Bulletin No. 306 B' DescriPtive Geology, 109 

F, Geography, 54

DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, DIRECTOR

RATE OF OF NIAGARA FALLS

BY

G-. K. G-ILBERT

ACCOMPANIED BY A REPORT ON THE SURVEY OF THE CREST

W.

WASHINGTON .

GOVERNMENT PRINTING OFFICE

1907

CONTENTS.

Page.

Introduction...........................-.........................."........ 5

The Horseshoe Fall........................................................ 13

The American Fall ............... 7........................................ 17

The map of 1842......................................................... 23

Summary and conclusion................................................... 25

Keport of survey of crest line of Niagara Falls/ by W. Carvel Hall............... 26

ILLUSTRATIONS.

Page.

PLATE I. Horseshoe Fall, 1886............................................... 5

II. Map, crest lines of Niagara Falls in 1842, 1875, 1886, 1890, and 1905.... 10

III. Sketch of Horseshoe Fall, 1SZ7..................................... 15

IV. Photograph of Horseshoe Fall, 1895................................. 15

V. Sketch of American Fall from Goat Island, 1827. ..................... 17

VI. Photograph of American Fall from Goat Island, 1895.................. 17

VII. Sketch of American Fall from Prospect Point, 1827................... 19

VIII. Photograph of American Fall from Prospect Point, 1895 ............... 19

I.. American Fall, 1854 or 1855, from daguerreotype..................... 20

X. Eastern part of Horseshoe Fall, about 1885. .. .--...°................. 22

XI. American Fall, about 1885............. ........................... 22

FIG. 1. Diagrammatic profile of Horseshoe Fall............................. 5

2. Bird's-eye view of Niagara River................................... 6

3. Map of Niagara gorge......:...................................... 6

4. Outlines of Horseshoe Fall in 1842, 1875, and 1905................... 14

5. Sketch of American Fall, with lines used in transferring directions...... 20

6. Map of-Niagara Falls, with lines of direction......................... 20

7. Plan of American Fall............................................ 21

8. Profile and section of American Fall................................ 23

U. S. GED 1 ni.irAL SURVEY 

THE HORSESHOE.

Date of photograph, about 1 886. The head of the Horseshoe curve recedes more rapidly than any other par

developed after 1 827.
RATE OF RECESSION OF NIAGARA FALLS.

By G. K. GILBERT.

INTRODUCTION.

The erosive Work of the cataract of Niagara is exceptionally rapid. 

This depends primarily on the great power of the falling water, but 

in part on the character of the local geologic structure. The rocks 

are stratified and lie nearly level. The upper layers are of limestone, 

strong and resistant; the lower, consisting chiefly of shale, are comparatively weak and yielding. As the shales are worn away below 

the limestone beds are undermined, so that their edges project like 

a cornice and are deprived of support. From time to time they 

yield to the force of their own weight and fall away in large blocks. 

Each rock fall causes a jar of the __ 

ground which is perceived by 

people in the vicinity, and results 

in a modification of the crest of 

the cataract which is readily seen 

by anyone familiar with its outline. Such changes of the crest 

have been observed from time to 

time ever since the neighboring 

banks of the river were occupied 

by white men. It is highly probable that they were also observed 

by Indians before the advent of white men, but on this point I have 

made no inquiries, as Indian traditions are not likely to be sufficiently 

definite to aid in determining the rate of progressive change in the 

position of the cataract.

The surface of Lake Erie is 325 feet higher than the surface of 

Lake Ontario. The belt of land between them includes two plains, 

of which the higher and broader is raised but little above the level of 

Lake Erie, and the lower slopes gently to the shore of Late Ontario. 

The descent from the upper to the lower is abrupt, constituting a 

line of cliffs parallel to the shore of Ontario and known as the Niagara

5

FIG. 1. Diagrammatic profile of Horseshoe Fall, 

illustrating mode of erosion and recession.
6 BATE OF KECESSION OF NIAGAKA FALLS.

escarpment. The river; issuing from Lake Erie at Buffalo, flows at 

first on the upper plain. It is there broad and comparatively shallow and has no valley. At the falls it suddenly drops into the head 

of a narrow gorge which is 6 miles long and extends to the escarpment. Within the gorge it is narrow and contained by steep walls. 

Near the head of the gorge the water is deep, the current moderate, 

and the descent small, but farther on are fierce rapids with steep 

descent. Some of these relations are shown in fig. 2. As the falls

are at the head of the gorge, it 

is evident that their recession 

makes the gorge longer.

Among the early observers of 

the falls was McCauslin, who 

remained there % from 1774 to 

17.83. After describing the escarpment at Queenston he says: a

It is universally believed that the cataract was originally at this ridge, and that 

it has by degrees worn away and broke 

down the rock for the space of these six 

or seven miles. Some have supposed that 

from these appearances, conjectures might 

be formed of the age of this part of the 

world. To enter upon such a calculation, 

it would previously be necessary to ascertain how much the fall had retired in a 

hundred years, or any other certain period. 

Suppose that we were even in possession 

of such a fact, still ,the conclusions drawn 

from it would be liable to the greatest 

uncertainty, as it is evident that the space 

of rock broke down and worn away in a 

certain number of years would not always 

be the same. The more or less hardness 

and brittleness of the rock in different 

parts; the greater or less severity of the frosts in different years; and the quantities of 

water that flowed at different periods in the cataract of the river, would all occasion considerable variations. This retrocession of the Falls does not by any means go on so quickly 

as some have imagined. During nine years that I have remained at Niagara, very few 

pieces of the rock have fallen down which were large enough to make any sensible alteration in the brink; and in the space of two years I could not perceive, by a pretty accurate 

measurement, that the North-East brink had in the least receded. If we adopt the 

opinion of the Falls having retired six miles, and if we suppose the world to be 5,700 years 

old, this will give about sixty-six inches and an half for a year, or sixteen yards and two 

thirds for nine years, which I can venture to say has not been the case since 1774.

o McCauslin, Robert, An account of an earthy substance found near the Falls of Niagara and vulgarly 

called the spray of the falls, together with some remarks on the falls: Trans. Am. Philos. Soc., vol. 3, 

1793. (Read October 1C, 1789.) The passage cited is on pages 23-24.

FIG. 2. Bird's-eye view of Niagara River. The 

view is southward, or upstream, from a point 

above the shore of Lake Ontario, and shows the 

two plains, the escarpment, and the gorge. B, 

Buffalo. NF, Niagara Falls. L, Lewiston. Q, 

Q.ueenston. EE, Niagara escarpment.
INTRODUCTION.

Enys, who visited the cataract in 1787, quotes the opinion of 

residents that "the Falls have altered their 4 position or retreated 

since the memory of men," a but dissents from the view (which seems 

also to be generally entertained) that the original situation of the 

falls was at Queenston.

Weld, whose visit to the falls was in 1796, says that "even within 

the memory of many of the present inhabitants of the country, the 

falls have receded several yards." b 

He favors the theory that the gorge 

from. Lewiston to the falls was 

made by the falls, and his discussion of the subject shows him to 

have been a close observer and 

clear thinker.

Volney two years later repeats 

the general statement of observed 

recession, and adds: c

If the European colonists or travellers, to 

whom this region has been accessible for a 

century and a half, had made careful memorandums, from time to time, of the state of 

the fall, we should, by this time, have been 

able to trace the progress of those revolutions, which are easily proved to have taken 

place, by vestiges and indications which present themselves at every step.

And still further, in a footnote:^

It is extremely desirable that the government of the United States, at present under 

the direction of a friend to the arts and sciences [Jefferson], should order to be drawn up 

an exact description of the present state of the cataract. This statement, compared with 

subsequent appearances, observed from time to time, would enable us to trace with certainty the changes that may hereafter take place.

Francis Hall, 1816, says: 6

The name of "the Horse shoe," hitherto given to the larger Fall, is no longer applicable: 

it has become an acute angle. * * * An officer who had been stationed in the 

neighbourhood thirty years, pointed out to me the alteration which had taken place in the 

centre of the Fall, which he estimated at about eighteen feet in the thirty years.

FIG. 3. Map of the Niagara gorge, showing its 

relations to the falls and the escarpment.

a Kept. Canadian Archives, 1880 (published 1887), p. ccxxxii.

b Weld, Isaac, j r., Travels through the States of North America and the Provinces of Upper and Lower 

Canada during the years 1795,1796, and 1797, London, 3799, p. 320.

c Volney, C. P., A view of the soil and climate of the United States of America, etc., translated by 

C. B. Brown, Philadelphia, 1804, p. 92.

d Op. cit.

« Hall Lieut. Francis, Travels in Canada, and the United States, in 1810 and 1817, Boston; republished from the London edition by Wells & Lilly, 1818, p. 144.
8 RATE OF RECESSION OF NIAGARA FALLS.

Gilpin, whose visit was probably a few years later, says: a

The toe of the shoe, however, is now an angle, rather than a curve; but the inhabitants 

and early visitors affirm that it was formerly more round, and has gradually assumed its 

present angular form, within their recollection. * * * Mr. Forsyth, who has resided 

upon the spot for more than forty years, says, that within his recollection, the centre of 

this fall has receded from ten to fifteen yards; and, as some intelligent travellers have 

placed upright a few large stones in front of the hotel, which, when taken in a line, point 

exactly to that spot, it will of course be ascertained, at the end of a certain number of 

years, how much this centre recedes annually.

Schoolcraft, whose visit was in 1820, describes the undermining 

of the limestone by the fretting away of the shale, and mentions with 

approval the theory that the falls were anciently at Lewiston. He 

says: 6

* * * The wasting effects of the water, and the yielding nature of the rocks, remain 

the same, and manifest the slow process of a change, at the present period, as to position, 

height, form, division of column and other characters, which form the outlines of the great 

scene; and this change is probably sufficiently rapid in its operation, if minute observations were taken, to imprint a different character upon the Falls, at the close of every century. Nothing in the examination of the geological constitution, and mineral strata of 

our continent, conveys a more striking illustration of its remote antiquity, (still doubted 

by many) than a consideration of the time, it must have required for the waters of Niagara, 

to have worn their channel, for such an immense distance, through the rock. It is true, 

we are in possession of no certain data, for estimating the annual'rate of their progress, or 

for comparing the results with the Mosaic history of the earth. All that can be presumed 

is, that this progress, is now as rapid, as it was in former ages. * * *

Maps and descriptions are now extant, which will enable us to fix the rate of its progress, 

on the expiration of the present century, and we should not be disappointed in our anticipations, if its progress is found, greatly to exceed the prevalent expectation. To aid in 

the determination, the Island of Iris, which extends from the brink of the Fall, up the river, 

and which is now connected with the shore, by a wooden bridge, appears to present great 

facilities. A simple measurement of its length, with a monument for recording it at its 

head, would convert it into a graduated scale, and the point of the indentation of the 

Hurse Shoe Fall, could, in like manner, be perpetuated on either shore, by a series of corresponding ccleslJal observations, for determining the longitude of the extreme point of 

tnat incurvation. Distant ages would thus be furnished with data, the precision of which, 

would probably enable them to throw new and important lights on the history of the earth, 

and the changes it has undergone. Is this suggestion of too visionary a nature, to merit 

the consideration of geological societies?

Capt. Basil Hall, R. M., made a study of the cataract in 1827, 

and two years later published an excellent description, from which 

I quote: 6

In the course of our investigations and rambles, we met a gentleman who had- resided 

for the last thirty-six years in this neighborhood happy mortal! He told us that the 

Great Horse Shoe Fall had, within his memory, gone back forty or fifty yards that is to 

say, the edge, or arch of the rock over which the water poured, had broken down from time 

to time to that extent. This account was corroborated by that of another gentleman, 

who had been resident on the spot for forty years.

o Gilpin, H. D., A northern tour; being a guide to Saratoga, Lake George, Niagara, Canada, Boston, etc., Philadelphia, 1825, p. 149.

6 Schoolcraft. Uenry R., Narrative journal of travels, etc., made in 1820, Albany, 1821, pp. 45-47.

cHall, Capt. Basil, Travels in North America in the years 1827 and 1828, vol. 1, Edinburgh, 1829, pp. 

195-197.
INTRODUCTION. 9

As these statements came from persons of good authority, 1 was led to examine the geological circumstances more minutely; for I could not conceive it possible, that the mere 

wearing of the water could perform such rapid changes upon hard lime-stone. The explanation is very simple, however, when the nature of the different strata is attended to. In the 

first place, they are laid exactly horizontal, the top stratum being'a compact calcareous 

rock. In the next place, I observed, that in proportion as the examination is carried downwards, .the strata are found to be less and less indurated, till, at the distance of a hundred 

feet from the topmost stratum, the rock turns to a sort of loose shale, which crumbles to 

pieces under the touch; and is rapidly worn away by the action of the violent blasts of wind, 

rising out of the pool into which this enormous cascade is projected.

In process of time, as the lower strata are fairly eaten or worn away, the upper part of the 

rock must be left without a foundation. But owing to the tough nature of the upper.strata, 

they continue to project a long way over before they break down. There must come periods, 

however, every now and then, when the overhanging rock, with such an immense load of 

water on its shoulders, will give way, and the crest, or edge, of the Pall will recede a certain 

distance. At the time of. our visit, the top of the rock, or that over which the river was 

directed, overhung the base, according to the rough estimate I made, between 35 and 40 

feet, thus forming a hollow space, or cave, between the falling water and the face of the rock.

While the above lines were actually in the printer's hands, my eye was accidentally caught 

by the following paragraph in a newspaper: 

"NIAGARA FALLS. A letter from a gentleman at that place, dated Dec. 30, 1828, states, 

that on the Sunday evening preceding, about 9 o'clock, two or three successive shocks or 

concussions were felt, th6 second of which was accompanied by an unusual rushing sound of 

the waters. The next morning it was discovered, that a large portion of the rock in the bed 

of the river, at the distance of about two-fifths from the Canada shore to the extreme angle 

of the Horse Shoe, had broken off", and fallen into the abyss below. The whole aspect of the 

Falls is said to be much changed by this convulsion. A course of high winds for several 

days previous to its occurrence, producing an accumulation of water in the river, is supposed 

to have been the immediate cause. This gradual crumbling away of the rock over which 

the Niagara is precipitated, adds plausibility to the conjecture, that the Falls were once as 

low down as Lewistown, and have for centuries been travelling up towards their present 

position."

Captain Hall also published a series of sketches of the falls/ and as 

these were made with the camera lucida they have exceptional value. 

They, in fact, constitute the first record bearing on the rate of recession from which measurements can profitably be made, and there is 

frequent reference to them in other parts of this paper.

The preceding citations serve to show the early development of 

three ideas: (1) That the crest of the Horseshoe Fall is receding 

upstream, the recession being caused by the energy of the cataract; 

(2) that the gorge below the falls was created by this process of recession, the position of the falls having originally been where the mouth 

of the gorge now is, and (3) that it is possible, by sufficiently accurate 

observations, to determine the rate at which the change is taking 

place.

Associated with the idea of measuring the rate of recession was that 

of applying it to the determination of the time consumed by the river

oHall, Capt. Basil, Forty etchings, from sketches made with the camera lucida, in North America, 

in 1827 and 1828, Cadell and Co., Edinburgh, 1829, pis. 1-5.
10 BATE OF RECESSION OF NIAGARA FALLS.

in the making of the gorge. By some of the earlier writers the age of 

the gorge was obscurely connected with the age of the world as estimated from Biblical data; by others it was recognized as a small fraction of geologic time. With the progress of knowledge of the local 

geologic history there was increasing interest in the time estimates for 

the river, and the various conditions affecting the estimate came to be 

scrutinized with much care. As developed by careful study, the 

problem proved to be complex and difficult. It came to be recognized not only that the rate of recession in different parts of the gorge 

must have varied with the height of the cataract, the temporary width 

of the stream, and the thickness of the capping limestone, which is 

different in different places, but also in a very important way with the 

volume of water carried by the river/ which has been subject to 

extreme fluctuations. The influence of these 'various conditions 

assumed prominence in the discussion, and altho the rate of present 

recession came to be fairly well known, opinions still differed widely as 

to the total period represented by the gorge. The age of the gorge is 

outside the scope of the present paper, and the subject is here mentioned 

only to show the basis of the strong interest which has been felt in the 

determination of the present rate of recession.

In 1841 James Hall, then geologist of the fourth district of New 

York, undertook the preparation of an authoritative map of the crest 

of the falls, and employed for that purpose E. L. Blackwell, a civil 

engineer. The work was completed in the autumn of 1842, at which 

time a series of monuments were established at the principal trigonometric points. The map was published the following year, a together 

with descriptions of the monuments and a table of compass bearings 

from the various trigonometric points to objects whose positions were 

determined by the method of intersection. It was the purpose of this 

survey to make definite record of the existing position of the crest 

line and connect this record with permanent monuments, so that by 

means of a similar survey at some future time the extent of changes 

might be determined. This purpose it has served. Monuments then 

placed have been used as starting points in subsequent surveys, and 

two of them are still extant.

As this work by our great master in geology marks a turning point 

in the subject the change from the vague to the definite I emote a 

few passages to show his point of view:

Among the phenomena of waterfalls and river gorges, the Cataract of Niagara is justly 

regarded as holding the first rank, and as standing an index in the path of time, by which 

the influence of numberless ages upon the surface of our planet may be recorded. Its 

present, its former and its prospective conditions have engaged the investigation and speculation of many philosophers. The possible consequences of its entire reduction, and the 

drainage of the upper lakes, have excited the wonder and the apprehensions of many. The

"Nat. Hist. Now York, pt. 4, Geology, 1843, opp. p. 402.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 306 PL. II

\\RUINS OF 

^ FORSYTH'S INN

CUPOLA TABLE ROCK HOUSE

A" 

FLAG POLE o

S L A N D

DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, Director

CREST LINES OF NIAGARA FALLS

FROM SURVEYS MADE IN 1842, 1875,1886, 1890, and 1905

COMPILED BY 

W. CARVEL HALL, TOPOGRAPHER U. S. G. S.

Scale

100 0 100 200 300 400 500 600 feet

EXPLANATION

 __ Survey of 1842

 ..._..._..._..._..._Survey of 1875 

_._._._._.._._. Survey of 1886 

................:....-.-........................ Survey of 1890

 : Survey of 1905

//FOOT OF INCLINE
INTRODUCTION. 11

estimated time of its recession has sprinkled grey hairs among the fresh locks.of the young 

and blooming earth, and alarmed those who would consider her still youthful in years.

But amid all these speculations, Niagara still remains; the thunder of its cataract still 

reverberates through its deep chasms, and its ocean of waters still rolls on as, unknown to 

the white man, it rolled a thousand years ago. When we come to the investigation of facts, 

we find that, except to travellers and the aborigines, Niagara was unknown until within the 

last fifty years; and that even during this time no accurate observations have been made, 

no monument erected to determine whether the falls are retrograding or not. The testimony of living witnesses and historical evidence unite in confirming the opinion that the 

water is wearing away the rock, and that the outline of the falls has changed. From these 

general observations, it has been estimated that they have receded at the rate of about forty 

feet in fifty years. Without pretending to question the accuracy of this or any other estimate of the kind, or to establish any rate of retrogression in the falls, we may examine its 

present, and from numerous facts infer its past condition; and from these we are entitled 

to draw an inference for the future, though without specifying time.«

The foresiglit with which he planned the survey and record for the 

specific purpose is shown by the statement with which the map is 

introduced:

The accompanying map has been constructed from a very careful survey by Mr. Blackwell, giving the present position and outline of both falls, and the river banks upon either 

side. Upon application to His Excellency Sir Charles Bagot, late Governor-General of 

Canada, I was authorized to establish monuments upon the Canada shore, and was also 

kindly offered every other aid to promote the objects of the survey. These monuments, 

together with those in New-York, will enable future observers to ascertain the amount of 

recession during any given period. In places where the rock is exposed, copper bolts have 

been fixed, and in other places hewn stone monuments. The starting point for all these 

observations is a copper bolt fixed in the rock on the north side, near the edge-of the American fall. * * * &

In 1875 the second survey of the crest line was made by the United 

States Lake Survey under the direction of Maj. C. B. Comstock, 

the field work being by F. M. Towar. The United States Geological 

Survey undertook the third survey, which was made by Robert S. 

Woodward in 1886. The fourth survey was made in 1890, by A. S. 

Kibbe, under the direction of John Bogart, State engineer of New 

York, and a very full report was published. In this report the maps 

of the three preceding surveys are republished, and the crest lines 

given by those surveys are also placed on the new map. c The fifth 

survey was made in the spring of 1905, by the United States Geological Survey and the State engineer of New York, the work being done 

by W. Carvel Hall, and his report follows this paper.

The crest, lines determined by the five successive surveys are platted 

together on PI. II, and their examination demonstrates clearly the 

gradual retreat of the crest of the Horseshoe Fall. Each mapped 

crest line is, on the whole, farther upstream than its predecessor, and

«Nat. Hist. New York, pt. 4, Geology, 1843, p. 383. 

b Op. cit., p. 402.

c Seventh Ann. Kept. Comrs. State Res. Niagara for fiscal year October 1,1889, to September 30; 

1890, Albany, 1891.
12 BATE OF BECESSION OF NIAGARA FALLS.

their interspaces are roughly comparable with the time intervals 

between the making of the surveys; but each of these statements 

requires qualification. The region of maximum retreat has shifted 

from one part to another of the crest during the period of observation, - 

so that in any one part the rate of retreat has been irregular; and 

when the chart is closely scrutinized it is found that the different 

lines overlap one another at various points, so that if all of them were 

rigidly accurate their record would show that the crest line had in 

places advanced downstream, instead of retreating. In the report 

of the last survey it is suggested that some of these discrepancies may 

be explained by an actual sliding forward of upper layers of limestone 

before they toppled over the brink, but the greater discrepancies 

can not be explained in this way, and the discrepancies as a whole are 

unquestionably due to errors in the topographic work, chiefly thru 

failure to identify points previously sighted when intersecting bearings were taken. Fortunately, they are not of such character or 

extent as to impair the general conclusions to be drawn from the 

work; but they serve to caution the student against any overrefinement in the discussion of results.

The Erie Canal'is supplied with water from the.Niagara River at 

Buffalo, the Welland Canal is supplied from Lake Erie, and the 

Chicago Drainage Canal draws water from Lake Michigan. All the 

water thus diverted is withdrawn from the cataract. So also is 

water diverted from the river above the falls for factory purposes and 

for use in the generation of electricity. In recent years the diversion for electric power has rapidly increased, and existing charters 

authorize so large a draft upon the river that it has come to be recognized that the scenic value of the cataract is in peril. A vigorous 

protest has been made by lovers of natural beauty, and negotiations 

are in progress for an international agreement to check and regulate 

the economic exploitation of the river. Whatever the outcome of 

these negotiations, there is no reason to expect that the natural flow 

of the river will be restored, and it is believed that from this time 

onward the natural conditions will be so far interfered with as to 

modify the rate of recession. As the geologist is primarily interested in the natural rate of recession, the present time is opportune 

for a summing up of the data. In fact, the survey of 1905 was 

ordered in view of the change of conditions from natural to artificial. 0

a Since this paper was written it has come to my knowledge that a resurvey of the Niagara River is 

being made by the United States Lake Survey, the field work for the crest of the falls having been done 

in the summer of 1906. This will aflord an additional datum on the rate of recession, but is not likely 

to affect the computation to a material extent. The addition of one year to the period of observation 

will probably be offset by changes occurring within that year. Inspecting the Horseshoe curve in 

August, 1906, I was confident that a salient near the angle of the curve, which was recorded'by the 

surveys of 1890 and 1905, did not then exist. G. K. G.
RATE OF KECESSION OF NIAGARA FALLS. 18 

THE HORSESHOE FALL.

The Horseshoe Fall is at the head of the gorge. From its edges 

the walls of the gorge run northeastward approximately parallel. 

The American Fall is at the side of the gorge, 2,500 feet from its head, 

and is separated from the Horseshoe Fall by Goat Island. A few 

hundred years ago the two falls were together, the position of the 

united cataract being somewhere in the neighborhood of the present 

American Fall. The subsequent retreat of the Horseshoe Fall has 

had the effect of lengthening the gorge, but the American Fall has 

not in the same time made an alcove in the side of the gorge. With 

reference therefore to the question of the age of the gorge, it is the 

Horseshoe Fall whose rate of recession is important.

The chief data for the estimation of the rate of recession are the 

maps of 1842 and 1905, the time interval being sixty-three years. 

The outlines from those maps are shown in fig. 4. These data, like 

other statistical data, can. be discussed in a variety of ways and made 

to yield widely divergent results a fact sufficiently illustrated by 

earlier estimates of the rate of recession based on comparisons of the 

map of 1842 with that of 1875, 1886, or 1890. The following paragraphs therefore set forth somewhat fully the methods here used, 

with the principal considerations on which they are based.

In the lengthening of the gorge the river does its principal work 

in that part of the Horseshoe curve where the current is deepest. 

The agitation of the plunging water is there so powerful as to roll 

about the fallen blocks of limestone, using them as tools to grind the 

shale, and at the same time breaking them up and eventually washing them downstream. The scour maintains a deep hollow beneath 

this part of the fall, a hollow whose depth is greater than the height of 

the fall. (Fig. 1, p. 5.) At the sides of the channel, especially near 

the right bank, where the sheet of falling water is comparatively 

thin, the fallen blocks are not cleared away, but cumber the base of 

the cliff. (PI. X, p. 22.) As the cataract retreats it leaves behind it 

a deep channel, or elongated pool, in which the current is slow. Below 

the cataract the gorge is widened at top by the falling away of its 

banks. When the shale is exposed to the air it becomes subject to 

frost action, and for a time the limestone ledge above continues to 

be undermined, but a practical limit is reached as soon as the talus 

of fallen material covers the slopes of shale, and thereafter the change 

is exceedingly slow. The real lengthening of the gorge is along 

that portion of the Horseshoe where the sheet of falling water is 

heavy enough to clear away the debris and maintain a deep pool. 

The retreat of the cliff on either side of this portion is secondary, 

and appears to have little or no bearing on, the question of the rate 

at which the gorge is growing longer. I have therefore restricted 

attention to the central part of the Horseshoe .curve.
14 KATE OF RECESSION OF NIAGARA FALLS.

As the two. crest lines compared are irregular in outline, a certain 

confusion arises if the recession.of different parts is considered separately. At one place the recession seems to have one direction, at 

another place to have another direction, and various complications 

ensue when attempt is made to combine measurements made in 

different directions. In view of this difficulty it has appeared to 

me both convenient and legitimate to assume some one direction 

as the general direction of recession and at all points measure the 

amount of recession on lines parallel to that direction. From an 

inspection of the crest lines as wholes and in their relation to each 

other I have inferred such a general direction of recession, and 

assuming it to apply to the entire central tract of the Horseshoe, 

have drawn the system of parallel lines seen in fig. 4. There are

six of these lines, each extending 

from the crest line of 1842 to that 

of 1905. Their interspaces, according to the scale of the map, are 100 

feet wide. The average length-of 

these lines represents approximately the average recession of the 

cataract in the part where the sheet 

of falling water is heaviest. Their 

lengths are, severally, 430, 292, 260, 

276, 317, and 412 feet, giving an 

average length of 331 feet. This 

distance divided by the number of 

years, 63, gives as the average 

annual recession 5.3 feet.

A somewhat allied method of 

estimate is concerned with areas. 

Still restricting attention to the central portion of the Horseshoe 

curve, I have drawn a line from A, the point at which the two crest 

lines begin to diverge, to the opposite shore at C, making its direction lie at right angles to the general direction of recession. The 

area contained between the two crest lines AZB and AEC, and 

limited downstream by the straight line AC, may be regarded as 

the area removed by the central portion of the fall between 1842 

and 1905. The corresponding width of this part of the gorge in 

1842 was AB, 570 feet;.in 1905 AC, 760 feet. The mean of these, 

665 feet, is assumed as the average width for the intervening period. 

The indicated area between the crest lines was found by measurement 

to be 223,000 square feet, and this quantity being divided by 665 feet, 

gives 335 feet as the average recession in a direction at right angles 

to AC. Dividing, as before, by 63, the number of years, I obtain 

again as an estimate of the average annual rate 5.3 feet. O o 

FIG. 4. Outlines of Horseshoe Fall in 1842,1875, 

and 1905, with lines used in computing the 

rate of recession. The line of crosses suggests 

a position of part of the crest in 1827.
BULLETIN NO. 306 PL. Ill

HORSESHOE FALL IN 1827. 

 Capt. Basil Hall, made with camera lucida, from veranda of Forsyth's Hotel.
U. S. GEOLOGICAL SURVEY 

HORSESHOE FALL IN 1895. 

Photograph from same point as sketch, PI. 111. The island at S is common -to the two views. Their comparison sh
THE HOKSESHOE FALL. 15

The close coincidence of these two results is accidental, altho a 

general agreement was to be expected because the assumptions underlying the computations are harmonious. As already stated, materially different results may be obtained with different assumptions.

Less harmonious results are obtained if the period from 1842 to 

1905 is divided into parts and the parts are separately computed. 

Their discordance has two souses which can not be fully discriminated. From the nature of the case the rate of recession is not 

uniform. The distance to which the cornice of limestone comes to 

project before it is broken away depends not only on the strength of 

the rock, but on the local arrangement of vertical joints by which it 

is traversed, and also to some extent on the shape of the temporary 

outline of the crest. The fall of rock is therefore irregular and only 

obscurely rhythmic. In a period measured by centuries these irregularities would have little influence on the general average, but for 

short periods their influence may be great. A second source of discrepancy in the results lies in the inaccuracy of the surveys. Even 

where the sheet of water is so thin that the rock is visible thru it 

there is some liability to error, and where the topographer could see 

only the curved and changing surface of the rushing water his observations were necessarily somewhat indefinite. Two observers might 

in fact differ by several feet in their estimate of the actual position of 

the rock crest over which the water pours. The only results for 

shorter periods which it seems advantageous to place on record are 

those which use the map of 1875 .in connection with the maps of 1842 

and 1905. This approximately halves the whole period of sixty-three 

years, the earlier part being thirty-three years in length and the later 

part thirty years. By applying to these two divisions the methods 

already described for the whole period, and employing the same 

ordinates and the same limiting line, the' following results were 

obtained:

Bates of recession computed for various periods and by different methods.

Limiting dates.

1842-1875. ............................................................

1875-1905. .............................................................

1842-1905. ............................................................

Length 

of period.

Years. 

33 

30 

63

Average annual recession.

Computed 

by parallel 

ordinates.

Feet. 

4.0 

6.6 

5.3

Computed 

by areas.

Feet. 

4.4 

5.6 

5.3

The indication is that during the thirty years following 1875 the 

lengthening of the gorge went on at a somewhat faster rate than 

during a similar period preceding that date. While it is quite possible that the apparent variation in the rate is sufficiently accounted
16 BATE OF RECESSION OF NIAGARA FALLS.

for by the irregularity of the breaking away of the limestone sill, it 

is also possible that the rate has been influenced by a special condition 

.affecting the mode of recession. A change in the outline of the fall 

which was mentioned nearly a century ago as diminishing its resemblance to a horseshoe consisted in the development of an angle near 

the head of the curve and on the side toward Goat Island (Z, fig. 4). 

Within the last thirty years the recession has been especially rapid in, 

that angle, and there has developed a deep recess or notch. This 

appears to have been occasioned by a local weakness of the limestone, 

presumably its subdivision by a belt of vertical joints. Within the 

notch the mode of recession has been so far modified that the upper 

layers of limestone have been removed before the lower, so that at 

certain stages of the process the water after falling from the crest has 

been caught by a shelf. The configuration can be better understood 

by an examination of PI. I (p. 5), which is based on a photograph 

made in or near the year 1886. Whatever the method of erosion in the 

notch, it appears to be superadded to the general erosion by undermining, and an acceleration of the rate may plausibly be ascribed to it.

If we regard the general method of recession by the process of 

sapping or undermining as normal, and the influence of joint systems 

as exceptional and temporary, the rate of recession computed for the 

period from 1842 to 1875 should be accepted as normal and the best 

available for use in geologic computations; but this involves the 

assumption that the limestone ledge was not affected in other parts 

of the gorge by belts of weakness similar to the one which has been 

exposed during the last few decades. It seems to me better, on the 

whole, to assume that the limestone eroded between 1842 and 1905 is 

fairly representative, so far as strength is concerned, of all that portion of the limestone ledge in which the cataract has done its work.

The maps of 1842 and 1905 represent the earliest and latest surveys, 

but do not include quite all the data worthy of consideration in this 

connection. A sketch by Basil Hall, made with the aid of a camera 

lucida, in 1827, has a claim for accuracy by no means to be disregarded. In the use of the camera lucida the draftsman sees the 

landscape as tho faintly pictured on a sheet of paper, and at the same 

time sees the pencil with which he traces its. outlines. Before photography this method was the most accurate known for recording the 

outlines of a landscape, and in skilful hands it gives results of notable 

precision. There is much internal evidence that Captain Hall's 

sketches at Niagara were made with care and fidelity, and in view of 

these facts I have thought it worth while to endeavor to combine his 

record with the records by mapping. He tells us that his principal 

sketch of the Horseshoe Fall (PI. Ill) was made from the upper 

veranda of Forsyth's Inn, on the Canadian shore, and the relation of 

the veranda to the inn is shown by a contemporary drawing by Mrs.
BULLETIN NO. 306 PL. V

/

AMERICAN FALL IN 1827. 

made with camera lucida, from Goat Island. For explanation of broken I TIP .1 see page 19.
U. S. GEOLOGICAL SURVEY

AMERICAN FALL IN 1895. 

Photograph from balcony just above view point of PI, V.
THE AMERICAN FALL. 17

Trollope.a The inn itself long since disappeared, but its position is 

still marked by the ruins of its foundations. Thru the courtesy of 

Mr. James Wilson, superintendent of Victoria Park, who caused the 

necessary scaffolding to be constructed, I was enabled, in 1895, to 

.place a photographic camera within a few feet of the position once 

occupied by the camera lucida, and this position has also been located 

on the map of 1905 (PL II, p. 10). A comparison of the two pictures 

made from that position yielded the identification of a common point 

on one of the Three Sister Islands (S, PL III), and with the aid of the 

orientation thus secured it became possible to draw upon the modern 

map the line XY in fig. 4, representing a direction from Captain Hall's 

point of view tangent to the head of the Horseshoe Fall. It will be 

observed that this line passes very near to the head of the curve as 

drawn in the map of 1842, the implication being that at the head of 

the gorge very little recession had occurred in the fifteen years intervening between 1827 and 1842. I am not sure that this single line, 

obtained by so circuitous a method, should be allowed to influence 

the result. based on two topographic surveys, but to whatever extent 

it is given consideration its tendency is to reduce the estimate of the

annual rate.

THE AMERICAN

The recession of the American Fall is much slower than that of the 

Horseshoe. The sheet of water on its brink is comparatively thin, 

and the force the water acquires in falling is not sufficient to remove 

the larger of the limestone blocks broken from the ledge above. The 

blocks are therefore heaped at the base of the cliff and serve as a 

natural riprap to protect the shale against wear. (See PL XI, p. 22, 

and fig. 8, p. 23.) Since the Horseshoe Fall parted from the American, leaving it stranded at the side of the gorge, there has evidently 

been some falling away of the crest of the American Fall, else there 

would be no limestone blocks at its base. But as the talus increases 

in height it becomes more and more protective, and the rate of 

recession should theoretically diminish.

It has already been observed that the geologist's interest in the 

rate of recession applies primarily to the Horseshoe Fall, because the 

work of that fall makes the gorge longer. If the conditions of erosion 

had been uniform during" the whole period of the excavation of the 

gorge the work of the American Fall would have little bearing on its 

time estimates, but the volume of ttie river has not always been so 

great as at present, and there were two epochs in the history of the 

gorge when the volume was very small. During those epochs the 

discharge of the whole river was probably not much greater than the 

present discharge thru the American channel, so that the conditions

oTrollope, Mrs., Domestic manners of the Americans, vol. 2, London, 1832, frontispiece. 

Bull 306 06 2
18 RATE OF RECESSION OF NIAGARA FALLS.

affecting erosion were somewhat similar to those illustrated by the 

American Fall. For this reason it is worth while to inquire at what 

rate the American Fall has receded since the first precise observations 

on its position and contour.

Traditional information as to changes in the American Fall is summarized by Lyell: a

The sudden descent of huge rocky fragments of the undermined limestone at the Horseshoe Fall, in 1828, and another at the American Fall, in 1818, are said to have shaken the 

adjacent country like an earthquake. According to the statement of our guide in 1841, 

Samuel Hooker, an indentation of about forty feet has been produced in the middle of the 

ledge of limestone at the lesser fall since the year 1815, so that it has begun to assume the 

shape of a crescent, while within the same period the Horseshoe Fall has been altered so as 

less to deserve its name.

The graphic record begins with two camera lucid a sketches by 

Basil Hall, made in 1827. One was from Goat Island, near the 

southern end of the crest line, the other from a point on the American 

shore near the northern end of the crest line. His view points were so 

near to the fall that he was able to represent details too small to 

appear in the sketch of the Horseshoe Fall. The American Fall was 

also mapped with the same care as the Horseshoe in 1842, 1875, 1886, 

1890, and 1905. Since the time of the daguerreotype the fall has been 

photographed from positions similar to those occupied by Basil Hall, 

and in 1895 I recovered his viewpoints as nearly as practicable for the 

sake of making photographs which might be compared with his 

camera-lucida sketches. To this end I visited the localities with his 

sketches in hand, and endeavored to determine the view points by 

comparing various details of the sketches with the landscape before 

me. His sketches and the photographs are compared in Pis. V-VI and 

VII-VIII.

Examination of the combined map in PI. II (p. 10) shows that the 

outlines recorded in 1875, 1886, 1890, and 1905 run closely together, 

the plotted lines intersecting one another at various points, while the 

line of 1842 coincides for only a part of the distance. A broad 

projection near the northern shore is indicated by the map of 1842 

only, and that map also gives a more advanced position for the 

middle part of the crest line.

There is good reason to question the accuracy of the map of 1842, 

especially in the vicinity of the northern shore. The area there indicated outside the line of 1875 and later maps is 110 feet broad. As its 

position is close to Prospect Pojnt, which has been a popular view 

point thru the entire period under consideration, the falling away of 

such a body of rock, either gradually or all at once, could not have 

escaped notice, but (so far as my reading goes) current literature, 

including the literature of the guidebooks, is silent in regard to it. In

o Lyoll, Charles, Travels in North America, vol. 1, London, 1845, p. 33.
U. S. GEOLOGICAL SURVEY 

AMERICAN FALL IN 1827. 

Copy of sketch by Capt. Basil Hall, with cameia lucicla, fiom American shnre. The 
U. S. GEOLOGICAL SURVEY 

AMERICAN FALL IN 1895. 

Photograph from Prospect Point, a few feet to the left of the view point of PI. VI I. Note that the American 
THE AMERICAN FALL. 19

addition to this negative evidence, there is positive information in the 

Basil Hall sketches. Comparing his sketch from Goat Island (PI. V) 

with my photograph made from approximately the same point in 

1895 (PI. VI), it will be seen that there is essential correspondence in 

the distant headlands along the river. By means of these headlands 

I was enabled not only to establish a definite relation between the two 

views, but also to correlate the sketch of 1827 with the map of the 

gorge made in 1875, and by the aid of that map with the various 

charts of the crest line. Thru these comparisons it is shown that if 

the crest line in 1827 had had the form indicated by the map of 1842, 

its profile would have the position indicated by the dotted line A in 

PI. V, and the cataract would conceal the eastern half of the gorge 

vista. If the great salient did not exist in 1827, it could not have 

existed in 1842. The conclusion appears unavoidable that the map 

of 1842 is wholly erroneous in its delineation of that part of the crest 

line near Prospect Point.

As the Basil Hall sketches have thus served to discredit a portion 

of the map of 1842, it is in order to inquire whether they afford a substitute for the evidence ruled out. Once more using the vista down 

the gorge as the basis of correlation, and applying measurement to 

points recognized as identical, I have ascertained that the sketch of 

1827 and the photograph of 1895 give to the extreme salient of the 

American Fall almost identically the same position. At that particular point the recession appears to be zero. Nearer than the salient, and appearing about one-fourth inch to the right of it, is a peculiar configuration of the crest line which seems to be common to the 

two views. In the photograph a dark wedge projects obliquely 

downward and toward the left, interrupting the body of white. In 

the sketch .its position is occupied by a sweeping curve, less angular 

than the other lines representing the turn of the water. Making 

proper allowance for the fact that the water was unusually low in the 

summer of 1895,1 think it quite possible that these features of the two 

pictures represent the same local and peculiar configuration of the rock 

of the crest, and the suggestion they give is that there has been no 

change whatever in the crest line of that portion of the American Fall 

 since 1827.

The earliest good daguerreotype of the American Fall to which I 

have been able to assign a date is reproduced in PI. IX. The gentleman who loaned me the daguerreotype appears in the picture as a 

child, and was able by that circumstance to fortify his memory and 

say that the view was taken in 1854 or 1855. Close comparison of 

the daguerreotype with the photograph reproduced in PI. VIII, 

shows a large number of identical details ranged along the crest from 

the deepest reentrant to Luna Island, and proves that there was 

practically no recession in that part of the American Fall in the forty 

years from 1855 to 1895.
20 BATE OF EECESSION OF NIAGARA FALLS.

FIG. 5. Basil Hall's sketch of American Fall 

from Prospect Point, with lines used in transferring its directions to map. Compare figs. 6 

and 7 and Pis. VII and VIII.

In Basil Hall's view from the American shore (PI. VII) a number 

of points are sufficiently definite to be used in correlating the sketch 

with the map. Forsyth's Hotel appears on the bluff at the extreme

right. The western edge of the 

^Horseshoe Fall holds the same position as in 1842. The eastern edge 

of the Horseshoe Fall, or the righthand profile of Goat Island, serves 

as another identification point, 

altho it has doubtless fallen away 

a few feet. The crest of the American Fall where it adjoins Goat 

Island and its interruption by Luna 

Island are somewhat indefinite 

objects by reason of the curvature 

of the water profile, but are nevertheless serviceable, especially as 

their stability is assured by the general agreement of records. The 

nearer profile of the American Fall 

is assumed on the evidence just 

cited to have the position assigned 

it by the maps of 1890 and 1905. 

These points all appear on the map 

(PI. II, p. 10). The approximate 

position of the artist's viewpoint is 

suggested by the foreground, taken 

in connection with various allusions 

in the literature.

As the geometric method of making comparison between a picture 

and a map may not be familiar to 

all readers of this paper, I venture 

to explain the procedure in this 

case, adding that similar methods 

were employed in.other comparisons to which allusion has already 

been made. It is evident that the 

distance of any object in the view, 

fig. 5, to the right or left of a central vertical line depends on the 

horizontal direction of the object from the viewpoint. In order to 

show clearly the relations of the directions of the various objects, 

I drew from them a series of vertical lines by which their posiFIG. 6. Map of Niagara Falls, with lines drawn 

to various points from thctpoint occupied by 

Basil Hall in making a camera lucida sketch. 

Compare figs. 5 and 7 and PI. VII. A, Forsyth's hotel; B, western edge of Horseshoe 

Fall; C, profile of Goat Island cliff; D, crest 

of American Fall at Goat Island; E, crest of 

American Fall at Luna Island; F, extreme 

salient on crest of American Fall.
U. S. GEOLOGICAL SURVEY 

THE AMERICAN FALL IN 185- ._) R 1 '.

From a daguerreotype. To be compared with the views on Pis, VII and VIM, but the view point is farther to th

American Fall are trie same as in 1895, but the details of the Horseshoe Fall and the c'iff profile o
THE AMERICAN FALL. 21

Rock of Ages 

X

FALL S

tioris were projected against a horizontal line near the top of the 

sketch. Lines were also drawn on the map, fig. 6, from the assumed 

viewpoint to the corresponding objects, and an additional line was 

drawn in the general direction corresponding to the middle of the 

picture. Then-at right angles to the last-mentioned line, and at a 

suitable distance ascertained by- trial, a line was drawn intersecting 

all the direction lines. The map gives the projection of the various 

points on a horizontal plane; the sketch gives their projection on a 

vertical plane. The line last drawn represents the intersection of 

these two planes of projection. If 

the map and sketch are both accurate, then the points a, 1), c, etc., on 

the map should be separated by 

the same spaces as the points a, 6, c, 

etc., at top of the sketch. As a 

result of the trial a very close agreement was found as close an agreement as could be expected in view 

of the indefiniteness of some of the 

points. This agreement serves to 

verify the determination of the 

viewpoint, and also to,support the 

conclusion that the criticism previously made of the map of 1842 

is valid.

Having thus established the relation of the sketch to the map, it 

was possible to transfer the directions of other points of the sketch 

to the map. Two reentrants and 

one salient of the fall were projected upward on the sketch, giving the points g, li, and i. These 

were transferred to the line on *\e 

map representing the intersection 

of projections, and lines were drawn 

from them to the viewpoint. " These last-mentioned lines indicate 

on the map the directions of the corresponding features as recorded 

by the sketch of 1827, but do not show their distances from the 

viewpoint. They do not fix on the map the positions of the salient 

and reentrants, but assign certain limits to be observed in any 

attempt to chart the crest line as it was in 1827. They are represented on a larger scale in fig. 7. In a general way they indicate 

that there has been a small amount of recession since 1827 in various 

parts of the crest line. Such an inference, however, should not be

i

Prospect Pt.

asil Hull's 

ew point

1827

FIG. 7. Plan ol American Fall. A full line 

shows the crest as mapped in 1905; the broken 

line, as mapped in 1842; i, tangent to deepest 

reentrant as sketched by Basil Hall in 1827; 

J>, tangent to reentrant nearer Prospect Point 

1827; g, tangent to salient between two reentrants, 1827. Compare figs. 5and 6and PI.VII.
22 RATE OF BECESSION OF NIAGARA FALLS.

made without qualification, because the indicated amount of recession 

is of the same order of magnitude as the errors of survey and other 

imperfections of the data.

To give the matter quantitative statement I have tried the experiment of assuming as correct the map of 1905 and the limitations 

inferred from the sketches of 1827, and then interpreting other data 

in such way as to afford the greatest plausible recession. A computation based on these assumptions gives an average total recession 

since 1827 of 19.7 feet and an average annual recession of 0.25 foot. 

This I regard as.a maximum estimate. It is highly probable that 

the actual average rate of recession is less than this, and it may be 

much less. The idea that it is much less finds support in the identical appearance of one part of the crest in 1855 and 1905 and in the 

apparent identity of another part in 1827 and 1895.

The matter can be approached in another way. The distance 

thru which the Horseshoe Fall has retreated since it parted from 

the American Fall is about 2,500 feet. Allowing 5 feet per annum as 

the rate of recession, the parting took place about five hundred years 

ago. The condition of the American Fall at the time of separation 

may be inferred in a general way from an examination of the eastern 

part of the Horseshoe Fall at the present time (PI. X). From Goat 

Island.to a point about 500 feet westward the water is shallow, correesponding in average depth to: that of the American Fall. Beyond 

that point it is comparatively deep. In the region of deep water the 

recession of the cataract is rapid, and the portion with shallow water 

is being left behind. At the base of that part of the fall where the 

water is shallow the descending stream does not plunge into the pool, 

but strikes a talus of rock fragments. These fragments are in part 

visible, and their existence is elsewhere inferred from the forms given 

.to the spray by the reaction. It seems to me legitimate to infer that 

the American Fall at the time of its abandonment by the Horseshoe 

was not so advanced in position as to plunge into standing water, but 

had already retreated far enough to have acquired a talus above the 

level of the pool. At the present time the profile of the American 

Fall where its volume of water is greatest is approximately as shown 

in fig. 8. The edge of the main river is at S, 220 feet horizontally fr6m 

the crest of the fall at C, the intervening space being occupied by a 

gently sloping talus of large limestone blocks, among which the water 

descends in a labyrinth of cascading torrents (PI. XI). At the initial 

stage, when the American Fall was first separated, the position of 

its crest was probably at some point (I) between its present position 

and the outer edge of the visible talus. As sketched, I is 160 feet 

from C, and if the total retreat of the American Fall in five hundred 

years was 160 feet the average rate of recession was 0.32 foot per 

annum. Allowance should be made for difference in rate dependent
U. S. GEOLOGICAL SURVEY 

EASTERN PART OF HORSESHOE FALL ABOUT 

Shows talus of limestone blocks. At the left, near Goat Island, there was 
U. S. GEOLOGICAL SURVEY 

AMERICAN FALL ABOUT 1885. 

Shows talus of limestone blocks. Compare with fig. 8 in text, which represents 
THE MAP OF 1842. 23

on the gradual encroachment of the protective talus upon the 

exposed cliff of shale, so that during the earlier part of the period the 

retreat was more rapid than during the later part. The indication, 

therefore, is that the present rate of recession is considerably less 

than 0.32 foot per annum, a result in harmony with that based on the 

maps and sketches.

FIG. 8. Profile and section of American Fall near its middle part. Compare fig. 1, also PI. XI.

The assumptions underlying each of the estimates are factors of 

such importance that neither result can claim a high measure of precision. It appears to be safe to say that the present average rate of 

recession of the American Fall can not be so great as 0.5 foot per 

annum, and is probably as small as 0.2 foot per annum, or about one 

twenty-fifth.of the rate of recession of the Horseshoe Fall.

THE MAP OF 1842.

The detection of an important error in the outline of the American 

Fall as mapped in 1842 tends naturally to bring in question all other 

results of the survey of that year. Inasmuch as the outline of the 

Horseshoe Fall as determined in 1842 is one of the most important 

data used in the computation of the rate of recession, it has been 

subjected to critical examination and all practicable checks have 

been applied.

The framework of the survey includes two stations or "trigonometrical points" on the American shore, three on Goat Island, and 

three on the Canadian shore. Those on Goat Island were connected, 

each with the next, by traverse lines, distances being measured by 

the surveyor's chain and courses observed by the surveyor's compass ; so also were the two on the American shore. All other connections were made by compass bearings. From the 7 stations thus 

established the positions of 29 points on the crest lines were determined by intersections of compass bearings. In all the later surveys 

the bearings were presumably made with the engineer's transit or the 

plane-table alidade, instruments susceptible of much higher precision 

than the surveyor's compass; but in view of the shortness of the
24 BATE OF "RECESSION OF NIAGARA FALLS.

distances the relative weakness of the .surveyor's compass does not 

seem to me an important factor.

The stations and other points are indicated on the published map, 

and there is a "table of observations." With the aid of these data 

positions of points on the crest lines were replotted as a check on the 

accuracy of the compilation and engraving of the map. -This work 

revealed three errors in the bearings as published, probably to be 

ascribed to copying or printing and not affecting the map. It indicated also that the points of the crest lines determined by intersection 

are not all accurately placed on the map, the errors amounting usually 

to a few feet, but not affecting the computed rate of recession.

Each of the crest-line points was originally located, as a rule, by the 

intersection of two bearings, but there are four points to which three 

bearings were taken. In the replotting of these points the check 

afforded by the third bearing .was found to give a satisfactory result. 

The points which have the advantage of this check are all on the east 

side of the Horseshoe curve, and include the point at the angle of the 

Horseshoe in the position where the notch subsequently developed 

(Z in fig. 4, p. 14). For the remainder, or western part, of the 

Horseshoe curve there is no similar check, and the three located 

points of the crest line are so far apart as to give little mutual support. So far as the published data are concerned, these have no 

higher intrinsic, authority than the two points on the American Fall 

which have been discredited by independent.evidence.

The record <of the Horseshoe Fall which stands nearest in time to 

the map of 1842 is Basil Hall's sketch from the Forsyth Hotel. (PL 

III, p. 15), the interval being fifteen years. The general form of the 

crest line is the same in map and sketch, and the tangent based on 

the sketch is so related to the mapped crest line (fig. 4, p. 14) as to 

indicate some recession between the dates of the sketch and the map, 

but the amount of recession is less than would be expected.

The factors bearing on the estimate of the rate of recession are not 

so related that rigid mathematical methods can be applied to their 

discussion. The conflict of data and the mutual support of data can 

be weighed only by nonmathematical methods, and the result of their 

study is an opinion rather than a decision. The general tenor of the 

evidence, including the five surveys and the Basil Hall sketch, leaves 

no question that the annual rate of recession has been about 4 or 5 

feet. If full authority be ascribed to the map of 1842, the estimated 

annual rate of recession is 5.3 feet. If full authority be ascribed to 

the tangent line based on the sketch of 1827, the estimated rate is 

about 1 foot less. It is my opinion that the map affords the better 

record. Giving to it the greater weight and to the tangent a smaller 

weight, I think the best practicable estimate of the rate is between 5.3 

and 4.2 feet, but nearer to the former; and I select 5 feet partly
SUMMAEY AND CONCLUSION. ' 25

because a statement in even feet avoids the implication of high precision which might be suggested by a decimal. As an estimate of the 

average rate of recession during the period of definite observation, I 

think this can not be in error more than 1 foot.

SUMMARY AND CONCLUSION.

The data for computing the rate of recession of Niagara Falls 

include surveys of the crest line made in 1842, 1875, 1886, 1890, and 

and 1905, and camera-lucida sketches made in 1827. During the 

period covered by these data the local conditions affecting the rate of 

recession have not differed to an important extent from the natural 

conditions. The present and prospective diversions of water for economic uses interfere with the course of nature and may be expected to 

modify the rate of recession. The natural rate of recession of the 

Horseshoe Fall is desired by geologists in connection with estimates of 

the age of the river. The geologic bearing of a rate modified by 

human agency is less direct. The rate of recession of the American 

Fall is of interest to geologists because somewhat representative of 

the river's activity in gorge making when the volume of water was 

much less.

The rate of recession of the Horseshoe Fall, or the rate of lengthening of the Niagara gorge, during the sixty-three years from 1842 to 

1905 is found to be 5 feet per annum, with an uncertainty of 1 foot. 

For the thirty-three years from 1842 to 1875 the rate was apparently 

slower than for the thirty years from 1875 to 1905. The rate of recession of the American Fall during the seventy-eight years from 1827 to 

1905 was less than 3 inches per annum.

The time consumed in the recession of the falls from the escarpment 

at Lewiston to their present position, or the age of the river, is not here 

estimated. It can not properly be computed without taking account 

of all conditions, local and temporary, affecting the rate of recession, 

and some of those conditions have varied greatly from point to point 

and from time to time.
REPORT OF SURVEY OF CREST LINE.OF NIAGARA FALLS.

By W. CARVEL HALL.

In obedience to instructions from Mr. H. M. Wilson, geographer 

of the United States Geological Survey, issued in consequence of a 

plan of cooperation with Mr. Henry A. Van Alstyne, State engineer 

of New York, a survey of the crest line of Niagara Falls was made 

by me in June, 1905. The determination of the present crest line 

of the falls was desired in order that, by comparison with maps of 

earlier dates, the changes could be determined and the rate of recession computed.

Surveys of the falls of which we have record have been made as 

follows: In 1842, under the direction of Prof. James Hall, State geologist of New York; a in 1875, by the United States Lake Survey, published in the form of a chart on the scale of 1:2,500; & in 1886, by 

Prof. R. S. Woodward, then chief geographer of the United States 

Geological Survey; 0 and in 1890, by Mr. A. S. Kibbe, assistant 

engineer, under the direction of Mr. John Bogart, State engineer of 

New York.d A survey was also made in 1904 by the Electrical 

Development Company and Prof. J. W. Spencer, but the map is not 

yet published.

The great majority of the monuments recovered or established by 

Mr. Kibbe in his survey of 1890 were found to be in good state of 

preservation, but a few, one unfortunately an important one, have 

disappeared. Appended, here to are tables giving, descriptions of the 

various monuments recovered or used, together with their coordinates and the distances between them. In addition to these, there 

were used in the work temporary stations at Prospect Point, Hennepin View, Stedman Bluff, Rock of Ages, center of south chord of the 

steel arch bridge, and'the cupola of Table Rock House.

In the survey of 1842 the relations of a few points were fixt by 

traversing with compass.and chain, and the remainder of the work 

was done by compass, the positions of points on the crest being 

determined by intersection. In the surveys of 1875, 1886, and 1890

a See Nat. Hist, of New York, pt. 4, Geology, 1S43, pp. 402-404.

t> Listed by the Lake Survey as Chart No. 48.

<: Results published in Seventh Ann. Kept. Comrs. of Stite Reservation at Niagara, Albany, 1891.

<i Idem.

26
SUEVEY OF CREST LINE IN 1905. 27

directions were observed by transit instead of compass. In the 1904 

work an ingenious method was used, suggested, it is thought, by 

Mr. Goodwin, of the Electrical Development Company. He carefully 

measured the elevation of the crest of the falls and 'also of certain 

triangulation points on the Canadian bluff. Then, observing at the 

same instant for direction and for the amount of the "dip-angle," 

he computed the distance from point of observation to the crest at 

various places.

Any of these methods seems quite suitable for the determination 

of the crest at well-marked points, but the upper curve of the Horseshoe Falls has no well-marked points for observation, besides being 

masked by spray, and the methods adopted require considerable 

computation and use mainly descriptive matter for identifying even 

the most important features. As stated by Professor Woodward in 

his report already referred to 

The points on the crests of the Falls determined by the 1886 survey varied considerably 

in respect to clearness of definition and ease and precision of fixture. Some of them were 

well defined exposures of bare rock; some were less well-defined portions of rock seen 

through the curved sheet of falling water; some were indentations in such sheets, well 

defined from any point of view but presenting different aspects from different points of 

view; and some were ephemeral sprays whose identification from different points of view 

was a matter of difficulty. * * * the probable error on the crest line does not on the 

average exceed .±1.5 feet. A much greater probable error must be assigned, however, to 

the upper part of the Horseshoe Falls.

Mr. Kibbe in his 1890 report states that "for favorable locations 

on the crest of the Falls the probable error is ±1.0 foot, while along 

the deep-water portion of the Horseshoe Falls it may be somewhat 

greater."

In view of these facts, a different method was adopted in making 

the present survey, namely: T. P. No. 1 (at Prospect Point) and 

"Terrapin" (at Terrapin rocks) were accepted from Mr. Kibbe's 

survey as initial points, and were plotted to a scale of 1 inch = 200 

feet on a plane-table sheet. From these as a base all existing triangulation points were relocated, and with some newly selected points 

formed the basis of the survey. Along the American Falls and at 

the ends of the Plorseshoe Falls, by means of photographs and careful 

descriptions, numerous features were recognized, intersected, and 

plotted, and the details of the map were continuously compared with 

the corresponding natural features and their positions checked. 

Thus any discrepancy between earlier surveys and the present work 

were at once seen and examined and were thoroly tested and proved 

before the work was accepted, the majority of locations being 

determined from six to eight stations. For the upper portion of 

the Horseshoe Falls a 30-inch searchlight of very high candlepower, 

partially masked, was used to mark on the crest of the falls successive small brilliant spots of light, which were simultaneously
28 SUEVEY OF CREST LINE OF NIAGARA FALLS.

located by four transits and which it is believed should result in an 

accurate demarcation of that part of the crest.

An anomalous condition of affairs appears to be disclosed by the 

survey, similar to that noted in earlier work, viz, that certain points 

on the crest line have advanced instead of receded. This has heretofore been explained as due to discrepancies in the field work or 

inaccuracies in the delineation of the crest line between determined 

points. Doubtless these explanations hold good in all the surveys, 

past as well as present, but there is one cause of advancement and 

ultimate recession which does not appear to have been commented 

on, and which, after close questioning of numerous old residents and 

careful examination of the situation, I think is a very active element. 

It might here be emphasized that by the plane-table method used 

any discrepancy occurring was at once noticed and the new position 

most carefully checked.

In addition to the erosion caused by the spray and the chemical 

action of the water on the underlying shales, there is a'well-marked 

change in the crest line, due to the forcing off of large blocks of rock 

from the crest itself.

Approximately 20 feet below the upper level there is a waterbearing seam in the limestone, particularly well marked at Goat 

Island and above the Ontario Power Company's new power house. 

I am informed that in the winter immense, icicles form from this seam 

at various points where it is not noticeable in summer, owing to the 

quick evaporation. At about this same elevation there are at present on the American Falls four secondary cascades, or, as termed by 

the late Thomas V. Welch, superintendent of the State reservation, 

"bustles'." In my judgment these can only have been caused by 

the slipping off of a mass of rock from the crest, sliding to some 

extent on the water-bearing seam and gradually prest out by the 

force of the water and ice in slowly widening cracks upstream till, 

overbalancing, they fall, leaving the "bustles." The present survey, 

I believe, has caught some of these masses as they are being forced 

out.

This theory was discust with a number of the best-informed 

inhabitants, and while they agreed that large blocks did occasionally fall from the crest, instancing several examples, they claimed 

that in each case the fall was a sudden one, unaccompanied by any 

previous pushing forward of the mass. This forward motion, however, must be a very slow one, and would not be noticed, while the 

final fall of the rock would be assumed to be the beginning and end 

of the action.

The accompanying plan of the survey (PI. II, p. 10) shows the 

existing crest line by a solid line broken only where the flow of water 

is interrupted by overhanging rocks, and shows the earlier surveys by
TABLES. . 29

means of broken lines. Only those triangulation points which are 

permanently marked are indicated. The shore lines and the various 

permanent buildings are a compilation of all the records.

In the last few years the brink of the falls has been curtailed on 

the Canadian side by a wall 495 feet long, completely shutting off 

the Avater for that distance, and thereby reducing the length of the 

Horseshoe Falls by about one-sixth.. In recent years five power 

companies have spent large sums of money to divert a portion of the 

water now flowing over the falls to their power houses, the total 

power at present chartered being about one-fifth of all available.

I desire to acknowledge my indebtedness for material assistance 

rendered in the work to Mr. Edward H. Perry, superintendent of the 

State reservation at Niagara; to Mr. James Wilson, superintendent 

of the Queen Victoria Niagara Falls Park; to Mr. B. F. R. Paine,- 

general manager of the Ontario Power Company, and to Mr. J. W. 

Kellogg, manager of the marine sales department of the General 

Electric Company.

TABLES.

The first of the following tables includes artificial monuments and 

other permanent reference points connected with the triangulations 

of the surveys. The designation, description, and location of each 

are given, together with its coordinates as referred to Topographic 

Point No. 1 of the survey of 1842. The coordinates, with the exception of Semaphore, are taken from Mr. Kibbe's table in the Seventh 

Annual Report of the Commissioners of the State Reservation at 

Niagara, pages 105 to 107.
30 SURVEY OF CREST LINE OF NIAGARA FALLS.

List of permanent reference points.

Designation. Description. Coordinates.

T. P. No. 1........

T. P. No. 6.

Terrapin.

Loretto.

K..........

L..........

Semaphore.

O..........

1842, 1890; 1905. Stone monument 5 inches 

square on Prospect Point 1 inch below sod, 

138 feet from southwest corner stone house 

at head of incline, 145 feet frorivnorthwest 

corner of same, and 15 feet from iron lamppost.

1890,1905. Stone monument 5 inches square, 

1 foot below surface, with 6-inch terra-cotta 

tile over it, set on bluS in extreme edge of 

gravel walk at Porters Bluff, just east of 

path to the Terrapin Rocks.

1842, 1890, 1905. Stone monument 5 inches 

square, in path following top of bluff along 

southern shore of Goat Island. This monumdht projects about 7 inches and is marked 

"C" on side.

1886,1890,1905. Brass bolt 1 inch in diameter 

set in prominent square rock about 4 feet 

high, word "Terrapin" cut in top of rock 

at end of wooden walk to platform where 

Terrapin Tower formerly stood. Believed 

to coincide very nearly with point used in 

1875.

1886,1890,1905. Cross surmounting cupola of 

Loretto Convent, also brass screw one-half 

inch in diameter in the deck of cupola directly under center of cross.

1890,1905: Brass bolt 1 inch in diameter near 

superintendent's office, Canadian side, set 

in the rock 1 foot under surface of lawn and 

surrounded by 4-inch terra-cotta tile, 34.9 

feet from southwest corner main building 

and 18.3 feet from southeast corner same.

1890,1905. Brass bolt 1 inch in diameter set 

in rock between pipe railing and brink, in 

Canadian reservation, 30.2 feet from northeast corner of railing at "Ramblers Rest."

1890,1905. Stone monument 6 inches square 

between pipe railing and brink, in Canadian 

reservation, 25.4 feet northerly from pipe of 

drinking fountain south of'RamblersRest."

1890,1905. Stone monument 0 inches square, 

between pipe railing and brink, in Canadian 

reservation, a little south of "Inspiration 

Point."

1890,1905. Stone monument 6 inches square, 

marked "I" on side, set in prominent projecting point at top of bluff on Canadian side 

-about 317 feet southeasterly from south gable of Ontario power house, now in course 

of construction (June, 1905).

1890. Stone monument like last, about 400 

feet southwardly along bluff.

1890. Stone monument like last, about 490 

feet southwardly along bluff.

Center of 8-inch iron pipe sunk several feet in 

the ground on west bank railway cut about 

opposite Clarke Springs.

1890. Stone monument 0 inches square set 

into slope at Stedmans Bluff; covered in 

1900 by dry stone wall; references as on line 

between T. P. No. 1 and a nail in root of 

large leaning oak tree 21.41 feet southwest 

and 49.7 feet from nail in root of basswood 

tree.'

Feet. Feet. 

0.0 0.0

S. 1,929.1 W. 1,200.5

S. 2,370.7 W. 990.4

S. 2,044.2 W. 1,465.5

S. 3,671.4 W. 3,623.4

N. 1,021.9 W. 1,462.1

N. 788.5 W. 1,451.8

N. 193.9 W. 1,751.6

S. 458.2 W. 2,090.4

S. 1,602.5 W. 2,773.2

S. 1,934.7 W. 2,990.2

S. 2,338.0 W. 3,261.3

S. 2,496.6 W. 3,507.2

S. 989.1 W. 597.1
Distances between perm anent reference po

[Based on table of A. S. Kibbe in Seventh Ann. Kept. Comrs. S

T. P. No. 1........ ..............

M. ..............................

T. P. No. 6... .............. ..

N ...............................

B. ..............................

C... .............................

D ........:......................

I............................ ..

K. ..............................

L. ........................ . ..

O. ..............................

T. P. No. 1.

Feet. 

0.0

2,515.3

1,783.8

1,052.1

1,762.3

2, 140. 0

3 209 9

3, 566. G

M.

Feet.

0.0

4Q1 ^

T. P. NO. 6.

Feet. 

9 559 o

491.5

0.0

576.3

9 Q^fi 4

j 941 i

2, 052. 3

Terrapin.

Feet.

900 4

570. 3

0.0

2, 702. 6

i *}sn ^

1,839.4

Loretto.

Feet.

9 93(; 4

2, 702. 6

0.0

9 91fi ^

N.

Feet.

0.0

1, 607. 9