 

16 48 

Ft. per sec. 1. 39 Ebb ..... R. C. Rice .... . 1. 41 ... do .......... do ........ . 1. 23 ... do ..... A. Taylor ..... . 1. 83 ... do .......... do ......... Erratic. 

1. 91 ... do .......... do ........ . 1. 79 ... do .......... do ........ . 1. 63 ... do .......... do ......... Good. 

1. 69 ... do .......... do......... Do. 

1. 45 ... do ..... R. C. Rice .... . 1. 54 ... do .......... do ......... Boat rolled. 

1. 43 ... do .......... do......... Do. 

1. 30 ... do .......... do ........ . 

1. 35 ? ..... do ...... ·... The time of change from ebb to flood was indefinite. At 

1. 04 ? ••••• do......... 12.15 the boat was swung halfway, effects of wind and 

1. 20 ~? ..••• do .••••••••• } 

1. 14 ~? ••••. do......... tide balancing. 

1. 22 ? ••••• do ........ . ;L 14 ?) A. Taylor ...•... . 80 Flood ......... do ........ . . 98 ..• do .......... do ........ . . 99 ... do .......... do ........ . . 99 ... do .......... do ........ . . 95 ••• do .......... do ........ . 1. 03 ... do .......... do ........ . 1. 27 ... do .......... do......... Boat rolled. . 95 ... do .......... do ........ . 1. 84 ... do ..... R. C. Rice .... . 1. 65 ... do .......... do ........ . 1. 81 ... do .......... do ........ . 1. 75 ~ .. do ........•. do ........ . 1. 96 ... do ..... A. Taylor ..... . 1. 78 ... do .......... do ........ . 1. 93 ... do .......... do ........ . 1. 87 ... do .......... do ........ . 2. 06 ... do .......... do ........ . 1. 87 ... do .......••. do ......... . 2. 22 ... do .......... do ........ . 2. 32 ... do .......•.. do ........ . 2. 37 ... do .....••.... do ........ . 2. 42 ... do ........... do ........ . 2. 52 ... do .......... do ........ . 2. 37 ... do .......••. do ........ . 2. 47· ... do .......... do ........ . 2. 52 ... do ....•..... do ........ . 2. 64 ... do .......... do ........ . 2. 58 ... do .......... do .. : ..... . 2. 58 .... do .......... do ........ . 2. 64 ... do .......... do ........ . 2. 71 ... do .......... do ........ . 2. 78 ... do .......... do ... , .... . 2. 85 ... do .......... do ........ . 2. 85 ... do .......... do ........ . 2. 97 ... do .......... do ........ . 2. 97 ... do .......... do .......... . 2. 67 ... do .......... do ........ . 3. 04 ... do .......... do ........ . 2. 91 ... do .......... do ........ . 2. 97 ... do .......... do ........ . 2. 23 ... do ..... R.·C. Rice .... . 2. 39 ... do .......... d~ ........ . 2. 39 .... do .......... do ........ . 2. 27 ... do .......... do ........ . 2. 39 ... do .......... do ........ . 1. 93 ... do ..... A. Taylor ..... . 1. 99 ... do .......... do ........ . 1. 87 ... do .......... do ........ , 1. 57 ... do .......... do ........ . 

Rolled slightly. 

Do. 

Do. 

·Do. 

Du. 

Do. 

Do. 
Date. 

Sept. 12 

Sept. 13 

OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 

TABLE 31.-0bservations of tidal currents in Golden Gate, Sept. 12-13 and Sept. 19, 1914-Continued. 

· First series-Continued. 

Time. Velocity. Direction. Observer. 

H. m. 16 50 

16 53 

16 55 

16 56 

17 00 

17 23 

17· 25 

17 27 

17 28 

17 30 

17 31 

17 33 

17 37 

17 39 

17 40 

17 42 

17 44 

17 45 

17 47 

17 52 

17 54 

17 55 

17 56 

17 58 

20 30 

20 34 

20 36 

20 46 

20 48 

20 50 

20 52 

20 59 

21 09 

21 25 

21 27 

21 30 

21 46 

21 49 

22 00 

22 03 

22 05 

22 16 

22 18 

22 22 

22 34 

22 35 

22 37 

22 49 

23 20 

23 22 

23 23 

23 47 

23 48 

23 52 

23 53 

23 57 

23 58 

0 00 

0 03 

0 15 

0 17 

0 20 

0 22 

0 25 

0 26 

0 33 

0 50 

0 52 

0 54 

Ft. per sec. 1. 72 Flood . . . A. Taylor ..... . 1. G6 ... do .......... do ........ . 1. 66 ... do .......... do ........ . 1. 69 ... do.· ......... do ........ . 1. 72 ... do .......... do ........ . . 75 ... do ..... R. 0. Rice .... . 1. 01 ... do .......... do ........ . 1. 35 ... do .......... do ........ . 1. 08 ... do .......... do ..... · ... . . 74 Ebb .......... do ......... . 1. 07 ... do .......... do ........ . 1. 01 ... do .......... do ........ . 1. 18 ... do ..... A. Taylor ...... . 1. 35 ... do .......... do.~ ...... . 1. 20 ... do ....... _. .. do ........ . 1. 38 ... do .......... do ........ . 1. 16 ... do .......... do ........ . 1. 32 ... do ....... .' .. do ........ . 1. 32 ... do .......... do.- ....... . 1. 20 ... do ..... , .... do ...... : .. 1. 32 ... do .......... do ........ . 1. 20 ... do .......... do ........ ~ 

1. 26 ... do .......... do ........ . 1. 28 ... do .......... do ........ . 5. 69 ... do..... R. 0. Rice .... . 5. 25 ... do .......... do ........ . 5. 01 ... do .... · ...... do ........ . 5. 17 ... do .......... do ........ . 5. 33 ... do .......... do ........ . 5. 69 ... do .......... do ........ . 5. 47 ... do .......... do ........ . 5. 59 ... do .......... do ........ . 5. 50 ... do .......... do ........ . 5. 59 ... do .......... do ........ . 5. 50 ... do .......... do ........ . 5. 59 ... do .. ~ ....... do ........ . 5. 50 ... do .......... do ........ . 5. 41 ... do .......... do ........ . 5. 59 ... do· .......... do ........ . 5. 17 ... do .......... do ....... .. 5. 69 ... do.~ ........ do ........ . 5. 25 ... do .......... do ......... . 5. 41 ... do .......... do ........ . 5. 25 ... do .......... do ........ . 5. 99 ... do .......... do ........ . 5. 69 ... do .......... do ........ . 5. 59 ... do .......... do ....... .. 5. 59 ... do .......... do ........ . 4. 54 .... do .......... do ........ . 4. 36 ... do .......... do ........ . 4. 54 ... do .......... do ........ . 3. 31 ... do .......... do ........ . 3. 78 ... do .......... do ........ . 3. 19 ... do .......... do ........ . 3. 43 ... do .......... do ....... .. 3. 03 ... do .......... do ........ . 3. 31 ... do .......... do ........ . 3. 13 ... do .......... do ........ . 3. 13 ... do .......... do ....... .. 2. 52 ... do .......... do ........ . 2. 43 ... do .......... do ........ . 3. 49 ... do .......... do ....... .. 2. 73 ... do .......... do ........ . 2. 91 ... do .......... do ........ . 2. 97 ... do .......... do ........ . 2. 98 ... do .......... do ........ . 2. 47 ... do .......... do ........ . 2. 47 ... do .......... do ........ . 2. 35 ... do .......... do ........ . 

Sea rolled higher. 

Do. 

Do. · 

Remarks. 

Boat rolled sideways pretty strongly . Do. 

Do. 

Good. 

Boat rolled. . 

O.K. 

71139°-17--8 

·111 
112 

Date. 

Sept. 13 

HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

TABLE 31.-0bservations of tidal currents in Golden Gate, Sept. 12.:..13 and Sept. 19, 1914-Continued. 

First series-Continued. 

Time. Velocity. D:ii-ection. Observer. 

H. m. 0 58 

1 15 

1 17 

1 19 

1 20 

1 35 

1 43 

1 54 

2 00 

2 41 

2 45 

2 47 

2 ·48 

2 52 

3 00 

3 07 

3 10 

3 12 

3 17 

3 31 

3 32 

3 34 

3 35 

3 46 

3 48 

4 03 

4 04 

4 06 

4 17 

4 31 

4 32 

4 34 

4 51 

4 52 

4 54 

4 55 

4 57 

4 58 

5 00 

5 01 

5 05 

5 15 

5 17 

5 18 

5 27 

5 29 

5 30 

5 41 

5 43 

5 45 

5 47 

5 49 

5 58 

6 00 

6 02 

6 15 

6 17 

6 19 

6 20 

6 22 

6 28 

6 31 

6 33 

6 35 

6 37 

6 43 

6 44 

6 46 

6 48 

Ft. per sec. - 2. 35 Ebb ..... R. C. Rice .... . 1. 63 ... do .......... do ........ . 1. 87 ... do .......... do ........ . 1. 75 ... do ..... : .... do ........ . 1. 75 ... do .......... do ........ . 1. 35 ... do .......... do ........ . 1. 26 ... do.~ ........ do .... : ... . 1. 53 ... do .......... do ........ . .......... .. ............. do ........ . 2. 22 Flood ........ do ........ . 2. 39 ... do .......... do ........ . 2. 19 ... do .......... do ........ . 2. 35 ... do .......... do ........ . 2. 35 ... do .... : ..... do ........ . 2. 52 ... do .......... do ........ . 2. 13 ... do .......... do ........ . 2. 35 ... do ........... do ........ . 2. 43 ... do .......... do ........ . 2. 39 ... do .......... do ........ . 2. 18 ... do .......... do ........ . 3. 08 ... do .......... do ........ . 2. 70 ... do .......... do ........ . 2. 90 ... do .......... do ........ . 2. 97 ..• do .......... do ........ . 2. 85 ... do .......... do ........ . 3. 63 ... do .......... do ........ . 3. 43 ... do .......... do ........ . 3. 63 ... do .......... do ........ . 3. 49 ... do .......... do ........ . 3. 31 ... do .......... do ........ . 3. 25 ... do .......... do ........ . 3. 31 ... do .......... do ........ . 4. 13 ... do .......... do .. ~ ..... . 3. 72 .•. do .......... do ........ . 4. 13 ... do .......... do ........ . 3. 85 ... do .......... do ........ . 4. 20 ... do .......... do ........ . 4. 28 ... do .......... do ........ . 3. 78 ... do .......... do ........ . 3. 72 .•• do .......... do ........ . 3. 85 ... do .......... do ........ . 3. 26 ... do .......... do ........ . 3. 47 ... do .......... do ........ . 3. 41 ... do .......... do ........ . 3. 59 ... do ..... A. Taylor ..... . 3. 53 · ... do .......... do ........ . 3. 47 ... do .......... do ........ . 3. 59 .•. do .......... do ........ . 3. 31. ... do .......... do ........ . 3. 72 ... do .......... do ........ . 3. 36 ... do .......... do ........ . 3. 47 ... do .......... do ........ . 3. 65 ... do ... ; ...... do ..•...... 3. 59 ... do .......... do ........ . 3. 53 ... do .......... do ........ . 3. 53 ... do .......... do ........ . '3. 41 ... do .......... do ........ . 3. 37 ... do .......... do ........ . 3.13 ... do .......... do ........ . 3. 43 ... do .......... do ........ . 3.13 ... do .......... do ........ . 2. 80 ... do ........... do ........ . 2. 80 ... do .......... do ........ . 3. 07 ... do .......... do ........ . 2. 90 ... do .......... do ........ . 2. 75 ... do ... · ....... do ........ . 2. 47 ... do .......... do ........ . 2. 73 ... do .. ~ ....... do ........ . 2. 73 ••• do •••....... do ........ . 

Remarks. 

Rolled. 

Do. 

O.K. 

Pretty steady. 

Bumping buoy; boat swinging around • Steady; no wind · Do. 

Do. 

Do. 

Do. 

Wind up again. 

Rolled. 

Excellent; no rolling; no wind. 

Do. 

Do. 

Do. 

Do. 

Do. 

Erratic. 

Excellent. 

Do. 

Sea rolled slightly. 

Do. 

Do. 

Do. 

Excellent; sea rolled slightly. 

Do. 

Do. . Erratic; sea rolled slightly. 

Do. 

Good. 

Do. 

Sea rolled slightly. 

Good; sea rolled slightly. 
OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 

TABLE 31.-0bservations of tidal currents in Golden Gate, Sept. 12-13 and Sept. 19, 1914-Continued. 

First series-Continued. 

Date. Time. Velocity. Direction. Observer. Remarks. 

Sept. 13 

H. m. 6 57 

6 59 

7 02 

7 04 

7 05 

7 07 

7 13 

7 15 

7 22 

7 31 

7 32 

7 40 

7 56 

7 58 

8 00 

8 10 

8 12 

8 14 

8 15 

8 21 

8 24 

8 42 

8 45 

8 46. 

8 55 

8 56 

8 58 

9 00 

9 52 

9 54 

9 57 

9 58 

9 59 

10 00 

10 02 

10 04 

10 05 

10 06 

10 07 

10 22 

10 23 

10 25 

10 34 

10 36 

10 38 

10 40 

10 45 

10 47 

10 48 

10 50 

Sept. 19 10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

11 

11 

11 

17 

19 

22 

25 

28 30. 

37 

51 

53 

55 

00 

02 

04 

Ft. per sec. . 2. 79 

2. 79 

2.79 

2.57 

2.52 

2.43 

2.47 

2.47 

2.43 

1.99 

1.93 

1.93 

1. 37 

1.35 

1.32 

1.10 

1.06 

1.03 

. 85 

. 93 

. 75 

1.00 

1.01 

.85 

.69 

. 78 

. 72 

. 70 

1.04 

1. 08 

1.83 

1.32 

1.80 

1.56 

1.83 

1.95 

1.72 

1.56 

1.77 

1.79 

1.99 

1.51 

1.99 

2.12 

1.99 

1.72 

1.99 

2.17 

2.03 

2.03 

Flood.... A. Taylor ..... . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . . .. do .......... do ........ . . . . do~ ......... do ...... · .. . ... do .......... do ........ . ... do .......... do ........ . ... do ..... R. C. Rice .... . · ... do .......... do ........ . ... do ..... A. Taylor ..... . ... do .......... do .. , •..... ... do .......... do ......... 

1 

... do .......... do ........ . . ~.do .......... do .... , ... . · ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do ............ do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ............... do ........ . ...........•... do ........ . ............... do ... : .... . ............... do ........ . Ebb .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do.· ....... . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ..•...... ... do .......... do ........ . . . . do ..... R. C. Rice .... . ... do .......... do ........ . ... do .......... do ........ . ... do ..... A. Taylor ..... . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do .•....... ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . 

Excellent; very calm. 

Do. 

Do. 

Do . Do . Do . Do . Do. 

Do. 

Very calm~ 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do . Do . Do . Good. 

Do. 

Poor; sea rolled; breeze. 

Do. 

Poor; sea rolled. 

Do. 

Poor. 

Do. 

Do. 

Do. 

Fair. 

Do . 

Rolled . Brisk breeze. 

Rolled. 

Do. 

Rolled; wind. 

Do. 

Do. 

Do. 

Second series. 

5. 62 Flood ... R. C. Rice .... . 5. 26 ... do .......... do ........ . 5. 62 ... do .......... do ........ . 5. 62 ... do .......... do ........ . 5. 26 ... do .......... do ........ . 5. 26 ... do .......... do ........ . 5. 02 ... do .......... do ........ . 4. 81 ... do .......... do ........ . 5. 18 ... do .......... do ........ . 4. 95 ... do .......... do ........ . 4. 88 ... do .•........ do ........ . 4. 81 ... do .......... do ........ . 5. 35 .•. do .•........ do ........ . 

Steady. 

Do. 

Do. 

Rolled gently. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

113 
114 

Date. 

Sept. 19 

HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

TABLE 31.-0bservations of tidal currents in Golden Gate, Sept. 12-13 and Sept. 19, 19J4.:_Continued. 

Second seri~s-Continued. 

Time. Velocity. Direction. Observer. 

H. m. 11 06 

11 10 

11 25 

11 27 . 11 29 

11 35 

11 41 

11 43 

11 48 

11 51 

11 53 

11 56 

12 00 

12 21 

12 23 

13 02 

13 04 

13 10 

13 15 

13 20 

13 25 

13 30 

13 35 

13 40 

13 45 

13 55 

14 00 

14 02 

14 05 

14 15 

14 20 

14 26 

14 31 

14 32 

14 34 

14 36 

14 38 

14 40 

14 42 

14 45 

14 50 

14 55 

15 00 

15 05 

15 07 

15 10 

15 34 

15 38 

15 40 

15 45 

16 00 

16 05 

16 10 

16 25 

16 30 

16 35 

16 38 

16. 40 

16 45 

16 50 

16 55 

17 00 

17 05 

17 10 

17 15 

17 17 

17 21 

17 25 

Ft. per sec. 4. 57 Flood ... R.C.Rice ..... . 4. 57 ... do .......... do ......... . 2. 95 ... do .......... do ........ . 3. 51 ... do .......... do ........ . 3. 58 ... do .......... do ........ . 3. 26 ... do .......... do .. · ...... . 2. 30 ... do .......... do ........ . 2. 42 ... do .......... do ........ . 2. 42 ... do .......... do ........ . 2. 06 ... do .......... do ........ . 1. 98 ... do .......... do ........ . 2. 22 ... do .......... do ........ . 1. 74 ... do .......... do ...... ; .. 1. 33 ... do .......... do ........ . 1. 56 ... do .......... do ......... . 2. 62 Ebb ..... C. Leidl. ...... . 3. 33 ... do .......... do.· ....... . 3. 58 ... do .......... do ... · ..... . 3. 51 ... do .......... do.: ...... . 4. 00 ... do .......... do ........ . 4.16 ... do .......... do ........ . 4.16 ... do .•........ do ........ . 4. 57 ... do .......... do ........ . 3. 88 ... do ........•. do ........ . 4. 77 ... do .......... do ........ . 4. 44 ... do .......... do ........ . 5. 82 ... do .......... do ..•...... · 5. 82 ... do .......... do •.•...... 5. 92 ... do..... R. C~ Rice ... .. 6. 74 ... do .......... do ........ . 7. 68 ... do .......... do ........ . 5. 62 ... do .........• do ........ . 6. 74 ... do .......... do ........ . 6. 13 ... do ........•• do ........ . 6. 24 ... do .......... do .•....... 6. 61 ... do ........•. do ........ . 6. 74 ... do ... · ....... do .•....... 6. 61 ... do .......... do ........ . 7. 03 ... do .......... do ........ . 6. 88 ... do .......... do ....... .. 6. 88 ... do .......... do ......... · 7. 18 ... do .......... do ........ . 6. 74 ... do ... · ....... do ........ . 6. 88 ... do .......... do ........ . 6. 61 ... do .......... do ........ . 7. 18 ... do .......... do ........ . 7. 68 ... do ..... C. Leidl. ...... . 7.18 ... do ..... R. C. Rice ... .. 7. 03 ... do .......... do ........ . 7. 10 ... do .......... do ........ . 6. 42 ... do .......... do ....... .. 6. 48 ... do .......... do ........ . 6. 24 ... do .......... do .•....... 5. 72 ... do .......... do ........ . 5. 82 ... do .......... do ........ . 5. 22 ... do .......... do ........ . 5. 35 ..• do .......... do ........ . 4. 99 ..• do .......... do ........ . 5. 10 ... do .......... do ........ . 4. 67 ... do .......... do ........ . 4. 52 ... do .......... do ........ . 4. 39 ..• do ..•....... do .•....... 4. 39 .•. do .......... do ........ . 3. 88 ..• do .......... do .•....... 4. 07 ... do .......... do ........ . 4. 31 ... do .......•.. do .•....... 3. 80 .•• do .......... do~ ...... .. 3. 59 ••• do .........• do ........ . 

Rolled gently. 

Do. 

Breeze southwest. 

Rolled gently. 

Cross currents. 

Do. 

Rolled. 

.Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Rolled; choppy. 

Rolled. 

Heavy swell. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Wind not as strong. Do,, 

Do. 

Do. 

Do. 

Rolled heavily. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Remarks. 

Rolled heavily; wind blowing hard. 

Do. · 

Do. 

Do. 
Date. 

Sept. 19 

OBSERVATIONS OF CUR.RENTS IN THE GOLDEN GAT,E. 

TABLE 31.-0bservation8 of tidal currents in Golden Gate, Sept. 12-19 and Sept. 19, 1914-Contimied. 

Time. Velocity. 

H. m. Ft. per sec. 17 30 3. 88 

17 35 3. 53 

17 40 3.01 

17 45 3.19 

17 50 3.01 

19 05 1. 71 

19 10 2. 18 

19 15 2.32 

19 20 2. 73 

19 25 3. 07 

19 35 3. 73 

19 40 4. 04 

19 45 4. 35 

20 05 4. 88 

20 10 4. 88 

20 15 4. 88 

20 20 5. 10 

20 25 5. 26 

20 30 5. 52 

20 35 5. 38 

20 40 6. 36 

20 45 6. 74 

20 50 6. 74 

20 55 6. 48 

21 00 6. 36 

21 05 6. 48 

21 10 6. 88 

21 15 5. 52 

21 20 6. 88 

21 25 6. 61 

21 30 6. 88 

21 35 5. 92 

21 40 5. 82 

21 45 5. 92 

21 55 5.92 

22 00 6. 02 

22 05 5. 82 

22 10 5. 62 

22 15 5. 72 

22 20 5. 92 

22 25 5. 92 

22 30 5. 18 

22 31 5. 62 

22 35 5. 52 

22 40 4. 98 

22 45 5. 48 

22 46 5. 48 

22 50 5. 22 

22 51 4. 99 

22 55 4. 39 

22 56 4. 52 

23 00 4. 67 

23 05 4. 48 

23 06 4. 57 

23 10 4. 99 

23 11 4. 62 

23 15 4. 31 

23 16 3. 79 

23 20 3. 86 

23 21 3. 35 

23 25 3. 26 

23 27 3. 96 

23 28 3. 44 

23 30 3. 81 

23 31 3. 65 

Second series-Continued. 

Direction. Observer. 

Ebb ..... R. C. Rice .... . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ ·. Flood ........ do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do ...•...... do ........ . ... do .......... do ........ . ... do .......... do ........ . .•. do ..•....... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do ..•....... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do ..... ~ .... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . · ... do .......... do ........ . ... do .......... do ........ . ... do ... ' ....••. do . .' ...... . ..• do .......... do ........ . ... do .........• do ........ . .•. do .......... do .•....... ... do .........• do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ......... · ... do .......... do ........ . ... do .........• do ........ . ... do ...•...... do ........ . ... do .......... do ........ . . .. do .......... d·o ........ . ... do .......... do ........ . ... do .......... do ........ . ... do ... · ....... do ........ . . . . do ••......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .•........ d9 ........ . ... do .......... do ........ . ... do .......... do ........ . ... do .......... do ........ . 

Remarks. 

Rolled heavily and pitched; wind blowing.· 

Do. 

Do . Rolled heavily and pitched; wind less. 

Rolled hea~y and pitched. Bucking buoy . 

Gentle swell; light wind. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do.· 

Tide rip caused increase. 

Rolled gently . 

(?) . 

Do. 

Do. 

Wind rising . 

115 
116 HYDRAULIC-MINING DEBR.IS IN THE SIER.RA NEVADA. 

The conditions of observation did not permit a close determination of the time of slack 

water, even forth~ division of current on which 

the boat rested. At about that time the boat 

drifted from one of its positions to the other 

and the relative motions of boat and water· 

were affected in part by the wind and by the 

heavy anchor chain. Mter a few trials the 

attempt to make direct observation of the 

time of slack water was abandoned. The 

indications of the meters never approached 

zero and the lowest velocity recorded is 0.69 

foot per second. 

The failure of the meter to record zero 

velocity when the water appeared not to 

move past the boat may have been due in 

part to subsurface current but is ascribed 

chiefly to the fact that the vanes of the meter 

are acted on not only by horizontal movement of the water but by vertical movement 

of water or meter. At all times the boat ros~ 

and fell on a swell coming in from the ocean 

and, the vertical element of the swell being 

gre~ter at the surface than at a depth of 35 

feet, there was a differential vertical motion 

between meter and water. The meter was 

suspended from the side of the boat near the 

stern and was thus subject to vertical movement whenever the boat rolled or pitched, 

and as there was much wind, and often a 

choppy sea, these movements affected many 

of the observations. They were likely to be 

strong near the change of tide, when the boat 

would swing broadside to the westerly wind. 

The influence of vertical movements of the 

meter on the measurement of the velocity of 

a current was afterward investigated by :Mr. 

Rice in the following manner: In a tidal current unaffected by wind or waves ordinary 

readings with the meter in a fixed position 

were alternated with readings when the meter 

was moved upward and downward in a manner 

to sinlulate the movements affecting observations in the Golden Gate. It was found that 

the vertical movements increased the meter 

indications by an important ratio when the 

velocities under observation were small, but 

that they did not appreciably affect the 

measurement of velocities equaling or exceeding 3 feet per second .. It is believed therefore 

that the higher determinations of velocity in 

the Golden Gate may be accepted as accurate. 

One of the noteworthy features of the observed velocities is their variability. So far 

as the lower velocities are concerned, we can 

not be sure that this was not occasioned by 

the motions of the boat, but it affected also 

the higher velocities. Among velocities greater 

than 3 feet per second there were many abrupt 

changes of 0.2 foot or more, and on 22 occasions the change occurring between o bser-

·vations from 2 to 5 minutes apart was as great 

as 0.5 foot per second. Such fluctuations indicate a turbulent current, full of rapidly 

revolving vortices, the internal velocities of 

which were combined with the general advance 

downstream, and this indication finds support in the character of the channel bed, 

. which is beset with rock ledges. 

LAG OF SLACK WATER. 

Each slack water is associated with and follows a high water or 1ow water, and I find it 

convenient to· speak of the interval of time 

between the high or low water and the following slack water as the lag of slack water. The 

determination of the lag in the present case 

involves the determination of the times of slack 

water and of the times of high water and low 

water. 

For the determination of times of slack 

water the observed velocities of current were 

plotted in relation to time, as shown in Plates 

XXX and XXXI. The ordinates for flood 

velocities were laid off above the horizontal 

axis, and the ordinates for ebb velocities below, 

the ebb velocities being treated as negative. 

It was assumed that the accelerations follow 

some simple law irrespective of the direction 

of motion, and therefore that the velocity-time 

curves above the axis should be continuous 

with those below the axis. For the data of 

September 19, a day on which the diurnal inequality, alike of tides and currents, was small, 

it was assumed that the true curve, from maximum ebb or flood velocity to the following 

maximum of flood or ebb velocity, is a cosine 

curve; and the curves were so drawn. For the 

data of September 12-13, when the diurnal 

inequality of tides was coordinate with the 

mean range of tide, the same assumption did 

not seem admissible, but the cosine curve was 

nevertheless used for purposes of trial. The 

adjustments afterward made were such that 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXX 

5 ~--~--~----~--~----~--~----~--~--~----~--~----~--~----r----r---.r---.---~----.----r--~.---.----.----.----.----1 

. . 

- 4 ~--~----+----4----~----~--~----+----+----~--~~--~----~---+----+---~-----r----r----r----r..----T----T----,_----r-~-=--r----+---~ 

. ~··/~·--~ . !y~ ~-··;\ .. 

3~~--~~--~~.~:~.~~--~~--+--+--+--+--+--+--+--+~./+-.-+-·-··+~~:~·~·~+--+--+--+--+-~ 

~~~~ -~·!/ \~. 2~-+--~~4-~·~'~~--~'~~--+---~~--~--4---~~---+---r--*---~-+--~--4~\~ __ ,_ __ +-~~~ 

:1 ~: I \ ~ .~ 7 i\ )I \! ~ 0 1-----4-~ ----+-+/ v -t-----+----+----+----4--\~+---+----+--+---+----+-----++/ ---+-----+---+---+---t-----+-\-t--\\--+--+---1 

~ -t ~4--+--/~4-----~---+----4-----~---+~.~*-----~---+----;---~~---+----;-----rl/+---+---_,-----r----+----+-----r----+----+--~,~----+----1 

~ / v.: .. ·.-: . :·::1\ . 1/ • • -~ z •• ;·: • _; •. r--

t -2 ~---+-·---4----~----+---_,----~----+---_,--r-~----+-~-~----~----+---_,--~-r----+----4-----r----+----+-----r----+----+----~·~··~+-----1 

~ \ i:· ·: -3~--~--~--+---+---+---4---4---4---~---r--~--~---+--~:~-v~-+---+---1--~--~--~~--~--~--~--+---+-~ 

\ ;· -4 ~---+----4-----~---+----4-----~---+----4-----~~-+----4-----~---+--~4-----~---+----,_----r----r----+----4----~----+----4----~--~ \ v -s~--+---4---~---+---4----~--+---+---~---+\~-+--~~-+J~--+---4---~----+--_,----r---+---~--~---+---+---4---~ \: .... / "'-· .. / .. . . ~ .. · -6~--4---~----+----+----~--~----~--~---4----+----+----~~~---4~--~---+----+----+----r---1----+----+----+----~--~---1 

-7 ~---~-----~---L----~----L-----~~-L----~---L----~----L--~~--~--~~---L----~---L--~~--~--~----~--~----~--~----~--~ 

23 0 2 3 4 7 8 9 10 II 12 10 II 12 13 14 15 16 17 18 19 20 21 22 5 6 

HOURS 

SEPTEMBER 12 SEPTEMBER 13 

OBSERV ATIOXS OF MIDSTREA1'VI VELOCITY OF CL~T lX THE GOLDEN GATE, SEPI'EMBER 12-13, 1914. 

The time scale is horizontal; the Yelocity scale vertical. Ebb velocities are represented as negative. The measurements were made with a Price meter at a station midway between Lime Point and Fort Point, • as shown in figure 21. 
U. S. GEOLOGICAL SUIWEY 

0 

z 

7 

6 

5 

4 

3 

2 

0 I () 

L&J 

(/) 

0:: 

w 

0.. 0 

tw 

w 

"-

~ -1 

>- tu 

0 

"d -2 

> 

-3 

-4 

-5 

-6 

-7 

-a 

\ 

l 

0 

0 

...J 

ll.. 

ID 

ID 

L&J 

' 

\ 

~\ .. 

\. 

\ \. 

\ 

\ . 

1\ 

\ 

\ 

\ 

1\ 

1\. 

\ 

\ 

PROFESSIONAL PAPER 105 PLATE XXXI 

... .. 

.·~ 

I ,\ 

I ""\ .. 

t \ .. 

:; :~ 

I \ 

l 

I 

/ 

I 

1/ 

I 

.l 

.V· 

I 

~ j ~ 

\ !j . / •• !';-" •• 

. • .. 9 10 II 12 13 14 15 I& 17 18 19 20 21 22 23 24 

HOURS 

SEPTEMBER 19 

OBSERVATIONS OF MIDSTREAM VELOCITY OF CURRENT IN THE 

GOLOEN GATE, SEPTEMBER 19, 1914. 

The time scale is horizontal; the velocity scale vertical. Ebb velocities are represented at~ 

negative. The measurements were made with a Price meter at a station midway between 

Lime Poii:).t ancl·Fort Point, as shown in figure 21. 
OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 117 

the line adopted is a compromise between· a 

systen1 of cosine curves, each from maximum 

velocity to maximum velocity, and a system 

of sine curves, each from zero velocity to zero 

velocity. Otherwise the curves were adjusted 

by eye to the plotted observations, the control 

being assigned mainly to the velocities greater 

than 3 feet per second. Because of the systenlatic errors of low-velocity measurements, due 

to motions of the boat, it was assumed that 

the records of low velocities were too high. · 

The intersections of the curves. with the 

horizontal axis constitute determinations of 

the times of slack water. They are listed in 

Table 32. · 

analogous to the interpretation of the velocity 

observations but on the whole less subject to 

error. The results are more accurate when the 

range. of tide is great than when it is small. 

Because the tides are on the average 4 minutes 

later at Presidio wharf than at Fort ~oint, a 

correction of -4 minutes was applied to the . \ readings. . . 

Table 32 shows the estimated lags of slack 

water, together with the times on whioh they 

are based.· A column has been added to indicate my judgment as to their relative trustworthiness. 

For the purpose of estimating. the tidal prism 

it is desired to know (1)· the general averages of 

TABLE 32.-Estinwtes of the lag of slack water in the Golden Gate. 

Date. Type of water culmination. 

Time of Time of high slack Lag of water or Relative 

low water water in slack wa- precision. Golden ter. at Fort Gate. Point. 

1914. H. m. H. m. Minutes. 

9 56 12 10 144 Poor. 

16 31 17 28 57 Good. 

23 50 1 47 117 Do. 

7 59 8 53 54 Fair. 

11 09 12 17 68 Good. 

16 46 18 29 103 Do. 

Sept. 12......... Low water ........................................ . Do .......... High water ........................................ . Sept. 12-13 ..... Low water ........................................ . 

~:~~b].~_:_:_ :_ :_ ~: ~ ~ . ~~:~~:::~· :' ~:::::::::::::: :. :::::::::::: :·:::::::::: 

The correlative data for the determination the lag of slack water after high water and low 

of the lag of slack water are the times of high water, severally, and (2) the average lags of 

water and low water. The series of observa- slack water after the several tides of the tropic 

tions from which the tidal constants of the sequence, especially the higher·high water and 

locality were computed and on which the pre- the lower low water. It 'is conceivable that if 

dictions of the Tide Tables are based were a perfect theory of tidal currents could be commade at Fort Point, a promontory of the south bined with a complete understanding of the 

coast opposite the stations for current observa- local conditions, these quantities might be ditions. · Afterward the primary tidal station rectly computed. In default of that equipwas transfeiTed from Fort Point to Presidio ment, the best available data are those assemwharf, about 1.3 miles farther east. An auto- bled in Table 32, with such concomitant facts 

matic gage is there established, producing a as are co:r1:tained in the Presidio gage record and 

marigram, or ·continuous curve of water stage, the tabulated tidal constants. Having little 

and from that record were read the times of acquaintance with the subject on the theoretic 

high water and low water on the dates of the side, I have scanned the figures gropingly in 

otuTent observations. The reading is a matter their relation to a variety of concomitant facts, 

of interpretation and judgment,. somewhat as illustrated in Table 33. 
118 HYDRAULIC-MINING DEBRIS IN ·THE. SIERRA NEVADA. 

TABLE 33 . ..,-Comparison of the lag of slack .water in th~ Golden Gate with associated data. 

-----~~--r---~----~~--~----r-~--r---~r---------.-------~--------------

1 2 

CharacteriValue zation 

of lag of as to 

slack relawater. tive 

precision. 

3 

High 

water 

or low. 

water. 

Water 

stage 

at Pre-

·sidio · 

wharf 

above 

-lower 

··low 

water. 

5 6 

Ratio 

Pr~- Follow- of p_re- cedrng -n ri ceding 

rise or rgfal~e change 

f3:ll of of t. de to f?ltide. 1 · lowrng 

change. 

8 

Duration of 

9 10 

follow-· Phase of moon Declination 

ing rise · of moon. or fall 

of tide. 

11 

Relation to tropic 

tides. 

-----------1----1 --. -. -----1------l-----l---------~l--------l-----------

Minutes. 

144 Poor .. Low .. 117 Good .... do .. 103 ... do ..... do .. 68 ... do.. High . 57 ... do ..... do .. 54 Fair ..... do .. 

Feet. 

3.75 

. 78 

1.06 

5.65 

5.45 

4.42 

Feet. 

0.31 

4.67 

4.59 

5.60 

1. 70 

3.64 

Feet. 

1. 70 

3.64 

4.69 

4.59 

4.67 

. 42 

0. 18 

1.28 

. 98 

1.22 

.. 34 

8.56 

It will be observed that column 1 of the table 

contains the estimates of lag previously shown 

in Table 32 but here arranged in the order of 

magnitude. This makes it possible to see by 

simple. inspection that none of the numerical 

data assembled in columns 4 to 8 exhibit either 

the same order of magnitudes or the inverse 

order. Cert~in elements of correlation appear, 

however, in other columns. First, the lags 

after low water are all greater than the lags 

after high water. The least of the low-water 

lags differs from the greatest of the high-water 

lags by a large amount, 35 minutes. Second, 

the contrast between low-water lags and highwater lags is greater at the time of quadrature 

(neap tides) than at new moon (spring tides). 

Third, the contrast is greater at the time of 

maximum declination (tropic tides) than at 

the time of minimum declination (equatorial 

tides). The second and third correlations are 

coincident, because the neap tides· observed 

were also tropic tides, and the spring tides were 

also equatorial. It is evident that one or the 

other of the two correlations may be accidental, 

and I judge that this is true· of the correlation 

with neap and spring tides. · The position of the 

sun affects chiefly the magnitude of tidal ranges, 

and the data in columns4, 5, and 6 indicate 

that the lag is independent of tidal range. The 

essential correlation appears to be that with 

the moon's position in relation to the plane of 

the· Equator; the difference betw:een low-water 

lag arid high-water lag is greater when the moon 

is far from the Equator. 

Minutes. 

395 Quadrature.. Maximum.. Higher low water. 

489 ..... do .......... do ....... Lower low water. 

393 New ......... Minimum .. 337 ..... do .......... do ..... .. 439 Quadrature ... Maximum .. Higher high water. 

244 ..... do .......... do ....... Lower high water. 

It would be possible to draw inferences as to 

the magnitudes of lag in relation to individual 

tides of the tropic sequence, but they would depend too largely on the weakest of all the estimates of lag. 

The direction of the moon's position when it 

is far from the plane of the Equator is the chief 

cause of the diurnal tide. The diurnal tide is · 

manifested in many ways, but most conspicuously in the· diurnal inequality of the semidiurnal tide. I find it convenient to discuss the lag 

of slack water in the Golden Gate with reference 

to the diurnal inequality of tides. That inequality is usually not greatest on the day of 

maximum lunar declination, but a few days 

later. It is usually not least at the time of zero 

declination,- hut a few days later. Therefore 

our observations, made as nearly as possible at 

the times of greatest and least declination, do 

not correspond to either the maximum or the 

minimum of diurnal inequality. They do correspond, however, to diurnal inequalities observed at the Presidio wharf on the same days, 

. and by means of that correspondence they can 

be compared with other inequalities. The inequalities with which we are specially concernedbecause we wish to know the corresponding 

slack-water lags-are (1) the mean high-water 

inequality, (2) the mean low-water inequality, 

(3) the mean high-water tropic inequality, and 

(4) the mean low-water tropic inequality. The 

mean tropic inequalities at the Presidio wharf 

aregivenin theTideTables. The mean inequality, high-water or low-water, is related to the 
OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 119 

corresponding mean tropic inequality approximately as 2 to 1r; and the Presidio values have 

been computed. 

TABLE 34.-Lag of slack water in the Golden Gate and 

diurnal inequality of tides at Presidio wharf; observations 

and inferences. 

High water. Low water .. 

Ine- Inequal- Lag. qual- Lag. 

1ty. lty. 

--------

Feet. Min. . F'eet. Min . Equatorial. ................. 0 69.2 0 96.3 

Observed Sept. 19, 1914 ....... 0. 10 68 1.01 103 

General mean ............ , ... 0.89 58.7 2.48 112.8 

Observed Sept. 12-13, 1914 .... · 1. 03 57 3.·12 117 

Mean tropic .................. 1.4 52.6 3.9 122. 1 

In Table 34 the second column contains :five 

values of the diurnal inequality of high waters, 

namely, the equatorial value (zero), the general 

mean, the mean tropic, and two observed 

values. These are arranged in the order of 

their 1nagnitude. In the third column are 

corresponding values of the lag of high-water 

slack, the second and fourth being observed 

values and the others computed. The basis of 

the computation is the assun1ption that the 

variation of the lag is (inversely) proportional 

to the vn.riation of the inequality. This assumption is not founded on theory. Having 

no knowledge of the actual law of relation, I 

have postulated the sin1plest law. 

The fourth and :fifth columns of the table 

contn.in sinlliar series of values of low-water 

diurnnl inequality and of lag of low-water 

slack. The order of magnitude is in this case 

the san1e for both columns, and the assumption 

controlling the computatjon of the first, third, 

and fifth values of lag is that the variation of 

the lu.g is directly proportioned to the variation 

of the inequality. 

The con1puted values of lag of low-water 

slack are subject to an additional qualification,. 

in that the data fron1 which they were computed 

are not ,wholly homogeneous. The lag of slack 

water observed Septen1ber 12-13 was asso ... 

ciated with a lower low water, but that obsen7ed September 19 was associated with a 

higher low water. As the purpose for which 

the lag estin1ates were sought pertains to lower 

low waters, the inharmonious datum is that of 

September 19. As the low-water inequality on 

that day was not large, it is possible that the 

lags following the two low waters did not differ· 

greatly. 

. It remains to apply a correction for river 

discharge. Whatever water the bays receive 

from other sources than tide passes out through 

the strait. It. has the effect of increasing the 

ebb currents and ebb volumes and reducing the 

flood currents and flood volumes. At change 

of tide it ,gives advantage to ebb currents, 

thereby making the epoch of high-water slack 

earlier and that of low-water slack later. 

F 

E 

FIGURE 22.-Diagram to illustrate 'the influence of discharge from rivers 

on tidal currents in the Golden Gate. 

In figure. 22 horizontal distances represent 

time and vertical distances measured from the 

line A 0 represent velocity-the mean of simultaneous velocities in the cross section of the 

Golden Gate. The positions A and 0 represent times of greatest strength of flood current 

and B represents tin1e of greatest strength of 

ebb, ebb velocities being treated as negative. 

The curve D EF indicates the progressive 

change of the velocity of tidal curre~t, and the 

points S and Tin which the curve intersects 

AO show, respe'ctively, times of high-water 

slack and low-water slack. .. The effect of adding a constant river discharge is to increase all 

ebb velocities by a certain amount and decrease 

all flood velocities by the same amount, and this 

effect may be expressed in the diagram by moving the zero of velocities from the position A 0 

to the position G I-I, the distance AG or OH. 

representing the uniform change in velocities. 

New points, 81 and 1',; now correspond to slack 

water, 8 1 being earlier than Sand T1 later than 

T. It is evident that SI and TJ, the changes 

in the times of slack water, can be computed if 

the type of curve ~nd the constants which 

afford its dimensions are known. Assuming 
120 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

that each of the two parts DE and EF is a ogy where the routes of competent theory were 

cosine curve, I have computed the time changes not apparent. 

for several sets of conditions. It is to be observed that the generalizations 

At the time of the current observations in here associated with the estimates of lag perSeptember, 1914, the river discharge measured tain only to the particular locality.. They are 

at United States Geological Survey gaging sta- not extended to other bays nor to other parts of 

tions· on streams tributary to the bays was the San Francisco Bay system. Dr. Harris has 

8,300 cubic feet per second. The average dis- pointed out to me that the tides of San Francharge at the same points is greater than this, cisco entrance have a special character which is 

and account should be taken of the difference probably related to some of the lag phenomena.· 

in correcting the estimates of lag of slack water. In general at such entrances the fall of tide ocIn a later paragraph (p. 121) the· mean dis- cupies more time than the rise, but in the 

charge at the same points is estimated at Golden Gate the mean duration of rise is 47 

43,000 cubic feet per second. Its excess above minutes longer than the duration of fall. In 

the discharge in September, 1914, is 38,000 other words, high water is there exceptionally 

cubic feet per second. To this are to be added late and low water exceptionally early. This 

an estimated discharge for unmetered land peculiarity would of itself shorten the interval· 

areas, 20,000 square miles, with an average from high water to slack water and lengthen the 

run-off of 3 inches per annum, giving 4,400 interval from low water to slack water. Percubic feet per second; and 1,900 cubic feet per haps the asymmetry of the mean tide curve 

second for rainfall on the bays and tidal should not be called a cause of the difference 

marshes. The average rainfall in the bay and between the lags of high-water slack and lowmarsh region is 20 inches per annum, and as waterslack, but the two phenomena should be 

the tide marshes are permanently saturated, regarded as concomitant results of the local contheir run-off equals the ·precipitation. An al- ditions affecting the regimen of the tides. 

lowance might also be made for evaporation RIVER-DISCHARGE DATA. 

from the water surfaces, but the rate of evaporation for September does not differ greatly In the preceding column an estimate of river 

from the mean rate for the year. discharge is used, but the basis of the estimate 

The total nontidal discharge for which cor- is not there given because its statement would 

rection is, to be made is thus 38,000 +4,400 + · interrupt the discussion of slack-water lag. 

1,900 = 44,300 cubic feet per second, a quan- The matter will now be recorded, however, for 

tity competent to produce a mean velocity in the reason that an independent interest attaches 

44 300 to the estimate and its basis. It is impractithe Golden Gate of 920,

000 0.048 foot per sec- cable to gage the flow of Sacramento and San 

ond. The corresponding corrections to the Joaquin rivers at their mouths, because there 

estimates of epochs of slack water are, for mean the rivers are tidal. The best available data on 

tide 1.40 minutes, for the slack water preaeding their discharge are derived from the gagings on 

the great tropic ebb 1.37 minutes, and for that numerous branches, made for the most part 

following the great tropic ebb 1.23 minutes. where they issue from the uplands. The reThe adopted estimates of lag are: · cords used were those of Sacramento River 

near Red Bluff, the Feather at Oroville, the 

Yuba near Smartsville, the Bear near Van 

Trent, the American at Fairoaks, the Cosumnes 

at Michigan Bar, the Mokelumne at Clements, 

the Calaveras at Jenny Lind, the Stanislaus at 

Knights Ferry, the Tuolumne near La Grange, 

the Merced near Merced Falls, the San Joaquin 

near Friant, Cache Creek at Yolo, and Putah 

Creek at Winters. From these records were 

compiled the total discharge for seven seasonal 

years, each year beginning on October 1. 

Average lag of slack water in the Golden Gate. 

Minutes. 

After all high waters........... . . . . . . . . . . . . . . . . . . . . . 57 

After all low waters ................................ 114' 

After tropic higher high waters....................... 51 

After tropic lower low waters ......... , ............. 123 

The discussion leading to these estimates is 

far from satisfactory. It. was actuated by a 

pressing need for th~ estimates, and this need 

prompted me to follow paths of uncertain anal-
OBSERVATIONS OF CURRENTS IN THE GOLDEN GATE. 121 

As a seven-year record is too short to give a 

trustworthy estimate of average discharge, I 

compared the discharge data with the precipitation records of stations at which ·observations have been made for periods of 15 to 50 

years, selecting a group of stations in the Sierra 

Nevada, another group in the dTainage· basin of 

the upper Sacramento, and a third group to 

represent the Coast Range catchment areas of 

Cache and Putah creeks. For each station the 

Weather Bureau reports give precipitation by 

seasonal years and also the general mean or 

normal. For each of the selected stations and 

for each seasonal year represented in the discharge data I computed the ratio of the year's 

precipitation to the normal; and then for each 

ye~r I derived a composite ratio in the making 

of which the data of the Sierra, Sacramento, 

and Coast Range groups were weighted as 

23:10:1, that being the approximate proportion 

in which those regions contribute to the total 

discharge. 

The data thus assembled are as follows: 

'l'ADLE 35.-Discharf!emeasured at gaging stations and ratio 

of precip~tation in the same regions. 

Seasonal year. 

1905-6 ...................... . 1906-7 ...................... . 1907-8 ...................... . 1908-9 ...................... . 1909-10 ..................... . UH0-11 ..................... . 1911-12 ..................... . 

Metered Composite 

discharge ratw of 

(cubic feet precipitaper second). tion. 

58,400 

72,000 

26,600 

61,500 

39, 700 

58,100 

20,000 

1. 21 

1.34 

. 67 

1. 19 

. 94 

1. 27 

. 56 

'fhese data were first plotted on ordinary 

section paper, and it was seen that the line to 

best represent their law must be a curve. 

They were then plotted on logarithmic paper, 

when it appeared that their law could be fairly 

well represented by a straight line. The data 

are not, however, sufficiently harmonious to 

demonstrate their law. The best representative straight line on logarithmic paper gives 

the equation Q =45,400P1.4

t, where Q is the 

metered discharge or run-off and P the ratio 

of annual precipitation to mean precipitation. 

The constant, 45,400 cubic feet per second, is 

the run-off corresponding to mean precipitation. This is· not identical with mean run-off, 

which, from the nature of the function, is somewhat greater. A computation using. the precipitation record of a single Sierra station, 

Colfax, indicated the difference as about 2 per 

cent; and this allowance yields 46,300 cubic 

feet per second as an estimate of mean discharge 

at the 14 gaging stations. 

TIDAL VOLUME. 

The discharge (in cubic feet per second) 

through the Golden Gate at any time is measured by the observed velocity (in feet per 

second), multiplied by the sectional area of the 

current (in square feet), multiplied by a 

constant. 

The constant is the ratio between the mean 

velocity of the current in the direction normal 

to the plane of section and the observed veloc-: 

ity. The observations having been made in the 

strongest part of the current the value of the 

constant is necessarily less than unity, but its 

assignment is a matter of judgment. The controlling condition is the resistance afforded by 

the bed and sides of the channel. Large values are appropriate to straight, smooth channels and relatively small valuea to rough channels. The soundings in the Golden Gate have 

been elaborate, and their record sho~ that the 

bed is very rough, being largely composed of 

rock ledges. For this reason I· make use of a 

small value, 0.75. 

The area, at half tide, of the cross section on 

the line . from Fort Point to Lime Point is 

1,035,000 square feet. There is, however, a 

section of smaller area which seems preferable 

for present use, especially as it lies nearer to 

the velocity stations. Its course is marked on 

figure 21 (p. 109) by a broken line, and its area 

is 920,000 square feet. 1 The length of the 

shorter section is 5,270 feet; of the longer, 

.5,660 feet. 

. The volume of water passing through the · 

strait during a flood or ebb tide is measured 

by ~.times the product of the discharge at· 

"strength of tide'~ by the number of seconds 

during which the tjde runs, or the period from 

slack water to slack water. If Vis the maxi1 In computing these areas I made use of details of configuration shown 

by the record of soundings but not brought out by the contours. 
122 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

mum velocity during a flood or ebb period 

(taken from the cu.r.ve in Pl. XXX or Pl. XXXI) 

and T the duration of the period in seconds, 

then the volume of the flood or ebb current, in 

cubic feet, equals 

' 2 

VTX~.75X; (920,000+c), 

the quantity c being a small correction to the 

sectional area dependent on the temporary level 

of the water surface. · 

. The data for velocity and time are sufficiently 

good to warrant the computation of volumes. 

for four ebbs and floods, given in Table 36. 

. The ranges of the corresponding rises and 

. falls at the Presidio wharf were, severally, 4.67, 

3.64, 4.59, and 4.69 feet. As the mean range 

of tide is 4 feet, it is evident that these velocities and volumes represent ordinary tides. The 

greatest 'tides have a range about twice as great 

as the mean. 

TABLE 36.-Velocit'!f, time, and volume of ebb and flood tides 

tn the Golden Gate. · 

Velocity. Time. Volume. 

Feet per 

second. Seconds. Cubic feet. Ebb Sept. 12-13 .. 5. 7 29,940 74,390,000,000 Flood Sept. 13 ..... 3.6 25,920 41,030,000,000 Ebb Sept. 19 ..... 7. 1 22,320 68,950,000,000 Flood Sept. 19 ..... 6.5 [22, 380] 64,570,000,000 
APPENDIX B.-THE TIDAL PRISM OF TIDAL MARSHES. 

OBSERVATIONS IN RAVENSWOOD SLOUGH. 

Ravenswood Slough drains a tract of tide 

· marsh bordering the southwest shore of San 

Francisco Bay near its south end. The locality was selected for special study because 

marsh and slough are still in their natural 

state, because a tract of marsh is there served 

by a single slough instead of by a member of 

a communicating system, and because the 

tidal range is there large . Near the mouth of 

slough then communicated with the bay by 

way of West Point Slough, fl.nd the route of 

communication was 5 miles longer than at 

high tide. Low-water conditions in Ravenswood Slough wore necessarily affected-in 

what manner was not learned-by tidal movements in West Point and Redwood sloughs. 

The marsh tract served by the portion of the 

slough above the station has an area of 2.822 

square miles or 78,660,000 square feet. It is 

FIGURE 23.-Map of Ravenswood Slough and marsh. From United States Coast and Geodetic Survey chart 5531. The marsh was surveyed in 

1898. A (broken) line has been added to show the area drained by that part of the channel above the United States Geological Survey 

observation station, the station being where the line crosses the slough. 

the slough is a branch which communicates 

through West Point Slough with Redwood 

Slough, and to avoid this complication the 

gaging station was located at a point above 

the branch. 

There was, however, a minor complication 

which was not escaped. The Coast Survey 

chart from which figure 23 is copied shows 

free communication between slough and bay 

at all stages of tide, but in 1914 the channel at 

the mouth had been so modified as no longer 

to remain open at the lowest stages. The 

bounded on the south by an alluvial plain, 

on the west by tide lands tributary to West 

Point Slough, and on the north and east by a 

belt of marsh land which the tides invade 

directly from the bay. 

At the station the channel is curved, the 

main current being thrown toward the right 

bank and the greatest depth being found to 

the right of the middle, as shown in figure 24. 

The bottom is of mud and is bare of vegetation, 

except at the banks. The width from bank to 

bank is about 355 feet. At the highest water 

123 
124 HYDRAULIC-MINING D1~BRIS IN THE SIERRA NEVADA. 

stage observed the maximum depth was 25.6 

feet, and both banks were submerged. At the 

lowest stage the width and dep.th were 287 

and 15.4 feet, respectively. The sectional 

area ranged from 5,800 to 2,560 square feet. 

Water stages were observed on a gage 

erected for the purpose. Velocities were observed with a Price current meter (No. 891). 

The chief observer was Roger C. Rice, assistant 

engineer, United .States Geological Survey. 

He was assisted by Arthur Taylor and for a 

part of the time by A. M. Gilbert and by me. 

Observations were made on 'September 25, 

1914, from 2.30 p. m. to 9.30 p. m., and a continuous series from November 16, at 11.30 

a. m., to November 17, at 3.40 p. m. The 

observations of water stage were made at 

irregular intervals but ·were sufficiently frequent to define the curve. The measurements 

of velocity w:ere made mostly at intervals of 

FIGURE ?4.-Cross profile of Ravenswood Slough at station for observations, looking bayward. Vertical scale five times the horizontal. 

The zero of the vertical scale corresponds to the zero of the tide gage. 

Horizontal lines show highest and lowest observed water levels. A, 

Principal meter station; B, special meter station. 

five minutes, but the interval was sometimes 

varied. The whole number of measurements 

in the regular series was 345. A special" set 

of observations to determin~ .times of slack 

water were made on. December 22. 

From previous experience the determinations of the meter were not regarded as trustworthy for velocities below 0.5 foot per second, 

but in this work a few measurements made of 

lower velocities appeared to be good. 

The observations are here reported only· in 

graphic form. In Plates XXXII and XXXIII 

the horizontal scale represents time. One 

vertical scale represents water stage, in feet, 

as read on the local gage. Another represents 

velocity of current in feet per second and is 

read both upward and downward from a zero 

line. The ebb velocities are. plotted above 

the line and the flood below. The two scales 

pertain to the same spaces, so that the curves 

of varying water stage and of varying velocity 

can readily be compared. A third vertical 

scale, limited to the lower parts of the diagrams, shows discharge in cubic feet per 

second. 

'The records of velocity are eminently harmonious for all but the highest velocities-so 

harmonious as to leave no question as to 

details of the curve. There is some irregularity in the records of velocities above 3 

feet per second, and this is ascribed with con.-

fidence to actual irregularity of velocity-not 

that the current as a whole was affected by 

pulsations, but that when the flow was strongest it was also most varied by whirls or vortices. As a vortex passed the meter it might 

yield a velocity greater or less than the normal. 

In the records of lower v~locities the plotted 

points give clear definition to a curve, but the . 

curve is irregular. This irregularity I ascribe 

to changes in the distribution of velocities 

within. the channel. In a curved channel the 

velocities are not arranged symmetric~lly, as 

they may be in a straight channel, but divisions or strands of the current move in somewhat different directions, as well as with different velocities. In the determination of 

these details .. momentum and frictional resistance are factors; each water stage, in combination with a particular general velocity, 

has its own system of oblique strands; and 

with progressive change of water stage and of 

general velocity the system of strands changes. 

Observation.s restricted, as ours were, to a 

single point in the channel would record the 

speed now of one strand and now of another. 

To test this explanation simultaneous observations of velocity were made at two points 

in the same cross. section. If the irregular~­

ties of the curve are due to variations of the 

general velocity, the two series of measurements· should yield parallel curves. If they 

are due to the shifting of strands, the results 

of the two series would probably not be parallel. While the regular series of measurements was in progress at a point (A, fig. 24) 

about 115 feet from the right (east) bank, a 

second meter was installed at a point (B) 

about 160 feet from the same bank, and the 

readings were made for 2.5 hours. The results 

are shown "in figure 25. It happened that the 

period chosen was not one of great irregularity ·of the main velocity curve, but the 
'lJ. S. mmLOGlCAL SUH.VEY 

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HOURS 10 II 

........ 

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............ ........ , ... 

12 13 14 

Ptl.OFESSIONAL PAPER 105 PLATE XXXII 

+ ... t:;++~ .... t ,.t '1- 0 Observed velocity 1"-t ~ 

~+ \ + Observed gage height I "" -+' ... ~ 

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(VI) (Ill) 

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SEPT. 25 SEPT. 26 1 1914 1 1914 

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\VATER STAGES, VELOCITIES, AND DISCHARGES IN RAVENSWOOD SLOUGH,· SEPTEMBER 25, 1914. 

Observations of water stage (gage height) are shown by crosses; obsei·vations of velocity of current by circles. The time 

scale is horizontal. There are three vertical scales representing, seve;ally, gage height in feet, velocity in feet per second, 

and discharge in cubic feet per second. Ebb velocities are plotted above the line of zero velocity; flood velocities below. 

The roman numerals connect individual ebbs and floods with data in .Plate XXXIV and Tables 37, 38, and 40. 
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jFLOODl i {VII} I . .. 

HOURS 10 II 12 13 14 15 16 17 18 19 20 21 22 23 0 

NOVEMBER 161 1914 MIDNIGHT 

PROFESSiONAL PAPER ios PLATE XXXIII 

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3 4 5 6 7 8 9 10 II 12 13 14 15 16 J7 16 

NOVEMBER 17 1 1914 

WATER STAGES, VELOCITIES, A..'\1) DISCHARGES IX RAVEXS"TOOD SLO"LGH, NOVEl\1BER 16-17, 1914. 

12 

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Observations of water ~e (gage height) are shown by crosses; observations of velocity of current by circles. The time scale is horizontal. There are three vertical scales representing, severally, gage height in feet, velocity in feet 

per second, and discnarge in cubic feet per second. Ebb velocities are plotted above the line of zero velocity; flood velocities below. The roman numerals connect individual ebbs and floods with data in Plate XXXIV and 

Tables 37, 38, and 40. 
THE TIDAL PRISM OF TIDAL MARSHES. 125 

comparison shows that fluctuations at the 

two stations were not strictly parallel. During the 35 minutes from 14 h. 40 m. to 15 h. 

15 m. the velocity at station B was notably 

lower than at station A by an average difference amounting to 11 per cent; and for 15 

minutes from 16 h. 05 m. to 16 h. 20 m., the 

average velocity at station B was the higher, 

with an average difference of 18 per cent. 

The results first sought in the discussion of 

the observations were discharges and their 

distribution through the tidal p~riods. Reprosen ting discharge by Q, the area of ·the cross 

section, in square feet, by a, and inean velocity 

0 

2 

2.0 

1.8 

8 1.6 

:X 

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II. 

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~u'VEs 30 40 so o 10 20 3o 40 50 o 10 20 30 40 50 o 

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HOURS 15 16 17 

FIGURE 25.-Velocities at two points in the same section or Ravenswood 

Slough Nov. 16, 1914. Observed velocities at A (fig. 24) are shown 

by circles, at B by crosses. · 

for the entire section, in feet per second, by 

Vm, we have 

Q=aVm 

V m is in strictness the mean, with reference 

to space, of the con1ponents of velocity normal 

to the plane of section. · 

Velocities were observed at a single point in 

the section, and their directions, which it was 

not practicable to observe, doubtless deviated 

somewhat from the normal. A certain amount 

of obliquity would be given by the vortical 

motion to which some. of the irregularities of 

the record have been ascribed, and also by the 

weaving of cmTent strands to which other 

irregularities are ascribed. 

In the· selection of a position for the meter, 

the aim was to measure the strongest surface 

velocity, and it is prob~}>le that if the meter 

had been kept continuously in the strongest 

current the velocity curve would be comparatively simple and smooth. The meter was not 

strictly at the surface but was submerged about 

2 feet, being suspended at the side of a small 

boat at anchor. 

A single series of velocity measurements in 

the vertical beneath the observation boat 

showed only slight changes in velocity from 

the surface downward until the bottom . was 

approached. 

Consideration was given to these several 

factors in selecting a coefficient for the reduction of observed velocity, Vo, to mean velocity, 

and also to the fact that the smooth channel 

bed afforded little frictional resistance. The 

coefficient used was 0.85, giving 

Q=0.85 aVo. 

The area of the stream's section varied with 

the stage of tide and was computed for each 

stage· by aid ·of a diagram based on a large 

. cross profile similar to figure 24. - The values of 

a were thus determined at 10-minute intervals, 

the stage values necessary for the computations being read from the water-stage curves 

in Plates XXXII and XXXIV . 

The simultaneous values of Vo were read, in 

similar manner from the velocity curve in the 

diagram, and the data were thus completed for 

the computation of discharges. The discharges at 1 0-minute intervals are plotted in 

Plates XXXII and XXXIII, and the lines 

joining thein are curves of discharge in relation 

to time. 

VOLUME. 

In the space inclosed between one of these 

curves and the line of zero discharge horizontal 

distances represent time, and vertical distances 

represent volume divided by time. An area 

. therefore represents time X volume + time, 

which is volume. H the horizontal elements 

are reckoned in seconds, to correspond with the 

time unit of the vertical elements, then the 

total area inclosed by one of the curves (and 

its zero line) represents the total volume of 

water traversing the section during the corresponding flood or ebb movement. 
126 HYDRA ULIC-J.V{INING D:EBRIS IN TH;:E SIERRA NEVADA. 

T'.11e computations of volume, however, were 

based primarily on the numerical data from 

which the curves had been plotted, and the 

curves were used chiefly in the extrapolation 

of discharges for times not covered by the o b-· 

servations. Except in the case of the flood 

tide of September 25, extrapolation applied 

only to discharges so small that the a_ssociated 

velocities could not be measured with the Price 

meter. Table 37 not only contains the cOinputed volumes but records other data pertaining to the several tides observed. 

polated times have no clajm to precision; the 

interpolated, with one exception, are thought 

to be as trustworthy as those obtained by direct 

observation. 

-To obtain the figures in the right-hand column of the lower division of the table (''mean 

depth of storage " 1 ) each tidal volume, in cubic 

feet, was· divided by the area of the marsh tract 

(including channels) in square feet. The quotient is the depth of a layer of water having the 

area of the marsh tract and the volume of the 

particular tide. 2 

TABLE 37.-Tidal data at station on Ravenswood Slough and comparative data at the Presidio wharl 

High water at High-water slack Low water at Low-water slack High water at 

station. at station. . station. at station. Presidio. 

Low water at 

Presidio. 

·Date. Above Above Gage 

Time. 

Gage Gage 

Time. 

Gage refer- refer- Time. read- read- Time. read- read- Time. Time. 

ing. ing. ing._ ing. ence ence plane. plane. 

1914. H. m. Feet. H. m. Feet. H. rri. Feet. H. m. Feet. H. m. H. m. Sept. 25 ................................................ an 00 . . . . . . . . . . . . . . . . . . . . . . . . 9 18 3. 25 

16 40 n. 85 b17 05 n. 80 -------- -------- -------- -------- 15 24 6. 25 -------- --- .. --- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a 1 00 . . . . . . . . . . . . . . . . . . . . . . . . 22 54 0. 05 

Nov. 16 n 09 12.30 n 33 12.28 ........................ -------- 9 43 6.65 ............... . 

----- - - - ----- - - - - - . -- - - - - --- --- . 19 15 2. 45 b19 20 2. 50 --- - . -- - ---- .. - - 16 28 -1. 24 

16-17 0 30 10.48 bO 35 10.46 -------- .. · .............. -------- 23 26 4.61 ........ -------- 17 . ------- ------.- ~-.----- ---- .. -. 5 43 5. 32 b5 48 5. 34 ..... -.... -.... - 4 00 2. 39 n 49 12. 62 12 10 12. 56 .... -.... -.... -.... -... - . - - . . . . . 10 25 7. 03 -... - -.. - - - - - - - -

-------------------------------- ................ a2o 30 ........ ---------------- 17 22 -1.44 

·Dec. 22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . n 04 · 6. 21 n 06 6. 21 . . . . . . . . . . . . . . . . 9 48 3. 14 

~6 34 10. 87 16. 36 10. 87 --- - --- - --- ---- . - . --- -- - - - --- - - - 15 13 5. 33 --- - ---- --- -----

Designa- Volume 

(cubic 

feet X 

10-6 ). 

Date. Type. 

tion in Pis. T" f Time of XXXII 1

.me.o Duration. 

Mean 

depth of 

storage. and begmnmg. ending. 

XXXIII. 

1914. 

Sept. ~t (;_-_-_-_-_-_-_-_-_ ._ ~:: :·:::::::::::::: Flood .... VI 

Ebb ..... III 

Nov. 16 ............ ------------------- ... do ..... II 

16-17---------------.------------ Flood .... VII 

17 ............ ------------------- Ebb ..... IV 

Flood .... v 

Ebb ..... I 

a Extrapolated with aid of record at Presidio. 

In the upper division of the table the four· 

columns at the right contain data from the selfregistering tide gage of the United States Coast 

and Geodetic Survey at the Presidio, San 

Francisco. 

As noted in the table, most of the times of 

'slack water were either interpolated or extrapolated. Only two were observed directly, by 

watching the surface of the water. The extraH. m. H. m. H. m. Feet. an 00 b 17 05 6 05 109.7 1.40 

b 17 05 a 1 00 7 55 n9.0 1.51 n 33 19 20 7 47 184.2 2.34 

b 19 20 bO 35 5 15 62.4 . 79 

bO 35 b5 48 5 13 52.8 .67 

b 5 48 12 10 6 22 178.8 2.27 

12 10· a 20 30 8 20 195.2 2.48 

b Interpolated by velocity curve. See Pl. XXXII or XXXIII. 

The low-water stage of the afternoon of November 16 differed but little from the low-water 

1 For definition of "depth of storage" see pp. 75, 130. 2 In the technical terminology of tidal phenomena the rise and fall of 

the water surface are tides and the horizontal movements (flood and ebb) 

of the water are currents. In colloquial usage the word tide is not re-

. stricted to rise and fall but is often applied to currents. Having frequent 

occasion to speak of the entire flood or ebb movement, from one slack to 

the next, as a unit, and discovering no appropriate technical term, I 

have found it; convenient to call it a tide. The context usually distin· 

guishes this use of the word and prevents ambiguity. 
THR TIDAL PR:ISl\f. OF TIDAL MARSHES. 127 

staO'e of the following afternoon. At the Presidlo it was 0.2 foot higher. It is therefore 

prestnnable that in the intervening 25 hours the 

same quantities of water entered and flowed 

fr01n the slough. The measurements of the two 

flood tides of th11t period give a total volun1e 

of 241,000,000 cubic feet; the 1neasurements qf 

the two ebb ticfes give 248,100,000 cubic feet. 

'.L'he ebb volumes exce'ed the flood volumes by 3 

per cent. o 

· In 1ny judgment this discrepancy is greater 

than should be ascribed to instrumental and 

personn1 errors of ohservati_on, and I ~refer. to 

ascribe it chiefly to certam assumptwns Involved in the n1o~le of reducing the observations. 

Certain irregularities in the velocity curves 

have been explained as due to the shifting of 

current strands, so that the meter was notalways in the san1e part of the main cur:en t. 

~""or that reason it is believed that the ratw of 

the observed velocity to the mean velocity was 

not constant. Nevertheless, as no way was 

discov-ered for applying corrections, the assutuption of constancy semned the be.st practicn.hle assumption. 

Another insecure assun1ption pertains to deep 

flooding of the n1arsh. The 1narsh tract dependent for its flooding on Ravenswood Slough has 

a hard and fast boundary only on the dry-land 

side. (See fig. 23.) On other sides it adjoins 

other 1narsh tracts which receive tidewater 

either through other sloughs or else directly 

fro.m the hay. During the prev-alence of an 

over1narsh water stage ·the tracts are not distinguishable; the sheet of water is continuous. 

It is only as the stage is lowered that water partings are revealed, and ev-en then the evidence is 

not in visible crests but in the fading out of 

s1nall channels. While the stage is high it is 

not only possible for water to flow gently from 

one slough district to another, hut such transfers are known actually to occur. They probably occur on all intermarsh h~undaries that 

are reached by high water l:)arlier fron1 one side 

than :frotn the other. In 1nany places the transfers are of such volume that cross channels are 

established in which the direction of flmy normally alternates. The boundaries of the Ravens~vood Slough tract are exceptionally free 

frmn such evidence o.f cross-boundary currents, 

and this fact helped to determine its selection 

for.special duty, but we must nevertheless su~­

pose that there are ·interchanges between th1s 

71139°-17--9 

and other tracts. Evidently' the· assumption, 

till now tacitly made, that the' entire water 

1novement for the flooding ·and draining of the 

tract on November 16-17 was through· the 

slough will bear qualificatio:r;1. 

RELATION OF DISCHARGE VARIATION TO THE 

TIDAL PERIOD. 

The tidal period ~here considered is not that 

from a time of high or low water to the ~allowing time of low or high water but is the interval 

between two consecutive times of slack water. 

It is the duration of a flood or ebb tide. In 

figures 26 and 27 the curves of discharge 

already shown in Plates L~XII and L~~III 

are assembled, with certain modifications. 

The horizontal scale represents tin1e, but its 

unit, instead of being an hour, is the tidal 

period. In changing frmn the scale of hours 

each curve was compressed or stretched, but 

the area inclosed by it was not changed. To 

conserve the areas, the vertical scale was given 

a compensatory change. The ordinate of the 

new curve is not discharge but is the product 

of discharge by the ratio between the particular 

tidal period and the average tidal period. 1 The 

purpose of t~is , arrang,en1ent i~ to enable ~he 

eye to appreciate at the Sftme trme the 1:ela~1ve 

volumes of the several tides and the d1stnbu· 

tion of each volume witb.in the tidal period. 

The tide~ represented. are numbered·. from I 

to VII. 

The ebb curves (fig. 26) are evidently of two 

types. Qurves I, II, and III ascend rapidly 

to a high Inaximu1n, from which there is also 

a steep descent, and this feature is absent fro~ 

curve IV. The explanation of the high max1-

n1um is cmmected with the system of reliefs 

in the tide 1narsh. The marsh is a plain, 

nearly horizontal and traversed by a system 

of branching channels. In the n1ain, the chan· 

nels have clearly defined banks, so as to be 

sharply differentiated from the plain. The 

high-water stage preceding the ebb, which corresponds to curve IV, was below· the marshplain level.. The high waters associated with 

curves I, II, and III were above the plain, and 

they were so far above that the volun1e to be 

drained from the plain was larger . than the 

volume to be drained from channels. The 

1 'l'his statement might be q'ualiflcd by saying that a constant factor 

was included in the computations for the sake of giving the cnrves·con· 

vcnicnt proportions. 
128 HYDRAULIC-MINING DEBR.IS IN .THE SIERRA NEVADA. 

acute maximum in each of the three curves 

represents the draining of water from the 

marsh plain. The gentler slope following the 

maxnnum and the entire form of curve IV 

FIGURE 26.-Curves showing variation of ebb discharge at entrance of a 

tide marsh during a tidal period. The ordinates are proportional to 

the product of discharge by the length of the tidal period. 

represent the draining of channels. It is convenient to call the tides which carry water to 

and from the marsh plain overmarsh tides, 

and to speak of those draining only channels 

as channel tides. · 

The three curves of overmarsh tides differ 

among themselves not only in the height of 

the maximum but in the position of the point 

at which the steeply descending slope is exchanged for a gently d~scending slope. The 

greater the volume of water spread on the 

marsh plain the longer the time consumed in 

its draining away. 

The overmarsh-tide curves intf rsect the 

channel-tide curve and for the seco:ad half of 

the tidal period lie below it. This is connected 

with the' fact that each overmarsh ebb tide 

not only began with a very high water stage 

but ended with a very low stage, whereas the 

channel ebb tide began and ended with stages 

of intermediate height, and with the further 

fact that the area of water surface in the channels is less at low stages than at high. The 

last units of fall of the overmarsh tides as the 

tide goes out yield less water than the same 

units of the channel t.ides. 

Of the flood tides represented, those produc- . 

ing curves V and VI (fig. 27). were overmarsh 

tides and that of curve VII was a channel 

tide. Curve V carries a high maximum, 

analogous to that of its companion ebb (I, fig. 

26), but the maximum occurs near the end of 

the period instead of the beginning. The 

rising water invaded the channels first. and the 

marsh plain afterward. The imperfect curve 

VI, representing a tide which covered the plain 

to a smaller depth, has a lower and less acute 

maximum in the same position. 

Curve VII, representing a channel tide, 

lacks the distinctive maximum of the overmarsh tides but shows a low maximum somewhat before the middle of the period. I have 

not satisfied myself as to the cause of this 

f-------ONE TIDAL PERIOD-----~ 

;:--

/ ~ v YL 

~ ~-

f...--- "'\ ,,'"" 

~ ~ ,..__ VII 

---v ......__ 

..:..---~ ~ 

~ 

v- 1'\ -- XII 

~ ~ -.......... 

~ 

--- -

/ ~ ~ 

--- 'S!Y... 

---= - -- -......__ 

v ~ ~ 

~ 

0, -- 2 4 6 8 10 

FIGURE Z7 .-Curves showing variation of flood discharge at entrance of a 

tide marsh during a tidal period. The ordinates a · 1 proportional to 

the product of dischar~re bv the length of the tidal period. 

maximum but accept it as an observed feature. 

Whatever condition is responsible for it appears to have affected also the tide represented 

by curve V. 
THE TIDAL PRISM OF TIDAL MARSHES. . 129 

It is now proposed to deduce fron1 these 

observational data some generalized curves 

to exhibit for ebb and for flood tides, the 

sequence of discharge, or volume transfer, at 

the mouth of a tidal slough (1) for the average 

of all overmarsh tides, (2) for the average of 

all tides, (3) for the ~verage tropic tides, arid 

(4) for the average of the 30 largest tides 

of the year. In deducing these curves, it is 

convenient to n1ake use of certain results 

belonging to a later division of the appendix, 

and they will be cited in the prescn t connection without explanation. The discussion leading to them may be found on pages 135-136. 

They are: (1) The over1narsh tides are numerically about one-seventh of all the tides, 

the over1narsh ebbs .being one-seventh of the 

ebbs, and the over1narsh floods one-seventh 

of the floods. (2) The channel ebb tides 

have on the average about one-third the volmne of the overmarsh ebb tides. (3) The 

channel flood tides have on. the average about 

one-half the volume of the overmarsh flood 

tides. (4) The esti1nates of average volume 

on which the preceding statements rest make 

possible a quantitative comparison of each of 

the measured tides with the mean for its class. 

The average volume of overmarsh ebb tides 

is less than the volume of either of the observed 

overn1arsh ebbs, being about one-tenth smaller 

than the volume corresponding to curve III. 

In the region of the ma.xima, therefore, the 

position of its curve is a little below that of 

curve III. Its form, as interpreted from a 

study of the four curves, appears in figure 26 

as cw·ve VIII. 

Curve IV corresponds to a tidal volume 

greater than the average volume of channel 

ebb tides in the ratio of 10 to 7. Its form is 

assmned to be representative of the class and 

has been combined with that of curve VIII to 

obtain a cm·ve for the average of all ebb tides.· 

'l'he ratio of cmnbination, account being taken 

of the facts that the channel tides are six times 

as nun1erous as the overmarsh tides and have 

an average volume only one-third as great, is 

(7 :10) X (6 :1) X (1: 3) = 7:5. The resulting curve, 

for the average of all ebbs, is curve IX of figure 

26. 

Tropic ebb tides are dominantly of the overmars~ type, and their average volu1ne (p. 136) 

is little less than that of the overmarsh ebb 

tides. The distribution curve for the latter 

(VIII) may serve also for the tropic ebb tides. 

The tides corresponding to curves I and II 

were among the largest ebb tides of the year 

1914. The average volume of the thirty largest 

ebb tides of the year falls between the volumes 

of these two. The type curve for the thirty 

ebb tides, curve X (fig. 26) was accordingly 

based on curves I and II, with onlission of 

details supposed to be accidental. 

The · data for the discussion of flood-tide 

distribution curves are comparatively meager. 

Because curve V (fig. 27), representing the 

one fully measured overmarsh flood tide, 

coincides for the first third of the tidal period 

with curve VII, representing the one observed 

channel flood tide, the assumption was made 

that all types of overmarsh flood-tide curves 

agree as to the first part of the period. and 

differ only in respect to the maximum characteristic of the remainder of the period. 

The average volume for overmarsh flood tides 

is 'less than the volumes corresponding to curves 

V and VI, being three-fourths of the volume 

corresponding to curve VI. The distribution curve for overmarsh flood tides is assumed 

to have a maximum (curve XI) notably lower 

than that of curve VI. The average volume for chaimel flood tides is less than the 

volume corresponding to curve VII in the 

ratio of 3 to 5, but curve VII was nevertheless 

used as its representative. The distribution 

curve for the average of all flood tides (curve 

XII) was obtained by combining· curves VII 

and XI. The combination ratio, involving 

the relative frequencies and relative volun1es 

of channel and overmarsh flood tides, was 

(3:5) ~ (6:1) X (1 :2) =9:5. 

The ·average volume of tropic flood tides is 

one-sixth less than the average for overmarsh 

flood tides, and the distribution curve assigned 

to tropic floods (curve XIV, fig. 27) differs little 

from curve XI. The average volume of the 

thirty largest flood tides predicted for 191 ~ 

is one-foli!th less than the volume corresponding to curve V, and the distribution curve for 

t~e thirty tides (curve XIII) was based on 

curve V. 

The purpose of the six generalized curves 

representing the volume-time relation for all 

flood tides (XII) and all ebb tides (IX), for 

tropic flood tides (XIV) and tropic ebb tides 
130 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

(VIII), and for a group of thirty great ebb 

tides (X) and the associated flood tides (XIII) 

is to aid in the computation of the tidal volume at the Golden Gate by , showing what 

fraction of the volun1e of tide water that enters 

and leaves a tide marsh is so 1elated to the 

tidal period at the Golden Gate as to augment 

that volume. For example, if, when the 

average volume of all tides is being considered, 

it is found that. the ebb tidal period at the 

Golden Gate includes the first one-third only 

of the ebb period of a particular marsh, then 

the area covered by the left-hand third of 

curve IX is proportional to the fractional part 

of the tidal storage of the marsh which is 

effective at the Golden Gate, whereas the area 

covered by the remaining two-thirds of the 

·curve is proportional to that part of the marsh's 

storage which is not effective at ~he Golden 

Gate. 

RELATION OF TIDAL STORAGE TO THE RISE 

AND FALL OF TIDE AT THE ·MOUTH OF 

RAVENSWOOD SLOUGH. 

I have thus far treated the storage of tidal 

waters by the Ravenswood Marsh tract as a 

matter of volume, but it is convenient at this 

point to introduce a different. measure of tidal 

storage.1 To apply the Ravenswood results 

to other marsh tracts it is necessary to take 

account of relative areas, and~ arrangement 

for this is most readily made by translating 

the Ravenswood data into volume per unit 

area. The translation has been accomplished 

by dividing each volume. of storage by the 

area of the tract, including both marsh plain 

and channels. The volumes being given in 

cubic feet, the area was expressed in square 

feet (78,660,000), and the quotients are 

therefore in linear feet. ·As the divisor is a 

horizontal area, the linear quotients are vertical. Each one is an expression for average 

depth of storage on the entire tract and 1nay 

be called for brevity depth of storage. 

What has been seen of the relative volumes 

of overmarsh and channel tides serves 'to illustrate the general fact that the storage of tides 

on marshes is not proportional to range of 

.tide-the vertical ~terval between the highwater and 1ow-water stages-but depends 

largely on the relation of the high-water plane 

to the level of the marsh plain. In order to 

1 The use of the term ''tidal storage" is explained on pp. 75, 85. 

deduce from the observational data the average 

depth of storage for all tides, or the average 

depth of storage for a particular group of 

tides, it is important to know how storage is 

affected by increment to stage at different 

stages. The observations contain information on this point, but it does not lie on the 

surface. 

Each detern1ination of discharge is a determination of the volun1e by which tidal storage 

is increased (or din1inished) per second at a 

particular ti1ne. Each derived deter1nination 

of depth of storage is the increment per second to depth of storage at a particular time. 

For the same particular time there is a record 

of water stage, and this record is a n1ember of a 

series. The series of sta:ge records, taken in 

connection with their time intervals, serves to 

show how rapidly the water surface was rising 

or falling at the particular time. The sequence of changing water stage has been expressed in Plates XXXII and XXXIII by a 

curve, and the direction of the curve at the 

'point correspond~g to the particular time indicates the rate at which the water stage was 

then changing. By draw~ng a line tangent to 

the curve at the point it is possible to read off, 

in terms of. the scales of ~he diagram, the rate . 

of change of the water s·tage at the particular 

time-that is, it is possible to read directly the 

numbe~ of tide-gage or water-stage units traversed by the water surface in a unit of time, or 

the number of time units corresponding to a 

unit change of water stage. Such readings 

were actually made, the thing read being the 

number of seconds corresponding to a change 

in water stage of 1 foot. This number was then 

multiplied by the increment to depth of storage 

per second and thus was obtained the increment to depth of storage per foot of change in 

water stage. In other words, the computation gave, for a particular time and for a particular water stage, the relation between increment to depth of storage and increment to 

water stage. 

A series of such detenninations were 1nade 

for each observed flood tide and ebb tide, and 

the results were plotted in relation to gage 

height or water stage. They appear in Plate 

XXXIV as a set of curves, each of which pertains to a tide. The ebb-tide curves are distinguished by full lines, the flood-tide curves 

by broken lines. Each curve shows the rela-
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 105 PLATE XXXIV 

DEPTH IN FEET OF TIDAL STORAGE PER FOOT OF CHANGE IN STAGE OF WATER AT STATION 

0 .2 .3 4 .5 6 ·.7 .8 .9 1.0 1.1 1.2 J3r-------,_------~--------r---~--~------~------~~------~------~--------~-------r-------.--------.--------.-------, 

1.3 1.4 

12r----r----'':...:....;.''---r----+--- -r-------~ ---------- ~ : -

11 -~----r-------- !VII 1- - ---~---v __ _ 

VI --------------------

-==n=---=~ r~:.~~~-~-J:: ?}.~-~~- ~- ~-~ ~~~-~ -~ ~-~- -~~-~~~~~~~-~~~~.:.~.~.::.&-- ----------

II ,~:-~·v··· ········ / / -~~~~~~~~ /<>.:>······ ~ 

IOr-------~-------T-¥~------4-~~--~~~----~------~-+--~----~--------+---------~-------+--------~--------+-------~~-------; 

-~<;.::>····· // 

r 

w sr-------~--~+-~~----~~17~------+-------~~-------+--------~--------+---------~-------+--------~--------+-------~r--------; 

lf0~V 

~ lV# ~ 8r-----~~r~€~~r--r/~~------+-------~------r-----~------~-------+------~------4-------4-------+-------~----~ 

~ !(/ ~ 7r-------t~~~:~·r+-~~---r-------+------~r-------+-------,_-------+------~--------r-------4--------~-------~------~~------; 

vr~ 1/1 6r--ll~,,ffi~1 __ --+---~---~--~---~---+---~--~--~~--~--~--~ 

rvP/ I • 

I ; 

I • 

I : 

sr---~!~=--4---------+-------~---------+--------~--------+---------r--------+---------r--------+---------r--------1---------r--------; I 

I • 

I : 

I • 

I • I • 

I 

I • I • I: 4~--~---4---------+--------4---------+-------~~-------+---------r--------+---------r--------+--------~--------4---------r--------; :ill 

I• I: 

VI ; EVIl 

I ; 

: : I: 3L-------~--------~------~~------~--------._ ______ ~--------~--------~------~--------~------~--------~--------._ ______ ~ 

RELA.TIOX OF STORAGE OF TIDAl .. WATER BY RAVEXSWOOD :MARSH TO RISE .A..:.\'D FALL OF TIDE AT OBSERVATION STATION NEAR :MOUTH OF RAVEi\"S\VOOD 

SLOCGH. 

The Yertical scale represents water stage or gage height. The horizontal scale represents the ratio which increment to depth of storage bears to increment to water stage. The full-line curves correspond 

to ebb tides; the broken-line curYes t~ flood tides. The roman numerals connect individual ebbs and floods with data in Plates LXXII and XXXIII and in Tables 37, 38, and 40. 
THE TIDAl,. PRISM OF TIDAL MAHSHES. 131 

tion to water stage of the ratio between increJnent to depth of storage and increment to 

water stage. 

Before attmnpting a generalization of the 

curves it is necessary to consider the causes of 

certain of their characteristics and div~rsities. 

The water surface within the 1narsh tract is 

never level. During the n1ain part of each 

:flood period it slopes landward, during the 

1nain part of each ebb period it slopes hayward, 

and near the tunes of slack water it undulates 

in a 1nore or less complicated manner. Moreover, its slopes are continually changing. The 

record of changing water stage ·as it was observed near the mouth of the slough does not, 

therefore, show accurately the changes of stage 

in other parts of the tract, and the rate of 

change at the point of observation is not identical with the average rate of change for the entire tract of water. If the surface were always level the sequence of changes in storage 

during a rising tide would be identical with the 

·sequence of changes during a falling tide, except that it would follow the reverse order; and 

(so far as this factor is concerned) th~ floodtide curves of Plate XXXIV would not· differ 

from the ebb-tide curves. 

It is true in a general way that the ebb 

curves and flood curves are influenced in 

opposite ways by the water-slope factor, so 

that they tend to fall into two groups; and it 

is assumed that the position of what may be 

called the normal curve-the ideal curve uninfluenced by water slope-lies between these 

groups. 

The curves corresponding to flood tides do 

not diverge widely one from another. The 

ebb-tide curves lie close together in the region 

of the lower water stages, but between the 

6-foot and 10-foot levels they stand apart. 

Curve I, which lies farthest to the right, 

corresponds to the ebb tide following the 

highest of the high waters, and the order 

of the four curves from right to left-1, II, 

III, IV -is also the order of the high waters 

with which they are associated. It will be 

noted also that as the curves ascend from the 

6-foot level the first to swing to the right is 

curve I, and then successively cwves II and 

III, while curve IV does not leave the vicinity 

of the flood-tide curves. These peculiarities 

are ·connected with the fact that curve IV 

alone corresponds to a channel tide, while 

curves III, II, and I correspond to overmarsh 

tides of successively increasing magnitude. 

The divergence of the curves is thus correlated 

with the draining away of the overmarsh 

water. The flow of that water was retarded 

by vegetation, so that the arrival of the water 

at the inouth of the slough was delayed; and 

the effect of this delay was greater and more 

prolonged as the body of overmarsh· water 

was greater. As the time sequence of the ebbtide curves is from high stage to low stage, the 

relative prolongation of the effect carries the 

aberration of the curve to a relatively low level. 

(Compare the corresponding and similarly numbered curves in fig. 2 7.) 

As .the curves ascend toward their upper 

limits, special features of striking character 

appear. All the ebb curves are reflexed to 

the left, returning quickly to the axis or zero 

line and in fact crossing it, and the flood curves 

are flattened so as to extend indefinitely to 

the right. These features are connected with 

the fact that the time of slack water is not 

coincident with the time of high water but 

follows it. 

· To understand the connection, let us return 

to the definition of the ratio represented by 

the abscissas. It is the ratio, R, between D, 

the increment to the depth of storage, and S, 

the simultaneous increment to water stage: 

D R=s 

Let us call the increment to depth of storage 

positive during the flood current and negative 

during the ebb. Let us call the· increment 

to water stage positive while the stage is 

rising and negative while the stage is falling. 

If water stage as recorded in our observations 

were the mean stage for the entire tract, the 

increment to stage would always have the 

same sigD: as the increment to depth of storage, 

but because the record gives the change of 

stage at a single point of the tract only, the 

signs are not always the same. In general, 

during flood tide both D and S are positive 

and R is therefore positive, and, in general, 

during ebb tide both D and S are negative 

and R i.s therefore positive; but other relations exist during the changes from flood 

to ebb and from rising to falling. High 

water is reached before slack water. At high 

water S is zero, while D is still positive and 
132 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

finite, and R is therefore infinite. Just after 

.high waterS is negative, but Dis still positive, 

and so R is negative. R has changed from 

positive to negative through infinity. Soon 

slack water is reached, when the value of Dis 

zero and R also is zero. With the beginning 

of the ebb D becomes negative and R becomes 

again positive. R has changed from negative 

to positive through zero. 

To return to the diagram, the flood ·curve 

V flattens toward the right and is' destined to 

become horizontal at plus infinity. It returns 

to the diagram from minus infinity and, crossing the zero line, becomes the ebb curve I. 

A similar series of changes belong to the end 

of the ebb tide and beginning of the flood, but 

their importance is less because the interval between low water and low-waterslack is relatively 

small. Their influence is not shown by the 

curves because our observations do not include the very low velocities of the current 

near the low-water epochs. 

These curious pranks of the curves serve to 

illustrate the fact that the analysis on which 

our computations were based failed to include 

all factors involved in the phenomena, but 

they need not be held to· discredit the results 

of the curve study so far as they pertain to the 

lower and middle water stages. The discordances referable to the noncoincidence of high 

water and slack water are not of importance below the 10-foot level. For the higher levels it is 

manifestly impossible to infer the character 

of the · generalized or normal curve from the 

distorted flood and ebb curves, and aid must 

be sought from other considerations. . 

Above the level of the marsh plain the 

rising water is bounded on three sides by the 

waters of other marsh tracts which are also 

ns1ng. If they rise at the same rate they 

constitute a barrier to retain .the water of the 

particular tract, and their effect is that of a 

vertical wall. If they rise at a different rate, 

the particular tract may receive water from 

other tracts or may part with water to other 

tracts. Such transfers affect simultaneous 

discharges at the mouth of the slough but do 

not affect to an appreciable extent the actual 

storage of tide water by the particular tract. 

It appears proper, therefore, to ignore them 

in the construction of the normal curve. So 

far as the water boundaries of the marsh 

pri~nn are concerned, the increment to depth 

of. storage exactly equals the increment to 

stage. 

On the fourth side the rising water is bounded . 

by the shore of the marsh. This has the' slope 

of the adjoining dry land, which is much 

steeper than the slope of the marsh plain. 

On the basis of these facts and inferences, 

the portion of the generalized curve corresponding to stages above the marsh plain has 

been made to slope steeply, and at its extremity the ratio it represents has been given the 

value of unity. 

The great increase of the ratio takes place 

within ·the narrow range of stage traversed 

while the water surface is· expanding across 

the gentle slopes of the marsh "plain, and the 

corresponding portion of the curve should be 

much more nearly horizontal than any other 

portion. Marsh conditions observed near the 

station while the tide was rising indicate that 

the most rapid expansion occurs between 

stages 10.6 and 11.6 feet. 

Under control of these. considerations the 

portion of the generalized (dotted) · curve in 

Plate XXXIV above the 10-foot level was 

drawn. It represents, progressively, the relation between change in depth of storage and 

rise or fall of tide, except as the factors are 

modified by slope of water surface. 

An abscissa of the curve, a horizontal line 

from one of its points to the axis of ordinates, 

representing the quotient of the increment to 

depth of storage by the coincident increTI?-ent 

to water stage, is the graphic expression of the 

differential of depth of storage with respect 

to stage. Moved upward or downward, with 

coordinate change of length, it produces a surface, and the area of that surface is the graphic 

expression of the corresponding integral. That 

is, the area covered by the curve between any 

two stages measures the depth of storage corresponding to the rise or fall of the water surface from one of the stages to the other. This 

property of the diagram affords a check on its 

general accuracy. In Table 38 depths of 

storage computed by the diagram are com-

. pared with the corresponding depths obtained 

more directly from the observations. 

For several reasons this check is of a rough 

character. For three of the seven· tides the 

low-water level was not observed at the slough 

stations but was inferred by means of comparative data from the marigram at the Presidio. 
THE TIDAL PRISM OF TIDAL MARSHES. 133 

The other low-water levels and all the highwater levels, being observed at a single point 

in the Ravenswood marsh tract, did not nece-ssarily represent the mean height of the water 

surface in the tract, but in the computations 

they were assumed to represent the mean 

height. Perhaps it would be proper to speak 

of tht;) comparison as a check on the consistency 

of two series of results obtained in different 

ways frmn the same body of data. 

'fABLE 38.-Comparison of graphic generalization on depth 

of tidal storage with individual determinations. 

Depth of storage. 

Designa- A. Computed by B. Com- A tion of Type. A-B general- puted di- 13 tide. ized rectly curves from obin Plate servations. 

XXXIV. 

--

Feet. Feet. Feet. 

I ......... Ebb ... 2.41 2.48 -0.07 0. 97 

II ........ ... do ... 2. 12 2.34 - . 22 . 91 

III. ...... ... do ... 1.61 1.51 + .10 1.07 

IV ....... ... do ... . 67 . 67 0 1.00 

v ........ Ji'lood .. 2. 24 2. 27 - . 03 . 99 

VI. ...... ... do ... 1.41 1.40 + . 01 1.01 

VII. ..... ... do ... . 83 . 79 + . 04 l. 05 

All ebbs .. ......... 6. 81 7.00 - . 19 . 97 

All floods. 4. 48 4.46 + . 02 1.00 

All tides .. ......... 11. 29 11. 46· - . 17 . 98 

A verago 

dis parity ...... ........ ........... . ......... ± . 07 a3. 4 

a Per cont. 

RELATION OF TIDAL STORAGE IN RAVENSWOOD 

MARSH TO RISE AND FALL OF TIDE AT THE 

PRESIDIO. 

In order to apply the data obtained in the 

Ravenswood marsh to the tides of other marshes 

o:f the bay system, it is necessary to deduce 

annual averages. Probably this could be accomplished by an expert in tidal theory in a 

relatively direct manner, but for the layman 

it is easier to first correlate the Rave11-swood 

observations with observations made at the 

Golden Gate. From a long series of observations at Fort Point the United States Coast 

and Geodetic Survey has derived the constants 

which are used in the prediction of tides for 

the locality, and the tidal elements of all stations in the bay region are referred to Fort 

Point as the primary station. A continuous 

record is now made at the Presidio wharf, only 

a short distance from Fort Point, and the data 

from that record have been used for correlation 

with the Ravenswood data. 

The tides have greater range in Rav~nswood 

Slough than at the Presidio, and correlation 

involves a comparison of scales. The zero of 

the gage used in Ravenswood Slough is independent of that at .the Presidio wharf, and correlation involves a comparison of zeros. 

In the Tide Tables the n1ean range of tides 

at the entrance to Redwood Slough is given 

as 1.56 times the range ~t Fort Point. At 

Cooley Landing the ratio is 1.54. For the entrance to Ravenswood Slough, which is midway 

between those points, a ratio of 1.55 may be 

interpolated. These ratios represent means. 

For individual tides the ratio is usually differ~ 

en t from the mean. 

The ranges of five tides were accurately observed at Ravenswood Slough. Comparisons 

of these ranges with ranges recorded at the Presidio illustrate the inconstancy of the ratio. 

It will be observed that the smaller ratios are 

associated with the larger ranges. 

TABLE 39.-Comparison of ranges of. tides at Ravenswood · Slough and at the Presidio wharf. 

Range at Range at Ravenswood Ratio. 

Slough . Presidio. 

Feet. Feet. 

9.85 7.89 1. 25 

8.03 5.85 1.37 

7.30 4.64 1. 57 

5. 16 2. 22 2.32 

4. 66 2. 19 2. 13 

Sum 35.00 Sum 22.79 1.54 

Some experiments in the correlation of 

scales served to show that with the use of a 

small ratio the results for the higher w·ater 

stages were made relatively consistent at the 

expense of the results for medium ·stages, 

while the reverse effect followed the use of a 

large ),'atio. A relatively small ratio, 1.40, 

was therefore chosen, because the great magnitude of storage by over:marsh tides gave 

special importance to the results connected 

with high stages. 

In the correlation of zeros, also, prime consideration was given to .data connected with 

over:marsh tides, the adjustment being that 
134 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

which reta:i,ned the ·most consistent relation 

betweei1, high-'Y~ter . p~anes · and the level of 

the marsh plain. Stage 11.5 feet on the 

Ravenswood gage was correlated with stage 

6.1 feet at Fort Point and the Presidio. 

.On this basis .the generalized curve of Plate 

XXXIV was redrawn on the scale of the Pre7 

6 

:y 

storage· due to a rise of 1 foot at the Presidio . 

is 1.4 times the change due to a rise of 1 foot 

at the Ravenswood station. "The abscissas of 

the new curve were therefore made greater 

than those of the original" in the ratio of 1.4 

to 1.0. The abscissas having been increased 

in the ratio by which the ordinates were eli-

- J -~-----//--__: ___ r-~- ---- r--- --~ ---1-:: - -- ---- --r--- ---

//~/ v v ~ 5 

', ~ r <. 

' ~- ' . ',~· 

~ / 

\ / 

JX ·~-~-7 A~-~ •. lj. 

... 

w 

w 

LL. 4 

~ 

0 

0 

iii 

w 3 0: 

0.. 

... 

<( 

w 

c 2 i= 

...... 

0 

tJ: 

19. 

~ \ /" 

.w. 

\ 

\ 

w 

J: 

0 

-1 

-2 

0 .2 .4 .6 .B 1.0 1.2 1.4 

RELATIVE FREQUENCY OF DIFFERENT LEVELS IN PREDICTIONS 

OF HIGH AND LOW WATERS 

DEPTH 1 IN FEET 1 OF TIDAL STORAGE ON RAVENSWOOD MARSH 

PER FOOT OF CHANGE OF STAGE AT PRESIDIO 

FIGURE 28.-Relation of tidal storage in Ravenswood marsh to water stage at the Presidio wharf. The vertical scale is of water stages 

at the Presidio. The vertical line marked 0 is the zero for horizontal scales. J)istances to the right cpresent the ratio of increment of 

depth of storage (Ravenswood) to increment of water stage (Presidio). Distances to the left re:;;>resent the relative frequency with which 

tidal culminations (high water or low water) occur at different levels. H. H. ,V., Higher high water; L. H. W., lower high water; 

H. L. W.,.higher low water; L. L. "r., lower low water. 

sidio gag~; giving curve IX in figure 28. The 

new curve represents the relation of depth of 

stor,age on Ra v:ens~ood marsh to rise ~nd fall 

of tide. at .the Presidio. As 1.0 foot on the Pre-

$.idiq g!1ge corre$ponds to 1.4 feet on the 

Ravenswood gage, the change in depth of 

minished, the areas were preserved; therefore the areas between the new curve and the 

axis of ordint!.tes are measures of depth of 

storage. A~ a check on the adjustments, the 

depths of storage for the seven observed tides 

were computed by the new diagram. The 
THE TIDAL PR.ISM OF TIDAL MARSHES. 135 

resulting values are shown, with comparative 

data, in Table 40. 

'!'AJH,l~ 40.-Second cornpm·ison of graJJhic generalization 

of tidal storage with individual deterrninations. 

Depth of storage.. 

Design a- A. Com- B. Computed by puted di- A tion of A-B general- rectly i3 tide. Type. izedcurve from 

for Presi- observadio gage tions. 

(fig. 28). 

Feet. Feet. Feet. 

I ......... Ebb ... 2. 71 2.48 +0.23 1. 09 

II ........ ... do ... 2.17 2.34 - .17 . 93 

III. ...... ... do ... 1. 55 1.51 + .04 1.03 

IV ....... ... do ... . 35 . 67 - . 29 . 57 

v ........ Flood. 2.42 2.27 + .15 1.06 

VI. ...... ... do ... 1. 21 1.40 - .19 . 86 

VII ...... ... do ... . 66 . 79 - .13 . 83 

All ebbs .. ........ 6.81 7.00 - .19 . 97 

All floods. ········ 4.29 4.46 - .17 . 96 

All tides .. ........ 11.10 11.46 - . 36 . 97 

Average 

disparity. ........ .......... .......... + .17 a14 

a Per cent. 

The values in this table are different from 

those obtained with the aid of the original diagram (Table 38) because the arguments were not 

the· same. The first diagram was entered with 

water stages observed in Ravenswood Slough 

at high-water slack and low-water slack, the 

second with Presidio records of high water 

and low water. The values are also less 

accordant, the present comparison showing an 

average disparity of 14 per ct:mt, while the 

previous comparison showed less than 4 per 

cent. The lack of accord is not a matter of 

surprise, because the procession of tide waves 

has opportunity for important modification in 

passing from the Golden Gate to Ravenswood 

Slough, but it serves' nevertheless to qualify 

such nu1nerical results as may rest on the 

·correlation of phenomena at the two localities. 

COMPUTATIONS OF AVERAGE DEPTH OF 

STORAGE. 

TABLE OF STORAGE DEPTH. 

Computations of the average depth of storage on Ravenswood marsh for certain classes of 

tides were made with the aid of the diagram 

reproduced in figure 28. For this pu!pose a 

table was formed showing for each tenth of a 

foot of tidal stag~ a:t .. t~e Presidio the depth of 

storage corresponding' to a fall from the particular level down to that of the stage designated, 1.6 feet. Then to obtain the storage 

corresponding to a rise or fall from any specified stage to another, the depths for the two 

stages were taken from the table and the less 

was subtracted fron1 the greater. 

CURVES OF FREQUENCY. 

If the function of depth of storage in relation 

to stage were a straight line, the depth of. 

storage corresponding to the average tide 

would not differ sensibly from the average 

depth for· all tides. Because of the strong 

curvative of the function it is necessary to 

take account of the relative frequency with 

which high tide and low tide, severally, occur 

at different levels. No attempt was made to 

determine the laws of frequency by analytic 

methods, but the frequencies for different 

levels of high water and low water were tak~n, 

by counting, from the tables of predictions for 

Fort Point. Curves were derived separately 

from the tables for 1908, 1912, 1913, and 1914 

and were found to be so similar that their 

composites were accepted as adequate for the 

purpose. 

The curves of frequency are reproduced in 

figure 28, where they are associated with the · 

curve for depth of storage. The vertical 

scale represents water level, or stage of tide, 

in feet, and has for its zero the ''plane of reference'' for tidal predictions. Toward the 

right from the vertical line marked 0 distances 

represent depth of storage, in feet, per foot of 

change of stage. Toward the left they represent relative frequency. 

The uppermost of the frequency curves, 

H. H. W., indicates that higher .high water 

may reach any level between 4.3 and 6.8 feet 

but occurs most frequently at levels midway 

between these. Lower high water, L. H. W., 

has an overlapping range, with maximum 

frequency about 1 foot lower. The frequency 

curve for all high waters, obtained by adding the ordinates of the H. H. W. and 

L. H. W. curves,. is distinguished by a broken 

line. In similar measures the frequency curve 

for all low waters was produced by adding the 

ordinates of the curve for higher low waters 

(H. L. W.) to those of the curve for lower low 

waters (L. L. W.). · 
136 HYDRAULIC-MINING DEBRIS IN TH~ SIERRA NEVADA. 

GENERAL AVERAGE. 

The method of computing the average depth 

of storage for all tides was as follows: Within 

the range of the high waters the tabulated 

depth for each stage was multiplied by the 

corresponding factor of relative frequency. 

The sum of the products was then divided by 

the sum o~ the frequency factors, giving an 

average depth of storage (H) for tidal ranges 

from the high-water stages to stage 1.6 feet. 

By the same process was next derived an average depth of storage (L) for tidal ranges from 

the low-water stages to stage 1.6 feet. (L) 

was then subtracted from (H), the remainder 

being the required average depth of storage for 

all tides. The depth obtained is 0.602 foot. 

This is greater by one-fifth than the depth of 

storage, 0.484 foot, corresponding to the range 

from mean high water to mean low water .. 

OVERMARSH-TIDE AND CHANNEL-TIDE 

AVERAGES. 

The stage at the Presidio wharf. that corresponds to the separation of overmarsh and channel tides in the Ravenswood marsh is not accurately defined by the data but is about 5.75 

feet. A line at that level (fig. 28) divides the 

area inclosed by the frequency curve for high 

water into parts that bear the ratio of 1 :6; the 

· smaller part corresponds to the overmarsh tides. 

As shown by the diagram, all high waters of 

that division belong to the group of higher high 

waters. The sequence of tides in the Golden 

Gate is such (see fig. 18, p. 'so) that each of 

the higher high waters is preceded by one of the 

higher low waters and followed by one of the 

lower low waters. These facts make it possible 

. to compute with ·fair approximation the average depths of storage for the overmarsh flood 

tides and the overmarsh ebb tides. As the 

average depths of storage for all flood tides and 

for all ebb tides are known (being the same as 

for all tides), the average depths of the channel 

floods and channel ebbs are readily found. 

Average depth of storage. 

Feet. 

Overmarsh flood tides .............................. 1. 05 

Overmarsh ebb tides ............................. 1. 37 

Channel flood tides................................ . 53 

Channel ebb tides .............................. ,.. . 47 

Channel floods bring in about one-half as 

much water as overmarsh floods. Channel ebbs 

deliver about one-third as much water as overmarsh ebbs. 

TROPIC TIDES. 

In their relation to the marshes some great 

tropic tides-that is, tides associated with the 

tropic higher high water-belong to the channel group, but the majority are overmarsh 

tides. Their average depth of storage is somewhat less than that of the overmarsh tides. 

As it varies from year to year, computations 

were made, with data from the Tide Tables, 

for four years (1908, 1912, 1914, and 1915), 

and the four-year means were adopted. They 

are, for the great tropic ebb tide, 1.27 feet; for 

the flood tide immediately preceding the great 

ebb, 0.87 foot. 

SUMMARY OF COMPUTED RESULTS. 

TABLE 41.-Depth of tidal storage, in feet, in Ravenswood 

marsh. 

Flood. Ebb. 

Average for overmarsh tides .......... . Average for channel tides ............ . Average for tropic tides ............... . Average for all tides ................. . For tide of average range ............. . 1.05 

. 53 

. 87 

. 602 

. 484 

1.37 

. 47 

1.27 

. 602 

. 484 

The relative frequency of overmarsh and 

channel high waters is as 1 to 6. 

LAG OF SLACK WATER. 

Each observation of the time of slack water 

at the Ravenswood Slough station was accompanied by an observation of the time of the 

associated high· water or low water. The slack 

came later than the high or low. Most of the 

observations of high and low water were fairly 

accurate, but all determinations of the time of 

slack water were unsatisfactory. On four occasions the slack was observed by watching the 

surface of the water, and the moment was 

selected when there appeared to be as much 

movement landward as hayward, but doubt 

remained as to the conditions below the surface. 

Five determinations were made by means of the 

plotted curves of velocity, and they involved 

interpolation through a considerable space. In 

every case the uncertainty as to the determination of lag amounts to several minutes. The 

values of the_lag, or the time elapsing from a 

high water or low water to the following slack 

water, are given in Table 42, with associated 

data. 
THE TIDAL PRISM OF. TIDAL MARSHES. 137 

TAnr,E 42.-Lag of slack ·water after high water and low water 

at Ravens·wood Slough station. 

Ratio 

between 

area of 

water 

Height surface 

of Lag of in marsh 

Date. Type of water stage. water slack tract 

water. and sec- ~tage. t.ional 

area of 

slough 

at stati.on. 

1914. MinNov. 17 Overmarsh high Feet. utes.' 

water ............ 12.56 19 13,600 

Nov. 16 ..... do ............ 12. 28 24 13,900 

Sept. 25 . .... do ............ 11.80 25 14,300 

Dec. 23 Channel high water 10. 87 2 5,800 

Nov. 17 . .... do ............ 10.46 8 4,400 

Dec. 22 Low water ........ 6.21 2 1,900 

Nov. 17 . .... do ............ 5.34 5 1,700 

Nov. 16 . .... do ............ 2.50 Small. 1,200 

The conspicuous fact brought out by' the 

tabulated data is that a group of lags decidedly 

greater than .the others are associated with 

overmarsh high waters, and for this association 

a plausible explanation is at hand. When a 

broad bay communicates with the ocean or 

other tided body of water by a very narrow 

strait the phenomena are those of the filling and 

emptying of a reservoir. Because time is required to pass water through the strait the surface in the reservoir does not rise and fall incomplete unison with the surface outside. When 

high tide is reached outside the filling of the 

reservoir is still incomplete, and the current· 

continues to set inward u1itil the snrface outside has fallen below the level of the surface 

inside; and, $imilarly, the outward current· 

through the strait continues for some time after 

the leiVel outside has begun to rise. So the 

reservoir factor occasions a delay in each reversal of current, or, in other words, causes a 

lag of slack water. This is not the only cause 

of slack-water lag, but it is a concurrent cause 

wherever the reservoir effect modifies the normal movements or the tide wave. 'When the 

tide water advancing through the sloughs of a 

marsh tract begins to flood the marsh land itself the area served becomes very large in relation to the sectional area of the serving channel, 

and the reservoir factor is then important. To 

illustrate this point I have computed the ratio 

between the water surface and sectional area 

for the several stages associated with the determinations of lag and recorded the values in 

Table 42. It will be seen that not only are the 

ratios exceptionally high for the overmarsh 

high waters, but those three ratios have the 

same sequence in magnitude as the corresponding lags. 

The inequalities among the smaller lags do 

not admit of profitable discussion, because the 

values of the lags are not greater than the uncertainties of their determination. 

The lag of slack water at slough entrances 

enters·as a datum into the computations of tidal 

volume for the sake .of which the Ravenswood 

study was made, and in order to serve the purpose values of the lag must be known or assumed for each of many marsh-serving sloughs 

and for each of several classes of high waters 

and low waters.. In developing a ·general 

scheme for the estimation of lags, those of overmarsh high waters were regarded as a class by 

themselves, but no distinctions were recognized 

between the lags of low waters and those of 

cham1el high wa~ers. Large values were 

assigned to the lags of tropic higher high waters, 

because those belong· to the overmarsh class; 

relatively small values were assigned to the lags 

of low waters; and the values for mean high 

water were made intermediate but nearer to the 

values for low water. (See fig. 29.) 

The scheme adopted takes account of several 

other factors, and especially of the length of the 

slough, or rather of the mean distance along 

water routes from the slough entrance to all 

parts of the associated marsh tract. It was observed at tlie Ravenswood station that in a 

short tributary slough slack water was sensibly 

coincident with high water and occurred before 

slack water iil the. main slough. This phenomenon is believed to illustrate a general fact with 

reference to tidal marshes, that the lag of slack 

water at slough entrances is greater for long 

sloughs than for short; and it is connected with · 

the general law that high water (or low water) 

and slack water are simultaneous at the head of 

an estuary but are· elsewhere separated'by an 

interval. Near the head the interval, or lag, 

increases with distance from the head, and in 

estuaries of moderate length-the class to which 

the marsh sloughs under consideration belong-

. the law of increase is probably continuous, so· 

that the greatest lag occurs at the entrance. In 

an estuary of great length and uniform section-
138 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

a nver channel-the theoretic limit or maxi- ' the diagram correspond severally to tropic 

mum value of the lag occurs, its measure being higher high tides, mean high tides, and low 

one-half of the period from one slack water to tides. The ordinates represent values of the 

the next, or, on the average, three lunar hours. 1 ·lag of slack water. ·The abscissas represent 

Under guidance of these general considera- mean distance of the marsh tract from the 

tions the scheme has been so developed that slough entrance, or the mean radius of the tract 

L 

ISO 

V) 

loJ 

t-

:J 100 z 

~ 

50 

0 5 10 

MILES 

- -

15 

L 

c 

D 

A 

20 

FIGURE 29.-Diagr:lm used in estimating the lag of slack water after 

high water and low water at entrances to the sloughs t:tat serve tide 

marshes. Vertical scale gives lag in minutes. Horizontal scale gives 

average distances in miles of a tide-marsh tract from the mouth of the 

slough serving it. Each curve co::responds to a group of high or low 

waters: A, Low waters; D, mean for all high waters; C, ~ean for tropic 

higher high waters. The line LL corresponds to the limiting value of 

lags, 186 minutes. 

the assigned values of lag increase systematically with an element related to slough length 

but increase at a diminishing rate so as never to 

e~ceed three lunar hours (186 minutes). This 

scheme is embodied in a graphic table, which is 

reproduced in figure 29. The three curves of 

1 See Harris, R. A., U.S. Coast and Geodetic Survey Rept. for 1897, 

pp. 334, 343. 

from the entrance as a center. In order to conform strictly to the considerations stated in 

preceding paragraphs, the mean distance represented by the abscissas should be measured 

along lines of current, but such measurement 

was found impracticable, and the simpler measurement of right-line distance was substituted. 

It is evident that the control afforded by the 

observational data, as well as by theoretic relations, is not rigid but admits great latitude in 

the drawing of the curves. Their form was 

somewhat influenced by some imperfect observations of the times of slack water in San Joaquin River at Antioch, and it was also influenced by the consideration that relatively large 

values of slack-water lag have been found to 

give relatively consistent results when used in 

the computation of tidal volume at the Golden 

Gate and other straits. 

It is easy to see that the time of slack may be 

greatly modified by the discharge of land 

streams that are tributary to a slough. Stream 

discharge, by strengthening the ebb current, 

increases the lag of the low-water slack; by 

weakening the flood current it reduces the lag 

of the high-water slack and may even give it a 

negative sign. At the times of our observations the Ravenswood Slough received no discharge from the land. 
APPENDIX C.-CO~PARISON OF SURVEYS OF THE BAR AT THE ENTRANCE TO 

'SAN FRANCISCO HARBOR. 

GENERAL STATEMENT. 

There have been three comprehensive surveys of the bar outside the Golden Gate, all 

executed by the Unit.ed States Coast and 

Geodetic Survey. '"l"he fu·st, in ·1855, was less 

detailed than the othe~·s. The second, in 1873, 

and the third, in 1900, were elaborate, each 

covering the area with a close network of lines 

of sounding. There was a less complete survey in 1884, and a small area, including the 

crest of the bar at the crossing of the main 

channel, was resurveyed in 1909. The various 

con1parative studies mentioned below made 

use of the original plots and other manuscript 

data preserved in the archives of the Coast 

Survey. 

The charts of 1855 and 1873 were compared 

by Lieut. Col. G. I-I. Mendell, United States 

Army, whose examination was p~rt of an in-

.vestigation of causes tending "to lessen the 

tidal scour on the bar of San Francisco and 

thereby decrease the depth of water on said 

bar." In his report, which was addressed (in 

1881) to the Chief of Engineers, United States 

Army/ he says: 

We have two surveys of the bar-one made in 1855 the 

other in 1873. The latter is as full as could be des~ed. The former, while sufficient for the purposes for which jt 

was made, is meager in its soundings. These two surveys 

hav? been placed on the same sheet. and corresponding 

sect1ons have been plotted and compared. This study 

justifies t)w statement that the bar has not retreated and 

that the depth on the crest has not been di~ini~hed. There are some indications of deposit on the inside, below 

the depth of 10 fathoms. Indeed, the indications are that 

the bar was smaller and the depth somewhat greater in 

1873 than in 1855. 

The want of fullness in the first chart may fairly b~ held 

to throw some doubt on these latter indications which on 

their face are not probable. It is thought, ho;ever, that 

the conclusion may be safely stated, that the bar was as 

good in 1873 as in 1855. 

In 1884 Prof. George Davidson communicated to the Geographical Society of the Pacific 

the result of an elaborate comparison of the 

charts of· 1855 and 1873 and expressed the 

1 Chief Eng. U. S. Army Ann. Rept. for 1881, pp. 2515-2524. 

general conclusion that "no perceptible change 

had taken place, or if there were it was in favor 

of better water." 

. An unpublished diagram (Boat sheet 2504) 

m the files of the Coast and Geodetic Survey 

show~ a compilation of crest-line profiles by 

NautiCal Expert J. T. Watkins based on data . ' from the surveys of 1855, 1873, and 1900. 

The profiles are longitudinal, each following 

the crest of the bar around its entire arc and ' where the crest lines are not identical in position they are coordinated by means of radii 

from a point within the arc. Their combinatio:o. in the diagram illustrates the fact that 

deposition and scour may take place on different parts of the bar at .the same ti1ne, so that 

general tendencies are best shown by a veraO'es · 

and it also indicates that the character of bth~ general change was not the same during the 

whole period from 1855 to 1900. From 1855 to 

1873 ~~e apparent general change was through 

depos1t10n, the crest of the bar receiving an 

average addition of 0.48 foot, and from 1873 

to 1900 the apparent general change was 

through scour, the crest suffering. an average 

loss of 1.07 feet; · 

As both Mendell and Davidson, although 

quoted above with reference to the bar as a 

whole, gave special attention to the crest there . ' is a real discrepancy between their results and 

the result obtained by Watkins for the same interval of time, 1855 to 1873. This discrepancy 

is connected with the fact that Watkins applied 

corrections for changes in the pfane of reference. 

All the soundings have for their zero~' the plu,ne 

of reference," which is the mean for the year of 

the lower of the two daily low tides. With 

progressive refinement in tidal observations and 

in the method of their reduction the accepted 

plane of reference has been changed from time 

to time; the plane used in 1855 was 1.0 foot 

lower than the plane now adopted, but the 

planes used.in 1873 and 1900 differed less from 

the present plan~. 2 · 

2 Letter from the tidal division, U.S. Coast and Geodetic Survey Jan 

15, 1909. • I "I 

139 
·140 HYDRAULIC-MINING DEBR.IS IN THE SIERRA NEVADA. 

The survey of 1873 was regarded by both 

Mendell and Davidson as a trustworthy record 

of the condition of the bar at that time, and 

each of them recommended resurvey after an 

interval for the purpose of discovering changes. 

It is therefore probable that the surveys of 

1884 and 1900 were followed by comparative 

studies, but if such were made I am not 

acquainted with them. The following paragraphs describe a comparison by myself of the 

charts of 1873 and 1900. 

The two charts have t.he same scale, 1:20,000. 

They agree also in the fact that the records of 

soundings are in feet. Most of the so.undings 

were made in linear series, and the lines were so 

·arranged as to intersect one another at many 

points. Wherever the depth at the same point 

is given by soundings of two lines the two measurements were independent, having been made 

at different times~. Thus the comparison of 

records at i.Iltersections affords a measure of 

precision so far as accidental errors are con-

. cerned. Such measures ·were derived from 

each chart for a tract where the depth is less 

than 5 fathoms and for another tract where the 

depth ranges from 10 fathoms to 16 fathoms. 

Table 43 gives averages of difference between 

two measurements of the same depth and also 

the corresponding probable error of a single 

measurement. It will be seen t.hat the precision obtained in 1900 was somewhat higher 

than that obtained in 1873 and that the soundings in shallow water are notably more accurate 

than those in deep water. 

TABLE 43.-Precision of soundings in surveys of the Golden 

Gate bar. 

Deduced 

Average probable 

Year of Depthpf Number difference error of a of inter- between _single survey. water: sections. two meas-:- measure- urements. ment of 

depth. 

Fathoms. Feet. Feet. 

1873 4-5 105 0. 84 ±0. 5 

1873 10-16 48 2. 08 ±1. 3 

1900 4-5 114 . 6·2 ± .4 

1900 10-16 47 1.56 ±1.0 

4-fathom bank and its surrounding slopes but 

not the Bonita Channel. The middle includes 

one-third of the crest of the bar, with the somewhat troughlike channel lying between this and 

the strait; it is limited outsiqe by the 10-fathom 

contour and inside by the 16-fathom contour. 

The southern includes the remainder of th~ bar 

crest, with its expansion into a broad bank at a 

depth of .about 6 fathoms, but does not include 

the South Channel. Their several areas are 

about 10, 16, and 18 square miles. 

In comparing one chart with the other two 

methods were employed-a method of contours, adapted to definite slopes, and a method 

Northern 

division 

Middle 

division 

FIGURE 30.-Plan of the Golden Gate bar, showing the divisions referred to in the text. The full-line contours have an interval of 2 fathoms; intermediate contours are dotted. All contours are based on 

the survey by the United States Coast and Geodetic Survey in 1900. 

of small tracts, adapted to surfaces of small or 

indeterminate slope. As a matter o~ record 

it seems desirable to describe these methods. 

Each of the "hydrographic sheets" bears 

contour lines that were drawn by hydrographers of the Coast Survey and used in the preparation of the generalized charts of smaller scale 

for the information of navigators. For the 

security of navigators it is important that the 

indication of depth .be not too great, .and this 

consideration determined the rule that each 

contour for ·a particular depth· should pass 

For the purpose of comparison the area cov- either through or below all points where that 

ered by the charts was considered in three di- depth was measured and below all points 

visions-northern, middle, and southern. (See where a less depth was measured. Because 

fig. 30.) The northern· division includes the of the accidental errors of the measurements 
COMPARISON OF SUR.VEYS OF BAR AT ENTRANCE TO SAN FRANCISCO HARBOR. 141 

the application of the rule n1akes the contours 

represent the minimmn possible depth instead 

of the most probable depth, and they misrepresent the depth by an amount which is 

greater as the discordance of measurements 

is greater. Because that discordance was 

greater in 1873 than in 1900 such contours 

tend to show somewhat smaller depths in 1873 

than in 1900. It is evident that for the estimation of changes in the configuration of the 

bar it is better to use contour lines that represent for each date of survey the most probable 

posit~ons of the actual lines of equal depth. 

These were attempted in the following manner: 

A sheet of tracing paper was laid over one of 

the hydrographic sheets and its position. was 

established by" elements of the projection. A 

depth was selected for contouring-for example, 8 fathoms, or 48 feet. Each line of soundings which included depths both greater and 

less than 48 feet was then examined. If one 

of its soundings showed exactly 48 a mark was 

1nade at that point. · If a consecutive series 

of soundings bore the number 48 a line was 

drawn through those points. If the number 

48 did not appear, but adjacent numbers were 

the one greater and the other less, a mark was 

made at the interpolated position of. 48 feet 

depth. When this work had been completed 

there appeared on the tracing paper a series 

of marks, each of which contained the infornlation afforded by a line of soundings .as to the 

position of the 8-fathom contour. Usually 

these marks were found not to fall absolutely 

in line but to occupy a belt, the belt being narrow in a region of steep slopes and wider in a 

region of low slopes. Within this belt the 

contour was then drawn as a line of simple 

flexure, the several marks of the belt being 

regarded as observations of equal weight. By 

the same p1·ocess contours for other depths 

were then drawn, and a series of .contours for 

corresponding depths were prepared on- a 

second sheet of tracing paper from the soundings of the other hydrographic sheet. The· 

contours thus drawn were, for the outer slope 

of the bar, the 6, 8, and 10 fathom; for the 

inner slope, ~he 6, 7, 8, 10, 12, 14, and 16 

fathom; and about the 4-fathom bank, the 

5-fathom. 

One transparent contour sheet was then 

placed over the other and adjusted by means 

of 'the projection lines, when changes in con-

. t 

tours between 1873 and 1900 becan1e apparent. 

Measurements were then made of the spaces 

through which contours had moved, slopes were 

computed from the vertical and horizontal relations of contours on the same sheet, and from. 

these results the vertical changes in the configuration of the bar were computed. 1 

For regions of very gentle slope, mainly summit regions, where the contour method breaks 

down, corresponding small tracts were :m·arked 

out on the transparent contour sheets, the 

sheets were placed in position over the hydrographic sheets, and a mean depth for each of 

the tracts was computed from the sounding 

records appearing within its boundaries. A 

separate mean was obtained for each line of 

soundings, and the mean of these means was 

taken to represent the tract. Thus each line of 

soundings was given the same weight, without 

reference to the number of individual sound-

. ings it contained within the tract. Each tract 

on the average included data from 7 lines of 

sounding, the number ranging from 4 to 10. 

On the 6-fathom shoal of the southern division 

of the bar there were 42 equal tracts, each 

representing a square 1,667 feet on a side, with 

an area of about one-tenth square mile. After 

their mean depths of sounding had been plotted 

the 6-fathom contour line was drawn through 

their district. On the higher part of the 

4-fathmn bank there were 18 such tracts, and 

when their mean depths had been plotted a 

contour line was drawn for the depth of 26 feet. 

Another system of tracts was arranged to 

include the crest line of the bar so far as the 

approximate position of the crest could be seen. 

These tracts were trapezoidal, with approximately equal lengths (about 3,300 feet) in the 

direction of the crest line but with unequal 

widths, being narrowest where the crest is best 

defined by the soundings. As the crest did not 

have the same position at tP.e time of the two 

surveys the lines of the tracts on the two oversheets were not identical. They were coordinated by means of radial lines, a method of 

coordination employed by Watkins in his study 

of crest lines. 

To all sounding data of the earlier chart I applied a general correction. In the original 

reduction of the observed depths allowance 

was made for the difference in level between 

1 The computations were in fact less simple than as here described,. 

It was necessary to take accotmt of a general correction· to the soundings 

of 1873, described in a later paragraph. · 
142 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

the water surface at the time and place of 

sounding and an ideal plane, the plane of reference. The level of the plane to which soundings 

were referred in 1873 was not the same as the 

'level afterward adppted. It appeared also 

fron1 a critical examination of· the records, 

made at my request by the section of tides and 

currents of the Coast Survey, that the treatment of fractions of feet was not the same in 

1873 as in 1900. Because of these two differO LEVEL OF LOW WATER 

TABLE 44.-Comparison of mean depths (in feet) of water on 4-fathom bank, 1873 and 1900. 

.Mean 

1 2 3 4 5 of 

five. 

----------

Depth in 1873 .. 24. 0 24.9 24. 5 24.5 25.2 24. 6 

Depth in 1900 .. 25. 3 24. 5 25. 1 25. 4 25. 3 25. 1 ·-------------

' Change in 

depth ... +1.3 - .4 +_.6 + .9 + .1 + .5 

2~--~----~----------~----------~----------+---------~~---------~----~ 

4 

6 

(/} 

:::E 

0 

:c 8 

1-

<( 

u.. 

·10 

12 

14 \\ \ \ 

160 2 3 

MILES 

4 5 6 

FIGURE 31.-Generalized cross profiles of the Golden Gate bar in its middle division. 

ences in the treatn1ent of the observations the 

soundings plotted on the chart of 1873 were 

not directly comparable with those on the chart 

of 1900 but needed a correction of -0.6 foot, 

and that correction was accordingly applied. 

The results of the comparison are given below. 

NORTHERN DIVISION. 

The crest of the 4-fathom bank had substantially the sa1ne position in 1900 as in 1873 

but was lower. Of thG 18 square tracts separately compared in that region the five showfug shallowest water gave the following mean 

depths: 

The mean for the 18 tracts is a gain in depth 

of 0.9 foot. On the 1narginal slopes of the 

bank, both inward and outward, there was. a 

net gain in depth, so that on the whole that 

part of the bar becan1e narrower. The estimated mean gain in depth for the whole division is 1.2 feet. 

MIDDLE DIVISION. 

In the discussion of data of the nuddle division use was made of generalized cross profiles, 

the first to be drawn being that for 1873. (See 

fig. 31.) The chief data for this profile are 

(1) the mean distances between contours as 

measured on the oversheet (see Table 45) and 
COMPARISON OF SU~VEYS OF BAR AT ENTRANCE TO SAN FRANC_ISCO HARBOR: 143 

(2) the n1ean depth of water on the crest, 

32.5 feet. The position of the 8-fathom con-

.tour of the inner slope is less definite than the 

positions of other contours because of a sigmoid inflection. In the northern part of ·its 

course the line runs parallel to other contours, 

but at the south it is turned back on itself to 

outline a subaqueous spit. The shoulder appearing at this level in the profile represents a 

compromise hetween the continuous slope at 

the north and the interrupted slope at the 

south. The m.ean distances through ~hich 

contours migrated between 1873 ~nd 1900 (see 

Table 45) were then used to plot points of the 

proflle for 1900, and the profile was drawn. 

The vertical spaces 2-et~een the profiles show 

gain or loss in depth. On the inner slope close 

to the crest (of 1873) there was a small loss in 

probable errors of the estimates of· horizontal 

change, and also, with allowance for other 

factors that need not be specified, the probable errors of the estimates of vertical change. 

The general features of the indicated changes 

are (1) erosion of the outer slope, the loss 

amounting to several feet; (2) a slight lowering 

of the crest; (3) the migration of the crest line 

toward the land, the distance traversed being 

several hundred feet; and ( 4) the erosion of the 

inner slope, the loss being greatest on the lower 

part of the slope. 

SOUTHERN DIVISION. 

Over the broad 6-fathom shoal, which is a 

prominent feature of the southern division, 

there was a general gain in depth. For the 42 

square tracts separately compared, the averTABLE 45.-Changes in the middle division of the' Golden Gate bar, 1873 to 1900. 

Contour. 

Distance 

from next 

contour 

at west. 

Feet. 

Direction of 

horizontal 

change. 

Amount of 

horizontal 

change. 

Gain in 

depth of 

water. 

Feet. 

10 fathoms, outside ..................................................... :. : L!lndward ... . Feet. 

330±40 

430±30 

650±30 

3. 0±0. 4 

4.0± .5 

6. 2± .4 

8 fathoms, outside............................................... 1, 380 ..... do ... · ... . 6 fathoms, outsi9.e...................................... ... . . . . . . . 1, 290 .... . ,.do ...... : 6 fathoms, inside ............. ·.................................. 2, 820 ·Oceanward .. . 20±60 

1, 250±100 

2,100 

360±100 

850±100 

1, 200±120 

.2± .2 

1. 7± . 2 

1.6 

1.0± .4 

2. 8± . 6 

5.0±. 7 

·8. 6±1. 5 

. 7 fathoms, inside............................................... 4, 230 ...... do ...... . 8 fathoms, inside............................................... 5, 400 ..... do ...... . 10 fathoms, inside.............................................. 6, 950 . ~ ... do ...... . 12 fathoms, inside.............................................. 4, 230 .... . do .. : ... . 14 fathoms, inside.............................................. 3, 860 ..... do ...... . 16 fathoms, inside.............................................. 2, 080 ..... do ...... . 1, 200±100 

Mean for whole division ...................................... :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. 1± . 2 

depth but everywhere else a gain. Amounts 

of gain are shown in the table. In computing 

the 1nean change for the whole division, 2.1 

feet, account was taken of the. form of the tract, 

which is relatively broad toward the ocean and 

narrow toward the Golden Gate. 

As each contour line drawn represents a 

compromise between the indications of position given by different lines of· sounding, the 

distances. of. the indicated positions from the 

line afford a rough measure of precision, and 

they were used to compute the probable eiTors 

in position of the contours. No refinement is 

possible. because the bendings ascribed to the 

contours are necessarily a matter of judgment. 

Th~ measures of precision have most meaning 

for the contours of the outer slope, the courses 

of which are relatively simple. From the 

probable errors of the contours were derived the 

71139°-17----10 

age gain was 1. 7 feet, and for the squares 

showing least water the average gain was 2.0 

feet. There was also a narrowing of the shoal, 

the outside contours moving toward the 

Golden Gate and the inside contours moving 

from the Golden Gate. ·The estimated gain 

in depth for the whole division is 1.6 feet. 

THE TOP OF THE BAR. 

The assumption usually made in the interest of safe navigation, that the crest-line depth 

is the least of the reported soundings, must in 

general give results in depth which are too 

small; errors of defect are included, and they 

are not offset by errors of excess. The method 

of the present comparison involves the untenable assumption that the mean depth for 

an area including the crest line is also the 

mean depth on the crest line and evidently 
144 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

must in general give results· in depth which 

. are too great. The second assumption is here 

preferred because its errors presumably affect 

the estimates from the two charts equally and 

therefore do not affect the differences, which 

.are the quantities sought; whereas the first0 

because of the great difficulty of tracing the 

course of the highest line across the 6-fathom 

shoal, and estimates, for the remaining five 

links were based on data of the square tracts. 

A generalized longitudinal profile of the 

crest is shown in figure 32, with indication of 

1- Northern division Middle division Southern division .w 

w 

L.. 10 

z 

I 

to. 

~ 20 

ct 

w 

1-

-

rv 

1: 

c: 

!0 

-'= I,) 

!0 

-~ 1: 

s 

v 

c: 

1: 

!0 

J:. 

(.) 

.!: 4 -fathom bank +J 

:J 

6 -fathom shoal 0 

<( CQ) 

·- c: (/) 

1873 , roc 

~30 ~!0 

~ 

0 

...J 

f900 

~ --------- -----~-----------., 1873 ---------- - /900 

40 I I I I I I I I I I I I 

0 5 10 14. 

MILES 

FIGURE 32.-Longitudinal profiles of the Golden Gate bar in 1873 and 1900. 

mentioned assumption presumably affects estimates from the two charts unequally. 

The chain of trapezoidal tracts described on 

page 141 started at the landward end of the 

4-fathom bank, followed the crest through the 

northern and middle divisions of the bar area~ 

and threw three. of its links into the southern 

division. It could not well be carried farther 

the more important changes between the dates 

of survey; and the depths for the several 

tracts, with the changes in depth, appear in 

Table 46. The tracts are also grouped with 

reference to the three general divisions of the 

bar area. The indicated changes are least in 

the middle division and greatest in the southern division. 

TABLE 46.-Estimates ojmean depth of water on crest-line tracts of the G~lden Gate bar in 1879 and 1900. 

No. of Mean Mean Change Mean 

depth, depth, gain for tract. 1873. 1900. in depth. division. 

Feet. Feet. Feet. Feet. 

1 27.9 29.1 +1.2 

2 25.7 27.2 +1.5 

3 25.3 25.6 + .3 

Northern division (4-fathom bank) .......................... 4 24.4 25.0 + .6 +0.8 5 24.4 25.7 +1.3 

6 25.8 27.3 +1.5 

7 28.1 28.0 - .1 

8 29.8 30.0 + .2 

Middle division. : .......•.........................•....... ·l 

9 31.3 30.9 - .4 l 10 31.4 32.1 + .7 

11 34.5 34.5 0 

12 33.7 33.9 + .2 +0.3 

13 32.4 33.2 + .8 

14 32.0 32.7 + .7 

15 32. 7 32. 7 0 

Southern division ..............•...............•.•..•...... ·l 

16 32.0 32.8 + .8 l 17 32.6 35.2 +2.6 

18 32.4 35.0 +2.6 

19 33.9 35.5 +1.6 +1.7 

20 34.0 36.5 +2.5 

21 35.5 36.4 + .9 

22 34.8 35.8 +LO 

General mean ........................................ .......... ........... ··········I·········· + .9 
COMPARISON OF SURVEYS OF BAR AT ENTRANCE TO SAN FRANCISCO HARJ30R. 145 

MIGRATION OF THE CREST LINE. w:hole shifting in 45 years, the average annual 

The revelation, by the generalized profiles of movement is 20 feet. With 1,125 feet as the 

the middle division of the bar, that the crest dividend, the estimate of average annual rate 

line lay farther east in 1900 than in 1873 led is 25 feet. · 

to a special study of changes in the position SUMMARY OF CHANGES. 

of the crest line, a study including the interval Between 1873 and 1900 there was a general 

of 45 years, from 1855 to 1900. gain in depth of water over'the whole area of 

The process of running a line of soundings the San Francisco bar, including not only the 

is such that certain. classes of errors, and espe- region of ~he crest but the inner and outer 

cially the errors connected wi~h re~uction to slopes. Of 22 tracts into which the crest belt 

mefm low w:ater, do not ttffect In an ~~o~tant was ~ivided for the purpose of comparison, only 

way ~he chfferenc.es between the Individual . two showed loss of depth_:_0.1 foot and 0.4 foot, 

soundmgs. The differences are, as a rule, less 

in error than the· soundings themselves. v For 

this reason a single line of soundings which 

crosses the ba1· crest, although of low precision 

as a measurement of the height of the bar, 

may show the position of the crest line somewhat definitely. In the study of the crest 

line with refm·ence to horizontal position, a 

profile was constructed from each available 

line of soundings, the position of the summit 

was inferred from the profile, and the crestline points thus determined were then plotted 

in proper horizontal relation. 

The method could be used to advantage 

only where the crest line has the most definite 

expression, and it was actually applied to 

about 3 miles of the bar, running south from 

the 4-fathom bank. In that region the crest 

line of 1900 was mapped by the data from 13 

lines of soundings, and the line of 1873 by 

data from 15 lines. Six points on the crest 

line of 1855 were determined, but they did 

not suffice for the drawing of the line. By 

reference to figure 33, where the lines and 

1873 

I 

1855 / 

...,. : 1900 I 

I 

I 

I 

I 

'I 

I 

I 

t 

I 

) . , of +,' 

\ ~ Golden Gate 

\\ / 

MAIN \ sJII1' 

-\-\ . 

I 

l 

I 

I 

\ 

' ~ ' \ 

I 

I 

(\ 

0 tMite L---L..-.;..&_---I---1 

pointS are rna pped 1 it. Will be Seen that the FIGURE 33.-Plan showing positions of ~e crest of tho Golden Gate bar 

line for 1873 is everywhere west of the line for in 1855, 1873, and 1000. The run line gives the profile in 1900; the 

broken line in 1873; the crosses in 1855. 1900, and that all determined points of the 

crest in 1855 lie west of the lines for later 

years. The lines determined for 1873 and 

1900 overlap for a distance of 2.3 miles, and 

in that space the average movement of the 

crest toward the Golden Gate was 465 feet. 

Four of the crest points of 1855 ·can be cOinpared with the crest line of 1873, and their 

average distance, measured on lines toward 

the Golden Gate, is 425 feet. Three of these 

points and one other can be compared with 

the crest line of 1900, and their average distance from that line is 1,125 feet. If the sum 

of 465 .and 425 feet is taken to represent the 

respectively-while the greatest· gains ,were of 

2.6 feet, and the average gain was 0.9 foot. The 

change in depth was small in the vicinity of the 

main ship route, a locality where the crest belt 

is exceptionally narrow, and the region of 

greatest change was the broad shoal into which 

the crest expands in approaching the South 

Channel. 

Above the outer slope of the bar there was 

a general gain in depth of several feet; the gai;n 

was greatest in the middle division and diminished . thence in both directions. Above the 

inner slope the gain in depth was probably 
146 HYDRAULIC-MINING DEBRIS fN THE SIERRA NEVADA. 

general, although a few points· bordering the water 1.3 feet. The half-sum of these, 0.9 foot, 

4-fathom bank appeared to show loss. The may be taken to represent the average probable 

region of greatest gain was that of deepest error of aline of sounding made in 1873. Simwater, the amount increasing from 2.8 feet at ilarly 0.7 foot, the half-sum of 0.4 foot and 1.0 

the 12-fathom line to 5.0 feet at the 14-fathom foot, may be taken as the average probable 

line and 8.6 feet at the 16-fathom line. error of a line of soundings in 1900. When a 

The average gain in depth for the northern change in depth at any point is inferred from a 

division was t'-2 feet, for the middle 2.1 feet, comparison of a sounding in 1900 with a soundfor the southern 1.6 feet, and for the whole area ing in 1873, the probable error of the inferred 

compared 1.7 feet. That area is a tract of change is (on the average) -J0.92 +0.72 feet 

about 44 square miles, but does not include = ± 1.2 feet. For a result which is a mean of n 

the entire bar, being limited in two directions such inferred differences the probable error 

by the limits adopted for one of the surveys.· 1 2 

It does, however, include nearly the whole of is ± ~n feet. The use of this formula gives 

the bar, so that the product of 1.7 feet by 44 :;1::0.4 foot as ·the average probable error of the 

square miles gives approximately the volu- computed change in depth in one of the small 

metric change in the bar. That product is tracts by means of which the shoaler parts of 

2,100,000,000 cubic feet, or 77,000,000 cubic the bar were compared. For the probable 

yards. . errors of the results for several of these tracts 

The outer slope of the bar was moved land- estimates were made also by an independent 

ward through a space of several hundred feet. method, and similar values were obtained. 

The inner slope was moved seaward through a The formula is not strictly applicable to the 

space which, on the average, was about the results of comparisons made by the method of 

same, but was much greater at low levels than contours, because the mode in which vertical 

at high. The crest line was moved landward·, changes were inferred from horizontal changes 

the change amounting to nearly 500 feet in the involved errors of independent character. The 

middle division and being less on the 4-fathom formula gives for the probable error of the 

bank. mean gain in depth for the middle division a 

The crest line was also moved landward in value less than ±0.1 foot, and though this 

the interval from 1855 to 1873, and in this . value is surely too small, it serves in a measure 

earlier interval of 18 years the space trans- as a check on the value ± 0.2 foot given in Table 

gressed was about the same as in the later 45, which was deduced in a different manner. 

interval of 27 years. The estimate of average gain in depth in the 

ACCIDENTAL ERRORS. southern division, depending largely on the estimates for 44 small tracts, has a probabie error 

of about ±0.1 foot. The estimate of average 

gain in depth in the northern division is less 

trustworthy, and a probable error of ± 0.3 foot 

is assigned without any attempt at actual computation. For the most general result, that 

the gain in depth over the entire bar had an 

average value of 1. 7 feet, the probable error is 

thought to be not greater than ± 0.2 foot. 

The accidental errors C?f the hydrographic 

surveys, the errors which tend to cancel out in 

the taking of averages, are probably fully 

represented in the discrepancies that appear 

where lines of sounding intersect. ·Each of 

those discrepancies is a difference between the 

indications given by two lines of sounding at 

their common point. As lines of sounding, 

instead of individual soundings, were used in 

all the comparisons of one chart with another, SYSTEMATIC ERRORS. · 

the checks at intersections may properly be Systematic errors, or such as are always or 

used to measure the general accuracy of the dominantly affected by the same sign, do not 

results of comparison so far as that accpracy is tend to cancel out in the taking of averages 

affected by accidental errors. Probable errors and are not covered by the computed "probcorresponding to certain groups of intersection able error." There is no royal road for the 

differences are given in Table 43 (p.140). The discovery of the existence of such errors; 

probable error of a line of soundings in 1873 they become known only through the method 

was for shallowest water 0.5 foot, for deepest . of hypothesis and test. Having undertaken 
COMPAIU'SON OF SURVEYS OF BAR AT ENTRANCE TO SAN FRANCISCO HARBOR. 147 

the comparison of charts because of the supposed flow of hydraulic mining debris to the 

bar, I was not prepared to find the later chart 

showing a gain in depth of water, a1~d when 

that result developed I was led to suspect the 

existence of a systematic error. My search 

for such an error was handicapped by lack of 

personal familiarity with methods of hydrographic surveying, but I was able to avail 

myseU of the expert· knowledge of the officers 

of the Coast Survey. 

'I'he method by which the horizontal relations of points of sounding were determined 

was the same in both surveys and seems adequate. It is true,_ moreover, that systematic 

errors in position could not account for the 

more important of the unexpected results of 

the comparison of charts. 

So far as appears by the record the method 

of sounding was the same on both occasions. 

It is a method so long established as to have 

been taken as a matter of course and therefore 

not specifically described in the printed code 

of instructions to hydrographers which was in 

force at the time of the two surveys. The 

sounding line should be vertical at the moment 

when the depth is read, and the tension should 

be such as to hold the oblong leaden weight 

vertical. If the line is oblique or curved, or 

if the lead lies on its side upon the bottom, the 

observation gives a depth too great. In case 

leadsmen were more faithful and efficient in 

one survey than the other the differences with 

which we are concerned might be affected in 

a "systematic" way. 

An attempt to investigate this point was 

based on the fact that it is specially difficult 

to bring the line to the vertical position when 

the course of the moving boat·is crossed by the 

direction of a strong current, and upon the 

further fact that errors from obliquity of the 

line are proportional to the depth. There is a 

tract of deep water inside the arc of the bar 

where the direction of the stronger currents 

is known; they are either toward or from the 

strait. On each chart one set of lines of sounding runs nearly parallel to the direction of the 

current, 'while another set crosses nearly at 

right angles. If full precautions for verti..: 

cality were not taken the chief errors would 

presumably occur on the crossing lines, and 

those lines would show the greater depths at 

the intersections. On the chart of 1873 I 

found within this tract 11 intersections where 

the greater depth was recorded in crossing the· 

current and .14 where the greater depth was 

recorded in following the direction of current. 

The sum of differences was 41 feet for the firstmentioned group and 40 feet for the second. 

On the chart of 1900 I found 26 intersections 

with greater recorded depths on the crosscurrent lines and 15 with greater depths on 

the along-current lines. The corresponding 

sums of differences were 57 feet and 23 feet. 

The average excess of depth obtained on the 

cross-current lines was in 1873, 0.0 foot; in 

1900, 0. 7 foot. While the data thus assembled are not so full as to yield. a positive 

conclusion, their indication is that precautions 

for verticality were less successful in 1900 

than in 1873, and in that event the exaggeration of depth was greater in 1900 than 

in 1873. I am disposed to question the value 

of this indication, because the same data 

show the average discrepancy at intersections, 

without regard to sign, to have been 3.0 feet 

in 1873 and only 1.5 feet in 19QO. The fact 

that the leadsmen of 1900 checked their work 

better at intersections does not sustain the 

inference that they were less successful in 

securing verticality. 

The water surface above the bar is subject to 

regular oscillations of at least tlu·ee kindstides, ground swell, ari.d the waves created by 

the existing wind. In the work of sounding the 

ground swell is usually ignored, but the resulting error is of the accidental type and does not 

affect averages. Wind waves are not ignored; 

the leadsman endeavors to eliminate their 

effect by referring each sounding to an ideal 

plane-the level of the water if not disturbed 

by Wind. This is a matter of judgment, and 

it is to be supposed that each leadsn1an has in 

regard to it a personal equation. It is possible 

also that the personal equation of the chief of 

party influences the practice of the leadsmen 

whose work he directs. There is thus a distinct 

possibility of systematic error in the treatment 

of wind waves, although the magnitude of the 

possible error can hardly be more than a s1nall 

fraction of a foot. 

The effects of the tidal oscillation received 

elaborate attention at the time of the surveys, 

a corr.ection being applied to each record of 

sounding for the ve~tical difference between the 

plane of reference and the height of the water 
148 HYDRAULIC-MINING DEBRIS IN THE SIERRA NEVADA. 

surface at the time and place of sounding. 

The local and temporary height of water 

surface was inferred from observations at 

tidal stations at the shore, due allowance 

being n1ade for the fact that like phases of 

the tide occurred earlier at the sounding 

stations than at the tidal stations. Unfortunately the methods of accomplishing this 

were not identical for the two surveys. The 

tide stations were differently placed, the planes 

of reference were different, and there were differences of detail in the mode of applying the tidal 

data to the reduction of the observations. As 

mentioned in an earlier paragraph, this subject 

received critical attention from a tidal expert 

of the Coast Survey, with the result that -0.6 

foot was applied as a correction to the charted 

soundings of 1873. Of this correction - 0.4 

foot pertains to the plane of reference and 

-0.2 foot to the method of reducing the observations.1 These corrections, though evidently proper, do not necessarily cover all 

sources of error. The tidal correction is so 

large, ranging from zero to 6 or 7 feet, that 

minor differences in the mode of its derivation may have noteworthy influence. 

This reyiew of the principal factors recognized as possible sources of systematic eiTor 

does not encourage the belief that the apparent 

gain in depth from 1873 to 1900, a gain having 

an estimated average value for the whole tract 

of 1. 7 feet, is illusory.. It is true that .the failure to discover adequate sources of systematic 

error has the character of negative evidence, 

but there is also evidence of more positive 

character tending to show the verity of the apparent gain. 

Mention has already been made (p. 143) of 

a submerged spit running northward from the 

flank of the 6-fathom shoal and causing an 

S-shaped inflection of the 8-fathom contour. 

The ·spit is shown by that contour on both 

charts but not in the same position. In 1900 

it was farther west than in 1873, its change of 

position harmonizing with the general change 

of position of the 8-fathom line. On the assumption that the spit is a permanent detail 

1 The basis of these corrections is ·given in a memorandum by R. A. 

Harris, attached to a letter dated Feb. 7, 1916, from the Superintendent 

of the United States Coast and Geodetic Survey to G. K. Gilbert, and a 

copy of the letter and memorandum are on file in the office of the Coast 

Survey. 

of the inner slope of the bar and is associated 

in a causal way. with a particular depth, its 

movement is confirmatory of the general inference that the inner slope was moved outward 

between 1873 and 1900. 

If the apparent general gain in depth were 

apparent only, the appearance being caused 

by a systematic error affecting all soundings 

of one survey by 1. 7 feet, the application of 

. the proper correction would· still leave great 

changes in the bar to be accounted for. It 

would· then appear that the bar crest, all 

through its acute portion, had grown toward 

the water surface, that several feet of sand 

had been eroded from the outer slope, and 

that there had been great erosion from the 

lower part of the inner slope, the depth of 

scour averaging 7 feet at the 16-foot contour. 

To my understanding it is no easier to explain 

a loss of substance by the lower slopes of the 

bar accompanied by a gain on the higher parts 

than to explain a general loss of substance 

which is greater on the slopes than on the 

crest. The question of explanation, however, 

is outside the scope of this appendix; it is considered in Chapter IX of the main text. 

Only a small part of the preceding discussion of errors applies to the estimates of horizontal migration of the bar crest. The method 

by which those es-timates were reached is one 

that furnishes no data for the computation of 

probable error. A possible source of systema tic error lies in the triangulation that gave 

horizontal control to the hydrographic mapping, but the same triangulation controlled 

also the mapping of the shore, and the agree-

~ent of shore features seems to afford a satisfactory check. A recognized source of error 

lies in the selection of the position of the summit on a profile line drawn among plotted points 

twt altogether harmonious. That is a matter 

of judgment, and judgment may be subject 

to personal equation and bias. As all the 

profiles were drawn in the same half-day they 

were presumably affected by the same personal 

equation. To guard against unconscious bias 

I plotted the three crest lines independently · 

on separate sheets, and computed that part 

of the work before bringing them together in 

the. drawing from which figure 33 is copied. 
INDEX. 

A. Page. 

Acknowledgments ............................................ 7, 96, 108 

Agriculture, debris supplled to streams by .................... 43-44,45 

in Yuba Uiver basin, estimate of debris output from ......... 43-44 

project for cooperation with hydraulic mining. . . . . . . . . . . . . . . . 106 

versus navigation .................................... ."....... 105 

views showing soil waste occasioned by...................... 44 

Albatross survey, on salinity of bay waters........................ 91 

samples from bed of San Pablo chrumel...................... 92 

American IUver, piedmont deposit ............................... ~8,48 

volume of debris lodged in upper basin....................... 47 

volume of mining debris supplied from basin ................. 39,43 

American Vnlloy, mining debris in............................... 41 

Analyses, mochanicnl, of sediment ............................... 92-93 

Antioch, dunes netu .............................................. 22,24 

observations of slack-water lag....... . . . . . . . . . . . . . . . . . . . . 138 

tonnce ncar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

Area of H.a vonswood marsh. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 

of bays ....................................................... 74,75 

of innndatodlnnds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

of 1narsh tracts ............................................... 78-79 

Attrit10n of debris in transportation by strenms .................. 49,68 

on Golden Gate bar ...................................... 91, 97, 101 

n. 

Page. 

California Debris Commission, plan and works, for improvement 

of Yuba River .................................... 52,61,65 

plan for control of floods in Sacramento Valley ............... 65-66 

regulation of hydraulic mining. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . I1, 67 

California, Great Valley of, deposition of debris on inundated lands 49-00 

describod.................................................... 14 

California Minors' Association,memorial to President of the United 

States ............................................... 12, 105 

Canyon bod clogged by mining debris, view of ................... 26,28 

in natural condition, view of. ............. · ................... 13, 26 

Canyon type of topography in western par't of SierraN evada, view 

showing ............................................. . 13 

Capacity of rivers for transportation of debris, conditions controlling .............................. ·····............... 26 

control of, by discharge ................................ 26,36,55,57 

by fineness or debris ... : .................................. 26, 53 

by ratio of depth to width of channel. ............. 26, 62, 63, 106 

by slope of bod.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26, 53 

Carquinez Strait, amount of shoaling between datos of survey ... . 32 

bed material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92-94 

ebb-current velocity ..•....................................... 83.84 

shell mound near...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

volllllle of debris deposits.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 

volume of tropic ebb current................................. 83 

Baker, S. K., map of bod of Yuba River ........................ . 58 Channel of Sacramento River, enlargement of.................... 66 

original depth to be restored ................................. 66,68 survey of bod of Yuba River ................................ . 53 

work of. ..........•.................... ·············· ........ . 

Bar across mouth of Bolinas Lagoon.............................. 69 

in Marc Island Strait •••.................................... 101-103 

outside Golden Gate. See Golden Gate bar. 

13ar, semicircular, in Evolution I~ake............................. 96 

13arrior No.1 on Yuba River, studios at ....................... 52-54,59 

diagr.arn showing changes in river profile at................... 59 

maps showing erosion below. . • • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 

views of ................................................... 52,53,60 

Bosins latoru.l to Sacrrunento River, account of. .................. 14,65 

function, as reservoirs of flood water .......................... 15,66 

1nap .•.•..................................................... 14,66 

Bays, areos or. ................................................... 74-75 

deposits of debris in .................................... 32-37,49,68 

Gil'ectivo tidal ranges ...................................... 81, 83,86 

marshes bordering. See Marshos. 

tidal volumes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81, 83 

See also names of 11articular bays. 

Beach, raised, ncar San Pablo Bay............................... 16 

13oar Hlvor, piedmont deposit .................................... 28,48 

volume of debris lodgod in uppor bosin....................... 48 

volume of mining debris suppliod from basin ................. 39,43 

Bonyamd commission, on volume of Boar River piedmont deposit 48 

on volume of mining debris .................................. 38, 42 

work of...................................................... 11 

Berkeley Hills, fault along....................................... 17 

view on ............. , ............................ ·. . . . . . . . . . . . 44 

Bolinas Lagoon bar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 

Bonita Channel, currents......................................... 71 

1nap showing................................................. 70 

Bonita Point, drift of sand past.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 

sand from beach ncar.. . . . . . . . . . . . . . . . . .. . .. .. . . .. .. . . . . . .. .. 92 

Bourn, ,V. B., acknowledgments to.............................. 7 

llradford Island, view on .................... ·..................... 19 

B y-passos, map of proposed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 

proposed, for flood waters of Sacramento River............... 65 

c. 

Callfornla Debris Commission, on flood bosins of Sacramento Valloy and capacity of river channel..................... 50 

origin und duties of. ••••..•.................................. 11-12 

shoaled by mining debris .................................. 11,29-30 

too small for flood discharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15, 50 

Channel of Yuba River, control of, by training walls ............. 62-63 

remodeled by floods .................................. : ....... 60-61 

Channel tides, average water storage by.......................... 136 

definition of.................................................. 128 

variation of discharge in relation to tidal period ........ 128, 129, 131 

Charts of Golden Gate bar, comparison of ...................... 1:m-148 

Christy, Prof. S. B., address by.................................. 12 

Clapp, C. H., on run-off of Sacramento drainage basin ............ 50,89 

Colfax, view of field near......................................... 44 

Commerce versus agriculture and hydraulic mining ............ 104-105 

Comminution of debris in transportation by streams ............. 49, 68 

on crest of Golden Gate bar .............................. 91, 97, 101 

Conservation of soil by grass, view illustrating .............. :..... 43 

Cooperation ofindustrial interests in control of streams ......... 106-107 

Co tidal lines of San Francisco Bay system........................ 72 

Current, Davidson inshore....................................... 71 

great tropic ebb ...................... ,....................... 80 

Current meters used in Golden Gate observations .............. 109,110 

in Ravenswood Slough observat.ions..... .. .. .. . . . . . . . . . . . . . . . 124 

Current observations in Golden Gate, plots of.................... 116 

in Ravenswood Slough, plots of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 

Currents at entrance to Golden Gate............................. 71 

flood and ebb, given opposite signs on diagrams ......... 77,116,124 

tidal, action of, on Golden Gate bar ...................... 96-97,100 

in Golden Gate, observat.ions of. ..•.................... 108-116 

in relation to tropic sequence of tides..................... 80 

modificati9n of, by river discharge .•.•.................. 119-120 

See also Velocity. 

Curve showing apparent change of mean sea level •••.•........... 

Curve of increment to tidal storage on Ravenswood marsh in rela20 

tion to increment of water stage at Presidio wharf.... 134 

Curve of tidal discharge, to show influence of added river discharge. 119 

Curves illustrating relative efficiencies of large and small tides 

for the transportation of debris...................... 79 

Curves of frequency of high tides and low tides at different levels. 135-136 

Curves of increment to tidal storage in relation to increment of 

· water stage... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 

Curves of lag of slack water in a tidal slough in relation to average 

distance of associated marsh tract from the slough 

entrance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 

149 
150 INDEX. 

Page. Page. 

Curves of tropic tidal oscillations and associated currents in San Discharge in channel serving tidal marsh, curve showing variation 

Francisco Bay ...................................... . 80 of ................................................... 77,128 

Curves showing fluctuations of low-water level at river stations .. 

Curves showing progressive variations of discharge in a channel 30 Discharge measurements in Ravenswood Slough, plots of......... 124 

Discharge of rivers, combination of, with tidal discharge at Golden 

serving a tidal marsh ................................ 77,128 

Curves showing variations of factors affecting rate of deposition of 

debris m the San Francisco bays .................... . 36 

Curves showing variations of tidal range 11ith distance from 

Golden Ga~e ..........................•.............. 74 

D. 

Daguerre Point dam ............................................. 61-63 

Daguerre Point, view from....................................... 52 

Dam built to arrest debris carried by Yuba River, account of. ... 52-53, 

58-59,60 

mapsof....................................................... 58 

views of. ..................................................... 52,60 

See a.lso Barrier No.1. 

Dam, proposed, at Hallett Point ............................... 106-107 

Dams to impound hydraulic mine tailings, account of............ 67 

views of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66, 67 

Davidson, George M., on inshore current .... ,.................... 71 

on change of depths on Golden Gate bar .............. 94-95, 139,140 

on ctirrents in Golden Gate................................... 90 

Davidson inshore current ....•............ ·. . . . . . . . . . . . . . . . . . . . . . . . · 71 

Debris, comminution in transit ..................... · .............. 49,68 

Debris Commission. See California Debris Commission. 

Debris, data on rate of varying delivery to bays................... 36 

deposition by flocculation •................................... 35,49 

deposits of, in bays ..................................... 32-37,49,68 

in river canyons, views of. ............................... 26,28 

in the Sierra Nevada ..................................... 27,67 

on beds of upland creeks, views of. ....................... 26, 27 

on inundated lands ...•................................... 49-50 

on piedmont slopes. See Piedmont depm;its. 

~om disused hydraulic mines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 

from drifting, volume of... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 

from hydraulic mining, dams for impounding. . . . . . . . . . . . . . . . 67 

estimates of total volume... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 

. influence on streams .. :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

investigations of.. .......................... · ......... ·.· ... 11,13 

surveys to measure quantity ............................. 38-40 

views of dam built to arrest .................... · ........... 52,60 

views of dams built to impound ............... .' .......... 66,67 

views of river valley flooded by ........................ 12, 26,52 

from mining and other sources, distribution in 1914 ........... 46-50 

from placer mining, volume of.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 

from quartz mining, ·volume of............................... 42 

from sources other than mining..... . . . . . . . . . . . . . . . . . . . . . . . 43-46, 64 

future movements and distribution of ........................ 64-68 

plain near Daguerre Point, view of.. . . . . . . . . . . . . . . . . . . . . . . . . . 52 

quality of, carried by rivers of the Sierra Nevada............. 58 

carried by Yuba River ................................... 52-58 

supplied to streams by agriculture ........................ 43,64 

supplied to streams by grazing............................ 44 

supplied to streams by roads and trails ...... , ............ 44, 64 

transportation by streams, laws of.. .......................... 13, 26 

views illustrating derivation from agriculture................. 44 

from overgrazing ...................................... 44, 45, 46 

from roads. • . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . 44 

from trails..... . . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . 44 

waves of; in Feather and Sacramento rivers.................. 30 

Delta marsh, view of, from San Joaquin River................... 74 

view of reclaimed ............................................. 19, 75 

Delta of Sacramento and San Joaquin rivers, described ........... 14,23 

deposition of debris on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4!i-50 

discussed with reference to question of subsidence............ 24 

Deltas of small creeks, small size of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

Demeritt, Capt. II. L., on mud and sand on Pinole ShoaL....... 94 

Deposit of debris in Herring Creek reservoir, view of. . . . . . . . . . ... . . 46 

Deposits of debris from hydraulic mines, classification of.......... 25 

from hydraulic mines in the piedmont belt. See Piedmont 

deposits. 

within the Sierra Nevada .......................... ~ ..... 46-47 

in bays, volume of, between dates of surveys.................. 32 

between 1849 and 1914..................................... 37 . 

in three bays, relative depths of.............................. 35 

on inundated lands of the Great Valley.. . . . . . . . . . . . . . . . . . . . . . 49-50 

Detritus from mining. See Debris. 

• Gate.................................................. 119 

estimate of. ................................................ 120-121 

Discharge of tidal slough, variation of, in relation to tidal period. 77, 

127-130 

variation of, in relation to water stage ...................... 13Q-133 

Discharges, sequence of, at entrance to bay........................ 80 

Distichlis.................................. ... . . . . . . . . . . . . . . . . . . . . 77 

Distribution of debris from mining and other sources ............. 46-50 

Dredge, gold-mining............................................. 63 

Dredging on Pinole Shoal ...................................... 94, 102 

Drifting, quantity of debris from ................ :................ 42 

Drowned topography about bays................................. 17 

Drowned valley, view of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

Drowned valleys of Montezuma Hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Dump of old placer mine, view of................................ 42 

Dumps from hydraulic mines, account of. •.................... 25, 27,67 

views of...................................................... 26 

Dune on Bradford Island, view of................................ 19 

Dunes east of Antioch ...........................................• 22, 24 

E. 

Earthquake of 1906, relation of, to stability of tide gages.......... 19 

and local subsidence of land. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Effective tidal prism, definition of................................ 72 

diagram illustrating ....................................... 71,72,85 

in long estuary...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 

of San Francisco Bay system ................................. 72-75 

Ellis, W. T., acknowledgments to................................ 7 

Encroachments on tidal prism, diagram illustrating... . . . . . . . . . . . 85 

Erosion and deposition, regulation of river-bed slope by ....... 26-27, 29 

Erosion of bed of Yuba River below dam, account of.. ..... ." ..•.. 58-60 

of bed of Yuba River below dam, maps sho\\ing............. 58 

· views showing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53,60 

of debris deposits, account of. ............................. ·21, 28,36 

views illustrating ..................................... 26, 27, 28 

of old hydraulic mine walls ................................... SQ-51 

of shell mound by waves, view showing... . . . . . . . . . . . . . . . . . . . 19 

of soil caused by beating of rain, view showing. . . . . . . . . . . . . . . 43 

by agriculture, account of ................ , ............... 43-44 

views showing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 

by overgrazing, account of. .............................. 44-45 

views showing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44,45, 46 

by roads and trails, account of............................ 44 

views showing. . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . 44 

of Yuba piedmont deposit ................................... 62,63 

See also Debris. 

Evolution Lake, view of sand bar in.. . . . . . .. .. .. .. .. . . . . . . . . . . . . 96 

F. 

Fault separating areas of unequal subsidence..................... 17 

.Feather River, debris deposit in, at Marysville................... 30 

early navigation of........................................... 15 

piedmont deposit of.......................................... 29 

slack water above mouth of Yuba River...................... 31 

volume of debris from mines in basin of...................... 41 

volume of debris in channel of, below Marysville............. 48 

volume of piedmont deposit of............................... 47 

Fields of plowed land suffering loss of soil, views of............... 44 

Fisheries, United States Bureau of. See Albatross surYey. 

Flocculation of suspended debris in bays ...................... 35, 49,91 

Flood basins cf Sacramento Valley, account of. ................... 14,65 

function as reservoirs.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15, 66 

map of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14,66 

Flood control in Sacramento Valley ........................... 12, 65-Q7 

Flood plane of Sacramento River, raising of, by mining debris ..•. 11,25 

raising of, by reclamation of inundated lands ................. 25,65 

by works for control of floods............................. 66 

Foote, A. D., cited on ancient inland sea......................... 23 

Fort Point, narrows opposite ................................ 71, 108,109 

plot of current observations near............................. 116 

position shown by map ..................................... 70, 109 

tidal s-tation ................................................. 73,117 

Four-fathom bank. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70, 71 

Franciscan Bight. . . . . . . . . . . . . . .. . .. . . .. . . . . . . . . .. . . . . . . . . .. . . . . . 96 

Frequency of high tides and low tides at different leYels ........ 135-136 
INDEX. 151 

G. Page. 

Gabring station, Smartsville ..•................................ 28, 55, 56 

Gaging stations for river discharge................................ 120 

Gilbert, A.M., current observations in Ravenswood Slough..... 124 

work or...................................................... 7 

Golden Gate, cond.ltion before sul)sidonce of land ................. 16,23 

lag or slack water at ........................................ 116-120 

Jnap of....................................................... 70 

ntap or narrows or. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 

moan volume or tidal currents ................................ 72-79 

moan volune or tropic ebb currents ........................... 79-82 

narrows of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 

ol)servations or tidul cmrents .............................. : 108-116 

tidnl currents at entrance.................................... 71 

tidal stations ....................................... 19-20,73,117,126 

velocities or tidal currents.................................... 89 

volume or tides in. See Tidal volume. 

Sec also Presidio cmd. Fort Point. 

Golden Gate bar, changes in form and height ............. 94-95, 139-148 

comparison or charts ....................................... 139-148 

cross profiles from soundings of 1873 and 1900................. 142 

depths or water on crest in 1873 and 1900 . . . . . . . . . . . . . . . . . . . . . 144 

interpretation of changes ................................ 95-100, 101 

Jnap.... .. ...... .... .... ...... .. . .. .. .. ... . .. .. ... .. . . . . . .. .. . 140 

Jnap or crest.................................................. 145 

natural processes of maintQnance ................... 69-71,96-97,101 

relations of debris movement to ............................. 69-103 

retreat of crest line ............................ 9.5, 98,99-100,101,145 

· size of sand grains on......................................... 91 

sources or constituent sand ......................... 69-71,91-94,101 

velocities of tidal currents on................................. 89 

volume of ebb tides on....................................... 84 

Golden Gate tidal stations, relation to earthquake................ 20 

Gold-mining dredge.............................................. 63 

Grazing in relation to soil waste.................................. 44 

Great Valley of California, deposits of debris on inundated lands. 49-50 

description of................................................ 14 

evidence on subsidence or.................................... 22 

. I. Page 

Inundated lands, account of..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

area.......................................................... 65 

deposits of debris on.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 

reclamation of. Sec Reclam11tion. 

Irrigation by water of Yuba River, project for .................. 106-107 

See also Agriculture. 

J. 

Johnson, W. D., photograph ofbar in Evolution Lake........... 96 

work of...................................................... 7 

K. 

Kitchen middens. Sec Shell mounds. 

L. 

Lag of slack water, defimtion ef. .......... :...................... 116 

in Golden Gate .. · ................................ 72-73,108,116-120 

in Ravenswood Slough ..................................... 136-137 

in slough entrances ......................................... 137-138 

Lands, inundated. Sec Inundated lands. 

Lawson, A. C., on subsidence of land............................. 16 

Leaves, views illustrating protection of so,;,l by................... 42 

Leidl, Charles, velocity observations in Golden Gate ........... • 109,114 

Levee built to protect Marysville from floods and mining debris, 

view of ............................................. . 

to reclaim a delta marsh, view of ........................... . 

See also Reclamation. 

Levees, natural, and lateral basins .............................. . 

of delta marshes ........................................ : . .. . 

Load, detrital, of streams ....................................... . 

Lobos, Point, drift of sand to .................. , .... : ............ . 

sand from beach ncar ....................................... . 

Louderback, George D., on analysis of sands .................... . 

Lunar epochs associated with current observations in Golden 

Gate ................................................ . 

M. 

Manship, George, .work of ....................................... . 

52 

75 

14,15 

23 

26 

69 

92 

92 

109 

Ground rmrowod by beating rain, view of. ...................... . 43 Manson, Marsdon, on ancient inland sea ........................ . 

7 

23 

65 

23 

41 

Grunsky, C. E., acknowledgments to ............................ . 7 on area of inundated lands .................................. . on ancient inland sea ........................................ . 23 on depth of peat in delta marshes ........................... . on area or inundated lands .................................. . 

on depth or peat in delta marsh ........................... ~ .. 65 on method of estimating hydraulic mining debris ........... . 23 on volume of d6bris in basin of American River ............•. 57 

47,48 

64 

65 

42 

51 

29 

on relation of run-off to precipitation ........................ . 

plan for control or Sacramento Valley floods ................. . 

Guadalupe Riv0r, change in mouth ............................. . 

H. 

65 

21 

Hall, William Ham., on annual volume of hydraulic mine tailings. 40 

on volume or d~bris deposits in Feather River................ 48 

on water stages of Sacramento River......................... 29 

report on mining detritus.................................... 11 

Hallett Point, projected dam at.................................. 106 

Hand bury, ~.aj. 'l'homas H., on ancwnt inland sea .... ,.......... 23 

member of Bonyamd commission . . . . . . .. . . .. .. .. .. . . . . . . . . . 11 

Harris, Dr. H.. A., acknowledgments to .......................... 7,108 

memorandum on rcducUon of soundings..................... 148 

on character of tides at San Francisco entrance.. . . . . . . . . . . . . . 120 

Harts, }.faj. \V. \V., on ancient inl11nd sell......................... 23 

on power of California Debris Commission.................... 12 

on volume of Yuba piedmont deposit....................... 47 

Haywards fault, map showing position . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

rclo.tion to twoas or su bsi(~once.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

Herring Crook rcset·voir, view of.. ........... :.................... 46 

Heuer, Maj. W. H., member of Bcnyaurd commission .. :........ 11 

on ancient inlo.nd sea......................................... 23 

Higgins, C. L., on volume of debris from hydraulic mines........ 42 

Hydraulic gold minos, views of. ................................. 12,29 

Hydraulic mining, development of............................... 11 

dumps of tailings from .................................... 25, 27,67 

views of. ..... · ........................................... 26,29 

influence on streams......................................... 25 

outlook for ................................................. 104-107. 

pits, surveys of............................................... ilft 

quantity of debris from ...................................... 38,43 

regulation of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

Sec also D6bris. 

Hydro-olectric power, project for development ....... ~ .......... . 106 

on volume of debris in basin of Yuba River ................. . 

plan for control of Sacramento Valley floods ................. . 

Manzanita leaves, view showing htter of ........................ . 

Manzanita mine, condition of pit after cessation of mining ....... . 

view of ..................................................... . 

Map of crest of Golden Gate bar in 1855, 1873, and 1900 .......... ·. 

of flood basins of Sacramento Valley ........................ . 

of Golden Gate and Golden Gate bar ........................ . 

145 

17 

70 

of Golden Gate bar........................................... 140 

of Golden Gate narrows...................................... 109 

of levee system for control of floods in Sacramento Valley.... 66 

of piedmont deposit of Yuba R1ver.. ... . . . . . . . . . . . . . . . . . . . . . . 52 

of Ravenswood Slough and marsh............................ 123 · 

of San Francisco Bay system and associated marshes......... 76 

showing co tidal lines of San Francisco Bay system. . . . . . . . . . . 72 

showmg distribution of data on subsidence................... 18 

showing chango in bed of Yuba River below dam............ 58 

showing changes in low-water channel of Yuba River........ 61 

Mare Island navy yard........................................... 101 

Mare Island Strait, bar at entrance of. ............ : ............ 101-103 

Marshes, tidal, in relation to subsidence of land ............... 17; 21, 23 

investigation of tidal prism ................................ 123-138 

map......................................................... 76 

natural encroachments on.................................... 21 

outward gro\vth.............. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

reduction of tidal volume by reclamation ......... 85-88, 101, 102, 103 

tidal storage on ............................. 75-79,81,83,84,123-138 

vegetation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 

Martin, G. C., on run-ofi of Sacramento drainage bo.sin ........... 50,89 

Marysville, early navigation to................................... 15 

lowering of Yuba River bed at............................... 28 

map showmg relation to Yuba piedmont deposit............. 52 

record of low-water stages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 

suspended matter in Yuba River............................ 56 

view of levee for protection of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 
152 INDEX. 

Page. 

Meadow, view of, illustrating erosion occasioned by overgrazing.. 45 

view of, illustrating protection of soil by grass................ 43 

Memorial of California Miners' Association. . . . . . . . . . . . . . . . . . . . . . . 12 

Mendell, Lieut. Col. George H., investigation of mining debris by. 11 

on changes in Golden Gate bar ............................. 139,140 

on conditions controlling depth of water on Golden Gate bar .. 94,95 

on volume of debris from hydraulic mines ................. _ .. 40,41 

on volume of debris in basin of Bear River._ ................. 47,48 

on water stages of Sacramento River ........ _______ . _ ..... _ . _ 29 

Mendenhall, W. C., work of. .................................... . 

Merriam, John C., investigation of shell mom1ds ... _ .......... _.. 18 

Meter, current, used in observations in Ravenswood Slough ... __ . 124 

Meter record impaired by vertical movements .. _.,._._ ......... __ 116 

Meters, current, used in obse~vations in Golden Gate........... 109, 110 

Mine tailings. See Dumps. 

Miners' Association, California, memoriill to the President of the 

United States ..... ________ ......... ___ ........ __ .... 12,105 

Mines, hydraulic, yield debris after cessation of mining ....... __ . 50 

hydraulic, views of..-------.------ __ ......................... 12,29 

old placer, views of..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 

Mining, hydraulic. See Hydraulic mining. 

placer. See Placer mining. . 

Page. 

Piedmont deposit of Yuba River, account of. ............. 28, 47,52-60 

map of. •....................................... _ . _ . _ . _ .. _ . . . . 52 

views of •................. _ ................... _ .. __ ._ .. __ .. 28, 52, 53 

views of dam built to restrain ................ _______ ... __ .... 52, 60 

Piedmont deposits, definition of. ...... _ ........... __ . ____ ........ 25 

estimates of volume ........... ___ .... _ .. __ ........ _ .......... 47-48 

future history ................................... _________ . . . . 67 

general history. __ . ____ .. ___ ......... _ ................. _ . _ . . . . 28 

Pine needles, view showing litter of ....... _____ .... ____ ......... 42 

Pinole Point, on line of Haywards fault.. __ . _ ... __ . __ ...........• 17 

position shown on map ............. __ ... _ ....... _. ___ .....•• 18 

Pinole Shoal, bed materiaL ...................... _ .. _ .... 91,92-94, 100 

loss of depth on, from depositton of sediment ....... _ ....... 101-103 

plans and works.to lower .•........ _ .. _____ .... ___ .. __ ... __ ... 102. 

relation to project for treatment of Yuba River .......... _.... 107 

velocity of ebb current ............................ _ ... __ ._ .... 81,89 

volume of tropic ebb current. ___ ................ _ ...... _ ..... 83-84 

Placer mining, early history . __ ...... ___ . __ ....... _ .. _. _......... 11 

quantity of debris from ... _ .................... _ .. _.......... 41 

sites of former, views of. ... _-.-· ... _ ........... __ ............• 42 

Plane of reference, changes in .............. ___ ... _ ... 87, 95,139,142,148 

nature and uses of. ............................. _ .... _ ........ 34, 75 

quartz, volume of debris from ...................... ---------· 

Mokelumne River delta marshes ............... ______ .... __ .... . 42 Plan for control of floods in Sacramento Valley ................ 12,65-67 

15 Plots of current observations in Golden Gate ............... __ .___ 116 

Montezuma Hills ................. __ ........... _. _. _ ............. 22,24 

Mountain View Slough, change in mouth~ ...... _................ 21 

Murphy, E. C., borings in river deposit at barrier No. 1......... 53 

on run-off of Sacramento drainage basin..................... 50,89 

work of...................................................... 7 

Mussel Rock ..•..•............................. :.................. 71 

N. 

Napa estuary, bar at entrance.................................... 102 

Napa Marsh, reclamation of. ..................................• 102,103 

tidal storage by ................................ 78, 79, 81, 83, 102-103 

Plots of current observations in Ravenswood Slough ........ _ . . . . 124 

Pond, H. S., workof............................................. 7 

Precipitation ratios compared with river discharges... . . . . . . . . . . . 121 

Precipitation records compared with run-off and movement of de· 

bris ............................. -.. ---- .... -- ....... . 57 

Presidio tidal data used with observations at Ravenswood Slough. 126 

Presidio tidal observations, annual means of ................ __ ... 19-20 

Presidio t1dal stages in relation to tidal storage on Ravenswood 

marsh ............................................. 133-136 

Presidio wharf tidal station ............. _._ .. __ .... __ .... _~...... 117 

Project for control of floods in Sacramento Valley. __ ........... 12, 65-67 Navigation, obstruction of, by bar at entrance to Mare Island 

Strait .•................. · ..... -. -. -.. -. --.. ---: -- ..... 102 Projects for resumption of hydraulic mining ...... __ ............ 105-107 

Protection against soil waste by grass, view illustrating. . . . . . . . . . 43 obstruction of, by mining debris in rivers ................ 25, 68, 104 

by Pinole Shoal. .... _ ..... _ ..........................•. 101, 102 

of Sacramento and Feather rivers............................ 15 

versus agriculture .......................................... 104-105 

versus hydraulic mining. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 

See also Golden Gate. 

Nelson, C. L., map of bed of Yuba River ........................ . 58 

by leaves, views illustrating.................................. 42 

Q. 

Q.uartz mining, volume of debris from ........ _. __ .. _ ........... . 42 

R. 

survey of bed of Yuba River •................................. 53 · Rain attack on bare ground, view illustrating .. _ .. _ .. ______ ._._ .. 43 

work of. •....••.•••.......................................... 7 Raised beaches ................................... _____ . _ . ___ . _ .. 16 

Nelson, N. C., archeologic studies about Suisun Bay ............ . 22 Range of tide. See Tidal range. 

on dissected terrace .......... _ .............................. . 17 Ravenswood marsh, area of. ....... __ ._ .. _ .. _.................... 123 

on shell mounds ............................................ . 

work of. ...................................... -----.--- .•. ---

19 

7 

Nevada City, view of field near................................... 44 

Newberry, J. S., on raised beach of San Pablo Bay............... 16 

Newark Slough, change in mouth................................ 21 

Non-lnining contribution to debris in rivers ................... 43, 46,64 

North Bloomfield mine, condition after cessation of mining . . . . . . 51 

viewsin.................. .... .. .. ....... .. .. .. .. . . .. . .. . .. .. . 29 

0. 

Observations of currents and water stages in Ravenswood 

Slough .................. _... . . . . . . . . . . . . . . . . . . . . . . . . 124-125 

of currents in Golden Gate ................................ 108-116 

Ocean Beach, movement of sand along........................... 69 

sand from. . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 

Ocean, Pacific, receives fine debris ............................... 48-49 

Outlook for hydraulic mining ................................. 104-107 

Overgrazing, views showing soil waste caused by .............. 44, 45,46 

Overmarsh tides, average water storage from ......... :........... 136 

definition of ................. _................................ 128 

discharge of, in relation to tidal period ................. 128,129,131 

P. 

Pacific Ocean ..... __ ............••.............................•. 48-49 

Parks Bar Bridge, piedmonfdeposit near ......... _ ......... ~..... 28 

views near .. ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 

Payson, Lieut. A. H., on volume of debris from hydraulic mines. . 42 

Penn Valley, view of............................................. 13 

Petaluma Marsh, shell mound on ......... : . ...................... , 19 

Piedmont deposit near its head, views of ....................... 12, 26, 28 

curves showing tidal storage in relation to rise and fall of tide. 130 

map of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 

subsidence of. .................... __ . ___ ...... _.............. 22 

Ravenswood Slough, changes at mouth ..... _ ................... 21, 123 

communication with Redwood Slough ............. _......... 123 

cross section at observation station .................. ____ .. _ . _ 124 

observations and studies of tidal discharge ........ __ ._ .. 75,123-128 

variation of discharge during a tidal period ................. 127-130 

Reclamation of inundated lands, influence on flood plane .. . . . . . . 25 

of inundated lands, stimulated by works for flood controL . . . 65 

of Napa tidal marshes ............................. _ ........ 102,103 

of tidal marshes, influence on tidal discharge ....... _ .. __ . _ 85-88, 101 

Reclamation Service, relation to investigation of mining debris... 13 

Rees, Lieut. Col. Thomas H., acknowledgments to............... 108 

Reservoir on Herring Creek containing debris from overgrazing; 

view of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 

Reservoir, suggested, on Yuba River .............. _ ........... 106-107 

Rice, R. C., investigation of effect of vertical motion on readings 

of current meter ............. _ ........... _ . . . . . . . . . . . 116 

observations of current velocity in Golden Gate ............ 109-115 

in Ravenswood slough ............. _..................... 124 

work of ........................ _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Rhodes, Capt. Harry W., acknowledgments to .... __ .. _. . . . . . . . . . 108 

Richardson Bay, view of......................................... 18 

River discharge, diagram to illustrate combination with ebb and 

flood discharges...................................... 119 

Rivers, laws of debris transportation by ........... _ .. _ ........... 26-27 

Rivers of the Great Valley, changes from artificial causes ......... · 29-31 

· natural condition ............... _ ............... _ . . . . . . . . . . . . 14 

plan for control of floods ............ _ . . . . . . . . . . . . . . . . . . . . . 12, 65-66 
' INDEX. 153 

Page. 

Rivers of tho Sierra Nevada, changes from artificial causes ........ 25-29 

natural conditwn............................................ 15 

River valley flooded by mining debris, view of................... 12 

Roads contributing debris to streams, views of................... 44 

Uonds In Yuba Ulvor basin, estimate of debris output of......... 44 

Uoso, A. B., cited on water stages of Sacramento River.......... 29 

Rushes .......................................... · ...... .'......... 77 

s. 

Sacramento basin, natural condltion or. .......................... 14-15 

Sacramento River, basins bordering ....•........................ 14,15 

changes from artificio.l causes................................. 25 

debris waves in bed.......................................... 30 

early navigation of .......................................... . 

form or continuation to ocean ................................ . 

15 

23 

Page. 

Sierra Nevada, natural condition of streams ...................... 15-29 

views illustrating topographic types.......................... 13 

Slack water in Sacramento and Feather rivers.................... 31 

Slack-water intervals at Golden Gate ................. 71-72, 108, 116-120 

in Ravenswood Slough ..................................... 136-138 

Slack water, tidal, definition of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 

times of, in Ravenswood Slough............................. 126 

Slope of ocean bed in Franciscan Bight........................... 96 

Slope of stream bed, conditions determining.. . . . . . . . . . . . . . . . . . . • 27 

Slough, Ravenswood. See Ravenswood Slough. 

Sloughs, changes in ............................................. 21, 123 

communicating ..................................... 79, 103, 123, 132 

Smartsville gaging station, records of discharge................... 55 

records of low water.......................................... 28 

records of suspended matter.................................. 56 

view of Yuba narrows........................................ 28 29 Smartsville, view of eroded hillside near.......................... 46 

slnck wntor nbovo mouth of Feather River................... 31 Soil protection, views illustrating ................................ 42,43 

low-water records at Sacramento ............................ . 

tldos · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 15• 

25• 73 Soil waste from agriculture, roads, and overgrazing •............. 43-46 

Sncramonto-San Joaquin delta, do posits of debris on· · · · · · · · · · · • · · 50 Soil waste, protection against, by grass, views illustrating....... 43 

features of.·················································· l4, 23 protection against, by leaves, views illustrating................. 42 

Sacramento-Sun Joaquin Valley, description of................... 14 viewsillustrating ....................................... 43,44,45,46 

clmngos in streams from artificial causes ...................... 25-31 Sorting of debris in river beds .................................... 31, 61 

Sacramento Valley, map of flood basins......................... 14 s din · th b 32 33 34 

map of projected levees for control of floods ............... :... 66 otm gs m e ays · · · · · · · · · · · · · · · · · · · · · · · · · ·: · · · · · · · · · · · · · ' '· Sotmdings, methods of reducing ....... :.......................... 148 

plan for control of floods·································· 12,65-67 minimum records of, selected for charts ..................... 34,143 

SallcorniC£. • · • • • • • • · • · • · • • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 77 samples of sand derived from................................. 92 

Samphiro. · ··· · · ·· · · ·· · · ·· ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 77 Soundings on Golden Gate bar, lines of ......................... 141,145 

So.nd bo.r in Evolution 1:-ake...... .. .. . . . . . . . . . . .. . . . . . . . . . . . . . . . 96 precision of. ....................................... 100,140,146,147 

Sand gro.lns, size of, compo.red with velocities of tidal currents .... 90-91 South Channel, currents of....................................... 71 

So.nd hill on Bradford lslo.nd, view of~ . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 map......................................................... 70 

Sand tnovOJnont on coast ......................................... 69,71 Spartina ••.••..•...•......................................... :. . . 77 

on Golden Go.to bo.r · · · · · · · · · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 71 Station for discharge observations in Ravenswood Slough ...... 123-124 

So.nd of Golden Go.to bar, sources of.··················· 69-71,91-94,101 Station, gaging, on Yuba River. See Smartsville station. 

wearing out of.······································· 91,97-98, 101 Stations for current observations in Gold on Gate, account of...... 108 

San Fro.ncisco Bay, amount of shoaling lJetween dates of surveys. 33 map showing................................................ 109 ctuvos of tropic tides and associated currents................. 80 Stations, gaging.................................................. 120 

datos of surveys.............................................. 32 tidal. ................................................. 19-20, 73, 117 

ovldonco of subsidonce about.································ 16- 21 Stone, C. H., suspended matter in Yuba River at Marys,Tille...... 56 

tnap · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 18• 72• 76 Subsidence of the land ........................................... 16-24 

vi ow of arm·········"·············· .. ······· .. ··············· 18 Subsidence, map showing distribution of data on................. 18 

view of shell mound on Brooks Island........................ 19 view of shell mound, illustrating............................. 19 

volume or debris deposits.................................... 37 view of sand hill, illustrating................................. 19 

San Fro.ncisco Bay system, average tidal storage on marshes .... 75-79 views illustrating relations of marshes to.. . . . . . . . . . . . . . . . . . . . 18 

cotidallinos. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 72 Suisun Bay, amount of shoaling between dates of surveys........ 32 

map·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 18• 

72• 76 dates of surveys.............................................. 32 

moan tidal volume··········································· 79 elevation and subsidence of land o.bout....................... 16 

moan tropic ebb tidal volume ................................ 79-82 estimates of debris deposits .................................. 32,37 

open-water moan effective tidal prism ....................... 72-75 sand from.................................................... 92 

See also San Pablo Bay, Suisun Bay, and Carquinez Strait. Suistm marshes, tidal storage on ........................... 78,81, 83,84 

San Francisco entrance. See Golden Gate and Golden Gate bar. Suisun marsh, view of........................................... 7fi 

San Fmncisco Harbor, .comparison of surveys at entrance ..... 139-148 Suisun, the...................................................... 108 

San Joaquin River, brackish water in mouth.................... 91 Surveys of bays, dates of......................................... 32 

view of delta marsh·········································· 74 of excavations by hydraulic mining.......................... 39 

volume of mining debris in basin of. . . . . . . . . . . . . . . . . . . . . . . . . . 42 of Golden Gate bar, comparison of ........................ ·. 139-148 

San 1\{ateo Slough, change in mouth· · · · · · · · · · · · · · · · · · · · · · · · · · · · · 21 Sutter Basin, below low-water level of Sacramento River......... 24 

San Pablo 13ay, amount of shoaling between dates of surveys.... 33 See also Flood basins. 

datos or surveys.............................................. 32 

flocculation of suspended mud in ......................... 35, 49,91 

marino terraces near. . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . 16 

subsidence ofland about..................................... 16 

volume of debris do posits in.................................. 37 

San Pablo Channel. See J>inole Shoal. 

San Pablo Narrows, bod material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

velocity of ebb current....................................... 89 

volume of tropic ebb current ................................ 83-84 

San Pedro Point ................................................. 69, 71 

So.usalito tidal station............................................ 19 

Schmitt, Vv. IJ., acknowledgments to ........................... . 

Scirpus.. .•. ........ ••.•.. ... .. . . ... . . . . . . .. . . . . . . . . . . . . . .. . . . . . . 77 

Scour by Yuba River at barrier No. 1 ........................... 58-60 

See also l~roslon. 

Sweetland, view of hydraulic mine near ......................... . 29 

T. 

Tailings from hydraulic mines, dams to impound ................ . 67 

views of dams to impound ................................... 66, 67 

See also Dumps. 

Taylor, Arthur, current observations in Golden Gate ....... 109,110-113 

current observations in Ravenswood Slough.................. 124 

Terraces formed by erosiOn of debris deposits, views showing .. 26, 27,28 

Terraces near San Pablo and Suisun bays........................ 16 

Tidal data at Ravenswood Slough and Presidio wharf............ 126 

Tidal discharge, curve showing relation to river discharge........ 119 

variation of,in Ravenswood Slough,in relation to tidal period. 127-130 

Tidal marshes, views of. ......................................... 74,75 

Sea-level determinations at Golden Gate ........................ . 19 views of reclaimed ........................................... 19, 75 

Sedge •........................................................... 

Shand, W. G., acknowledgments to ............................. . 

Sholl mound on l3rooks Island, view of .......................... . 

Shell mounds about Suisun Bay ................................ . 

standing below tide level .................................... . 

77 Tidal means, annual, at Golden Gate, m relation to subsidence of 

7 land. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-20 

19 Tidal period for currents, definition of............................ 127 

22 Tidal prism, definition of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

18 of tidal marshes ............................................ 123-138 
154 INDEX. 

Page. 

Tidal prism, relation to Golden Gate bar ...•.................... 97,101 

See also Effective tidal prism: 

Tidal range, effective, along main channel from Golden Gate to 

Sacramento.......................................... 74 

effective, definition of......................................... 72 

for current at Golden Gate ............................ 73,75,81 

for currents at other points ................ :.............. 83 

mean, at stations in San Francisco Bay system. . . . . . . . . . . . . . . 73 

Tidal slough, cnrves showing progressive variation of discharge in. 77, 128 

in Suisun marsh, view of..................................... 75 

Tidal stations at Golden Gate ............................. 19-20,7:1,117 

Tidal stations in San Francisco Bay system. . . . . . . . . . . . . . . . . . . . . . 73 

Tidal storage on marshes ........................ 7.'>-79, 81, 83, 84,123-1:18 

average amounts of, for tides of different classes .......... 75-76,136 

curves showing relation to rise and fall of tide .............. 130, 134 

mode of computing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78, 135 

relation to local rise and fall of tide ......................... 13Q-133 

relation to tides at Presidio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133-135 

Tidal volume, check computations of. ....................... 82,121-122 

in relation to size and position of Golden Gate bar ...... 7o-71, 96-97 

in relation to transportation of debris ........................ 79-80 

in Ravenswood Slough ..................................... 12.'>-127 

mean, at Golden Gate ..................... · ................... 72-79 

reduction by encro.achments on tidal prism. . . . . . . . . . . . . . 8.')-88, 101 

tropic, at Golden Gate ....................... :. . . . . . . . . . . . . . . 79-82 

at San Pablo narrows, Pinole Shoal, and Carquinez Strait. 83-84 

Tide, high, map showing progress through San Francisco Bay 

system............................................... 72 

Tides, channel, definition of...................................... 128 

diurnal inequality ...................................... 16, 118, 119 

in Sacramento River, relat10n to debris deposits.............. 29 

tabulated constants .......... : . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 

overmarsh, definition of...................................... 128 

tropic, relation to declination· of moon........................ 80 

sequence in San Francisco entrance...................... 80 

Topographic types of western part of Sierra Nevada, views illus· 

trating .............................................. . 13 

Trails contributing debris to streams, views of. .................. . 44 

Page. 

United States Hydrographic Office, acknowledgments to......... 95 

United States Lighthouse Service, acknowledgments to .......... 7, 108 

United States Reclamation Service............................... 13 

United States Weather Bureau, annual means of air pressure at 

San Francisco ....................................... . 

records of precipitation ............................... : ..... .. 

records of river stages at Sacramento ........................ . 

·university of California, acknowledgments to ................... . 

biological survey of bays .................................... . 

See also Albatross. 

20 

36 

29 

7 

92 

Upland creek valleys, views of debris deposits in ................. 26, 27 

Upland topography of western Sierra Nevada, view illustrating.. 13 

Uren, E. C., on volume of debris in basin of Bear River.......... 47 

v. Valley lands, debris deposits ..................................... 49-50 

Velocities of currents in Golden Gate ........................... 10S-116 

of currents in Ravenswood Slough ......................... 124-125 

of ebb currents stronger than flood velccities ............. so-81, 100 

Velocity observations in Golden Gate, plots of................... 116 

in Ravenswood Slough, plots of.............................. 120 

w. 

Waggoner, W. W., acknowledgments to.......................... 7 

reports as debris commissioner. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

Waste of soil from agriculture, roads, and overgracing ............ 43-45 

views illustrating .......................................... 43, 44,45 

Water power, project for cooperative stream control... . . . . . . . . . . . 106 

Water-stage observations in Ravenswood Slough, plots of........ 124 

Waves, comminution of sand by .......................... 91,97-98,101 

movement of sand by ........................................ 69,97 • 

of debris in Feather and Sacramento rivers................... 30 

Westdahl, Capt. L. H., acknowledgments to..................... 108 

West Point Slough............................................... 123 

Wilkins, J. T., on changes in depth of water on Golden Gate 

bar... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95, 99, 139 

Y. 

Trails in Yuba River basin, estimate of debris output of......... 44 Yolo Basin, below low-water level of Sacramento River .... : ..... 

Training walls at Daguerre Point, Yuba River ................... 62-63 See also Flood basins. 24 

map showmg. · · · ··· ......................................... 52 Yuba River, barrier No.!. ..................... · ............... 52-54,59 

TransportatiOn of debris by streams, laws of ..................... 26-27 canyon of, containing remnant of debris deposit, view of..... 26 

Trask, J. B., on raised beach of San Pablo Bay................... 16 in natural condition, view of. ............................ 13,20 

Tule. · ·· ·· ······ ·· ·· ·· · ······· ·· · · · · .. ·· ·· ·· ·· .... · · · ·· · · ·· · ·· ·· · 77 Daguerre Point dam and training walls ................... 61-63,64 

Turner, F. C., on volume of debris in Bear and American river detritalload of. ...... : ....................................... 52-58 

basins .. ·············································· 47 discharge record for floods of 1905-6........................... 55 

on volume of debris in Yuba River basin.................... 46 map oflow-water channels................................... 61 

on volume of hydraulic mining debris ........................ 39, 40 measurement of debris arrested by barrier No. 1.............. 53 

Typha.······························ .. ···· .... · .. · .. ···:········· 77 measurement of debris carried in suspension.................. 56 

u.· 

United States Bureau of Fisheries biological survey of bays. See 

Albatross. 

United States Coast and Geodetic Survey, acknowledgments to .. 7,108 

Coast Pilot ................................................ 40, 69, 71 

computations of annual mean-tide level at the Presidio....... 19 

currents at Golden Gate...................................... 71 

hydrographic sheets ........................................ 109, 140 

map· of Golden Gate.......................................... 71 

map of Golden Gate bar...................................... 140 

map of Golden Gate narrows................................. 109 

map of Ravenswood Slough.................................. 123 

methods of reducing soundings.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 

samples of sand.............................................. 92 

surveys of bays............................................... 32 

surveys of Golden Gate bar ... .' .............................. 94,139 

Tide Tables ....................... : ................... 72, 78, 133, 135 

0 

piedmont deposit of, future history of. ....................... 64-65 

history of. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 28 

n1ap of................................................... 28 

maps showing changes caused by dam.................... 58 

view of levee to restrain ......... :. . . . . . . . . . . . . . . . . . . . . . . . 52 

views of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28, 52, 53 

views of dam to restrain .................................. 52,60 

volume of... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 

profiles at barrier No. 1....................................... 59 

project for cooperative control. ............................. 106-107 

remodeling of channel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60-61 

scouring below barrier No. 1... . . . . .. .. . . . . . . . . . . . .. . . . . . . . . . . 58-60 

seepage at barrier No. 1. . . . . . .. . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . 60 

slopes of bed .......................................... 53, 59, 62, 106 

studies on .................................................... 52-60 

view of narrows ......... : ..... ~. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 

volume of debris lodged in upper basin....................... 46 

volume of mining debris from basin .......................... 38, 43