GEOLOGICAL SURVEY CIRCULAR 605 

Gold Distribution on 

the Sea Floor off 

the Klamath Mountains 

California 

Gold Distribution on 

the Sea Floor off 

the Klamath Mountains 

California 

By George W. Moore and Eli A. Silver 

GEOLOGICAL SURVEY CIRCULAR 605 

Washington 196 8 
United States Department of the Interior 

WALTER J. HICKEL, Secretary 

Geological Survey 

William T. Pecora, Director 

First printing 1968 

Second printing 1970 

Free on application to the U.S. Geological Survey, Washington, D.C. 20242 
CONTENTS 

Abstract---------------------------------------------------------

Introduction------------------------------------------------------

Field and laboratory methods--------------------------------------

Gold distribution -------------------------------------------------

Origin of the anomalously high gold values --------------------------

Conclusions------------------------------------------------------

References cited-------------------------------------------------

ILLUSTRATIONS 

Figure 1. Index map showing location of the project area and the 

Klamath Mountains gold districts------------------------

2-4. Map showing2. Location and gold content of the samples -------------

3. Weight percent of minerals heavier than 

methylene iodide in the samples--------------------

4. Relationship between gold anomalies and 

bedrock geology----------------------------------

TABLE 

Table 1. Location, depth, and analyses of samples-------------------

III 

Page 

1 

1 

2 

2 

3 

5 

5 

Page 

1 

3 

4 

5 

Page 

6 

Gold Distribution on the Sea Floor off the 

Klamath Mountains, California 

By George W. Moore and Eli A. Silver 

ABSTRACT 

Analyses of 82 samples collected from the surface of the continental shelf between the 0 reg o n-C a 1 i for n i a border and 

Eureka, Calif., indicate that the background gold content on this 

shelf is about 0.1 ppb (part per billion). Four anomalous 

tracts, which range in extent from 10 to 30 square kilometers, 

have gold values above l 0 ppb, and the richest sample contains 

390 ppb. The anomalous areas seem to lack a close cor r e 1 at ion 

with water depth, but they are related to areas underlain by soft 

C en o z o i c strata that contain small q u anti ties of dispersed 

gold originally derived from lodes in the Klamath Mountains. 

This relationship suggests that the offshore gold accumulations 

are lag con c en t rate s produced from the Cenozoic de p o s i t s 

by wave erosion during the postglacial rise in sea level. Gold 

contents at the surface are too low for economic recovery, and 

drilling will be required to de t e r m in e whether the anomalous 

areas are underlain by higher grade material. 

INTRODUCTION 

As part of the U.S. Geological Survey's Heavy Metals 

program, resource appraisals have been undertaken on 

areas of the continental shelf that lie offshore from 

mining districts on land that in the past have produced 

significant quantities of metals, such as gold and platinum. The shelf off northernmost California adjacent 

to the gold districts of the Klamath Mountains is one 

such area selected for study (fig. 1). To perform the 

investigation, a joint research contract was entered 

into with Scripps Institution ofOceanography. This report summarizes the results of the first year's work. 

The initial phase of the investigation has provided a 

fair understanding of the areal distribution of gold in 

the surface layer of sediment for a distance of about 

ISO kilometers along the northern California continental shelf. The sample spacing is close enough to define 

approximately shapes of areas with high gold values 

and to permit consideration of the significance of their 

relationship to other aspects of the geology. 

A companion pro j e c t dealing with the continental 

shelf off southern Oregon, directly north of this project 

area, is in progress through a joint research contract 

with Oregon State University. Preliminary reports 

have recently been issued on the first findings of that 

study (Clifton, 1968; Kulm and others, 1968). 

Sampling was done from Scripps Ins tit uti on of 

Oceanography's research vessel Oconostota in August 

and September 1967, and we are indebted to the 

officers, crew, and graduate students aboard the ship, 

who made the project a success. After the cruise, Norman Schumacher, of Scripps Institution of Oceanography, prepared the s amp 1 e s for chemical analysis 

and was responsible for determining the physical properties of the sediment. 

--.. l .,_.,-----.. 

-----~ ) 

I 

100 

OREGON 

100 STATUTE MILES I I 

200 KILOMETERS 

l 

I 

i 

\ 

Figure 1.--Index map showing l~cation of the 

project area and the Klamath Mountains gold 

districts. 
FIELD AND LABORATORY METHODS 

Most of the 82 samples considered in this report 

were taken with a sediment dredge developed by Andr~ 

M. Rosfelder, of Scripps Institution of Oceanography. 

Material enters the dredge through a cone-shaped 

scoop, from which it passes into a watertight bag that 

holds about 15 kilograms of sediment. The dredge was 

particularly effective on the homogeneous and firmly 

compacted sand of the shelf, which commonly resists 

penetration by samplers of the snapper type. During 

dredging operations, the device remained on the bottom 

for about 1 minute, while the ship drifted at 1-3 kilometers per hour. Sample locations are based on radar 

ranges and bearings to headlands, recorded at the time 

the dredge touched the bottom. 

The median diameter of the grains in the offshore 

samples ranges from 0.06 to 0.15 mm (millimeter). 

Inasmuch as a single grain of gold of these grain sizes 

is detectable by chemical analysis, a fairly large fraction from an original sample is required for an analysis to be representative, and the coarsest samples 

require the largest fractions. For each sample, we 

endeavored to select a weight for analysis according 

to grain size such that if the sample were to contain 

10 ppb (parts per billion) gold, the number of gold 

grains theoretically expected would be 1. 8, a value that 

provides an optimum 72.6 percent chance that the fraction will contain between 1 and 3 grains of gold (Dixon 

and Massey, 1957, table A-15) and hence will give an 

analysis between 5 and 15 ppb. The calculations, which 

assume that the gold grains are the size of the median 

diameter of the whole sample, were based on the relation 

where 

!! = weight in grams, 

.!? = the median diameter in centimeters, 

p =- the density of native gold in grams per cubic 

centimer, 

a = the grade in parts per billion, and 

A = the expected number of gold grains. 

When p = 17 gjcm3, o = 10 ppb, A = 1.8, and Dis replaced by ~ in millimeters, this relation reduces to 

n • 1.6·106 d3. - - A's an example, 2100- g fractions were used for samples 

with a median diameter of 0. 11 mm. The precision of 

analysis would be greater for d sample with a gold 

content higher than 10 ppb, or with a median diameter 

for gold grains smaller than that of its o~her grains,. 

as in these cases the analyzed fraction would contain 

more than the 1-3 grains of gold c a 11 e d for in the 

equation. 

The chemical an a 1 y s e s were made by atomicabsorption spectrophotometry according to the method 

developed by VanSickle and Lakin ( 1968). The digestion 

2 

and e~traction procedures used in this method require 

that the sample not exceed a weight of 100 g; hence, 

the heavy minerals in the fractions were first concentrated to less than 100 g by separation with heavy 

liquids. Bromoform, with a specific gravity of 2.85, 

was used in a first stage of separation, followed by 

methylene iodide, with a specific gravity of 3. 3. Fractions from sand samples were separated in 100-g 

batches in steep-walled glass funnels 15 centimeters 

in diameter; two silt samples were separated in 40-g 

batches in a centrifuge. 

Gold values for 61 of the samples studied are given 

in table 1 and contoured in figure 2. The v a 1 u e s reported are the calculated gold content of the samples 

before concentration. Gold analyses were not obtained 

for the 21 remaining samples, but comparison offigure 

2 with figure 3, which is a plot of the percent of each 

sample that is heavier than methylene iodide, shows 

that in areas for w h i c h both percent h e a v i e r than 

methylene iodide and gold analyses are available, the 

two show a fairly close correlation. Therefore, the 

methylene iodide percentages can be used to estimate 

the probable gold content. 

GOLD DISTRIBUTION 

Surface sediment in four are as on the no.rthernmost California continental shelf contain gold values 

greater than 10 ppb.l/ These areas are north of Point 

St. George, west of Crescent City, south of the mouth 

of the Klamath River, and north ofTrinidadHead. The 

highest value obtained in this investigation, 390 ppb, 

was in a sample from the area north of Trinidad Head. 

Background gold content is about 0.1 ppb. No clear-cut 

relationship appears to exist between water depth and 

gold content. The four samples that define the gold 

anomaly north of Trinidad Head were all collected at 

depths ranging from 20 to 22m (meters), but no other 

samples collected at other depths in this area were 

analyzed. The anomalous samples south of the Klamath River came from depths ranging from 16 to 27m, 

those north of Point St. George, from depths of 18 to 

29m, and the samplewestofCrescentCity, from 42 m 

depth. Samples with only background gold values occur 

at similar depths near each of these anomalously rich 

areas. 

The absolute ratio between gold and other heavy minerals changes systematically toward the south. For 

samples of similar gold content, the percent heavier 

than methylene iodide decreases by a factor of about 

4 from the north end of the project area to the south 

end (table 1 ). Chromium content (table 1) similarly 

is much greater north than south of Point St. George, 

which lies at 41 o 4 7' N. The analyses also show a poor 

correlation between chromium and gold. The available 

evidence indicates mixing of a chromium-bearing 

!/ Based on a price of$35 per ounce for gold, 10 ppb 

is equivalent to 1 cent per ton, or 1.6 cents per cubic 

yard. 
• 

~ • 0 •• n 

t:r:1 

> z • 

• 

124 °20 1 10 1 

EXPLANATION 

,..--100--' 

Gold isopleth 

In parts per billion 

.,.,..--50---

Submarine contour 

From USC&GS chart 

1308N-12; contour 

interval 50 meters 

10' 

50' 

0 10 KILOMETERS 

II II I I I I I I I 

Figure 2.--Map showing location and gold content of the samples. 

heavy-mineral suite from the north with a gold-bearing heavy-mineral suite derived from the Klamath 

Mountains to the east. 

ORIGIN OF THE ANOMALOUSLY HIGH GOLD VA LUES 

The rather broad depth range within which the gold 

anomalies occur and their discontinuous nature along 

3 

the coast suggest to us that they do not occur on relict beaches, in the sense of being at stillstands of 

Pleistocene ·sea level. The gold anomalies do bear a 

relationship to the bedrock geology, however, and this 

may be genetically significant. The offshore geology of 

part of the project area has been reported on earlier 

(Moore and Silver, 1968), and mapping by acoustic-
.. :.'··-:\ 'IJl 

.. 

f: ~ c" ..• ~-C<:-

~:: ~ ,~ :: ~ ... . .'! .. George 

• 

• 0 • I 

Cl • 

t_:rj 

> •• z 

• 

EXPLANATION 

......--1~ 

.:Heavy-mineral isopleth 

·Percent heavier than 

3.3 g/cm3 

..--so____.. 

Submarine contour 

From USC&GS chart 

1308N-12; contour 

interval 50 meters 

10' 

50' 

10 KILOMETERS 

"''''"'" 

Figure 3.--Map showing weight percent of minerals heavier than methylene iodide in 

the samples. 

reflection profiling methods of the remainder of the 

area sampled for gold has now been completed. This 

mapping shows that a single common denominator relates all the areas of anomalously high gold content to 

the bedrock geology. Each such area overlies a northwest-trending syncline containing upper Cenozoic deposits that carry small quantities of dispersed gold, 

4 

originally derived from lodes in the Klamath Mountains (fig. 4). This relationship is true also of two minor anomalies at the ~outh end of the area near Eureka 

(fig. 2). 

To explain the gold anomalies, we offer the following 

hypothesis: During the Holocene rise of sea level that 
124°20' 10' 42° --r.-.,.-----w 00' 

EXPLANATION 

50' ~ 

Tertiary sedimentary rocks 

0' I KJm I 

Cretaceous and 

Jurassic metamorphic rocks 

Contact 

Cenozoic - fault 

' Area where surface 

sediment contains 

more than 10 parts 

per billion gold 

0 10 KILOMETERS 

I I 

Figure 4.--Map showing relationship between 

gold anomalies and bedrock geology. 

5 

followed the Wisconsin Glaciation, encroaching waves 

attacked and reworked the soft gold-bearing Cenozoic 

deposits. Other constituents of the deposits were transported away by the attacking waves, and the gold 

a c cum u 1 ate d offshore as a lag con c en t rat e. 

Acoustic-reflection profiles indicate that the postglacial deposits in the areas of the anomalies are as 

thick as 10 meters. 

CONCLUSIONS 

Surface sediment in localized areas on thenorthern 

California continental shelf contains gold that occurs 

as probable lag accumulations above synclinal bodies 

of soft upper Cenozoic material that was eroded by 

waves along the shore of the rising postglacial sea. 

Each of four anomalies in which the gold content exceeds 10 ppb covers an area of more than 10 sqw.are 

kilometers, and the richest individual sample contains 390 ppb gold. The gold content of the surface 

sediment is too low to be of economic significance, 

and drilling will be necessary to provide information 

on the distribution of gold at depth within the deposits 

and on the possible occurrence of minable gold resources below the anomalies. 

REFERENCES CITED 

Clifton, H. E., 1968, Gold distribution in surface sediments on the continental shelf off southern Oregon: 

A preliminary report: U.S. Geol. Survey Circ. 587, 

6 p. 

Dixon, W. J., andMassey, F. J., Jr., 1957, Introduction to statistical analysis, 2d ed.: New York, 

McGraw-Hill, Inc., 488 p. 

Kulm, L. D., Heinrichs, D. F., Buehrig, R. M., and 

Chambers, D. M., 1968~ Evidence for p o s sib 1 e 

placer accumulations on the southern Oregon continental shelf: Ore Bin, v. 30, p. 81-104. 

Moore, G. W., and Silver, E. A., 1968, Geology of the 

Klamath River delta, California: U.S. Geol. Survey 

Prof. Paper 600-C, p. C144-Cl48. 

VanSickle, G. H., and Lakin, H. W., 1968, An atomicabsorption method for the determination of gold in 

large samples of geologic materials: U.S. Geol. 

Survey Circ. 561, -! p. 
Table I.--Location, depth, and analyses of the samples 

[Altitude of beach samples above mean lower low water indicated by + in depth column; 

heavy-liquid separations by N. Schumacher; gold analyses by W. L. Campbell, T. G. Ging, 

R. F. Hansen, R. Leinz, M. S. Rickard, T. M. Stein, and z. c. Stephenson; chromium 

analyses by J. P. Cahill, C. Huffman, v. E. Shaw, and J. A. Thomas] 

Location Depth Median Heavier than Heavier than Gold Chromium 

(meters) diameter bromofom methylene iodide (parts per (percent) Lat N Long w (millimeters) (percent) (percent) billion) 

41°59.6' 124°16.3 1 27 0.11 12.7 1.5 0.1 0.080 

41°59.5 1 124°14.8 1 20 .12 5.6 .8 1.0 .070 

41°58.5' 124°14.6 1 18 •I 

.12 6.8 .8 .1 .068 

41°57.6 1 124°14.9 1 18 .12 15.0 2.1 -- .15 

41°57.5' 124°16.0 1 22 .12 21.1 4.6 -- .15 

41°56.6 1 124°14.7 1 18 .12 23.9 2.0 -- .24 

41°55.7 1 124°16.4 1 27 .11 33.0 7.2 -- .41 

41°55.5' 124°14.4 1 22 .11 25.0 4.4 .7 .31 

41°55.0' 124°21.9 1 59 .06 6.6 .8 -- --

41°54.3 1 124°14.4 1 18 .12 41.0 1.8 .7 .43 

41°53.6 1 124°16.0 1 27 .11 38.4 9.2 .4 .62 

41°53.4 1 124°14.7 1 18 .11 42.0 5.3 .1 .31 

41°52.3' 124°14.4 1 18 .11 30.5 7.4 1.6 .22 

41°52.1 1 124°12.8 1 +2 .43 16.4 1.7 .2 .047 

41°51.5 1 124°15.8 1 29 .11 34.7 11.5 13. .80 

41°51.4 1 124°14.6 1 18 .12 30.6 2.3 .2 .45· 

41°50.3' 124°16.3 1 29 .12 29.5 8.4 7.1 .68 

41°50.2' 124°15.0' 18 .12 37.8 12.8 4.0 .68 

41°49.4 1 124°15.3 1 18 .13 28.5 5.7 2.6 .57 

41°45.9 1 124°13.8 1 +1 1.06 24.2 2.9 -- --

6 
Table I.--Location, depth, and analyses of the samples--Continued 

Location Depth Median Heavier than Heavier than Gold 

diameter bromoform methylene iodide (parts per 

Chromium 

(meters) Lat N Long w (percent) (millimeters) (percent) (percent) billion) 

41°44.2' 124°15.8' 42 0.13 41.6 11.9 15. --

41°44.1' 124°10.7' 5 .14 13.1 .6 <.1 --

41°43.2' 124°14.6' 37 .12 16.9 1.9 -- --

41 °41.6' '124°10. 7' 18 -- 8.0 .1 <.1 --

41°38.6' 124°10.7' 32 -- 6.0 <.1 <.1 --

41°36.8' 124°10.8' 33 .08 2.4 .2 .6 .024 

41°36.2' 124°06.0' +1 -- 2.7 .1 . 3 --

41°35.8' 124°10.0' 33 .09 10.8 .4 .5 .049 

41°35.2' 124°12.4' 41 .09 12.9 .4 1.2 --

41°35.0' 124°10.0' 33 .08 2.6 .1 .3 .030 

41°34.2' 124°09.5' 31 .09 4.1 .8 -- .058 

41°33.5• 124°09.0' 31 .10 5.6 .2 -- .031 

41°33.1' 124°07.8' 20 .11 2.2 .2 .1 .030 

41°32.9' 124°09.0' 31 .12 11.6 .8 .7 .038 

41°32.8' 124°06.3' 18 .09 9.3 .9 .9 .060 

41°32.0' 124°06.3' 16 .11 13.4 1.6 5.3 .055 

41°31.9' 124°09.0' 27 .12 15.0 .8 .7 .046 

41 O 31.2 I 124°07.5' 18 .12 12.5 .9 .7 .047 

41°30.9' 124°08.6' 27 .12 11.0 .8 .5 .048 

41°30.4' 124°08.6' 29 .12 3.8 .4 .2 .030 

41°29.3' 124°07.2' 18 .12 9.6 .7 .8 .045 

41°28.6' 124°06.7' 18 -- 17.3 .2 <.1 --

41°28.5' 124°08.3' 18 .12 6.3 .7 1.2 .054 

41°27.6' 124°06.0' 16 .12 3.0 .8 .4 .038 

7 
Table I.--Location, depth, and analyses of the samples--Continued 

Location Depth Median Heavier than Heavier than Gold 

diameter bromoform methylene iodide (parts per 

Chromium 

Lat N Long w (meters) (millimeters) (percent) (percent) billion) (percent) 

41°26.0' 124°08.1' 27 0.12 i 12.0 1.4 55. 0.065 

41°25.7' 124°05.8' 17 -- 12.4 .4 <.1 --

41°25.7' 124°05.1' 16 .13 12.9 1.5 9.4 .040 

41°24.8' 124°09.0' 46 .09 6.2 .3 -- -- 41°24.6' 124°06.9' 24 .13 35.5 3.6 -- --

41°23.8' 124°08.0' 27 .13 17.1 1.6 22. .077 

41°23.4' 124°05.8' 16 -- -- .5 <.1 --

41°22.9' 124°05.5' 15 .13 6.7 1.0 <.1 .024 

41°21. 4' 124°06.7 15 .13 8.8 .4 <.1 .044 

41°21.4' 124°04.5' +3 .34 41.4 5.1 -- --

41°20.9' 124°09.0' 38 .12 9.4 1.4 -- .060 

41°20.7' 124°07.4' 18 .12 1.2 .1 -- .022 

41°19.6' 124°09.9' 42 .09 1.4 .7 -- .025 

41°18.7' 124°07.3' 22 .13 10.0 .7 1.2 .060 

41°17.4' 124°07.6' 22 .11 6.9 .5 <.1 .065 

41°15.2' 124°08.0' 22 .12 21.3 4.1 11. .20 

41°13.4' 124°08.3' 20 .13 4.6 • 5 13 • .044 

41°12.1' 124°09.2' 22 .13 19.3 1.7 -- --

41°12.0' 124°08.2' 15 .13 12.6 .6 -- --

41 O 11.4 I 124°09.0' 20 .13 14.4 1.1 390. .098 

41°10.1' 124°09.9' 20 .13 14.1 1.4 11. .10 

41°09.8' 124°13.1' 53 .06 1.9 .1 <.1 .018 

41°08.2' 124°12.6' 22 .13 2.3 .1 <.1 .015 

41°06.3' 124°12.5' 38 .13 4.6 .5 <.1 .041 

8 
Table I.--Location, depth, and analyses of the samples--Continued 

Location Median Heavier than Heavier than Gold 

Depth Chromium 

diameter bromoform methylene iodide (parts per 

Lat N I Long W (meters) (millimeters) (percent) (percent) billion) (percent) 

41°01.4' 124°09.1' 15 Q.l3 1.1 Q.l <0 .1 .10 

41°00.4' 124°08.8' 15 .13 .8 .2 .1 .015 

40°59.2' 124°08.8' 15 .13 1.2 .1 .1 .011 

40°57.9' 124°09.5' 22 .13 1.6 .1 -- .018 

40°56.3' 124°09.8' 27 .14 3.7 .4 -- .033 

40°54.9 ,; 124°10.6' 29 .14 7.4 .4 .5 .053 

40°53.2·' 124°10.6' 20 .15 7.6 .7 <.1 .060 

40°49.9 'I 124°12.3' 18 .15 13.6 3.8 8.1 .22 

40°44.4' 124°16.8' 27 .14 2.2 .2 <.1 .011 

40°41.9 I 124°18.4' 31 .10 .7 .1 <.1 .016 

40°41.4' 124°24.0' 60 .10 . 7 . 2 -- .018 

40°40.31. 124°21.7' 27 .12 1.5 .3 .3 .020 

I 

40°37.0' 124°20.9' 18 .13 2.0 .2 -- .037 

40°34.8' 124°22.4' 18 .13 2.4 .4 1.2 .042 

1< U~S. GOVERNMENT PRINTING Of'f'ICE: t970 0-381-007 

9