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NIAGARA FALLS: 
 
 u 
 
 PHYSICAL CHANGES, 
 
 THE GEOLOGY AND TOPOGRAPHY 
 
 THE SURROUNDING COUNTRY. 
 
 1- 
 
 BY JAMES HALL, 
 M 
 
 State Geologist of New York ; Corresponding Member Bust. Soc. Nat. Hist., &c. 
 
 [From the Boston Journal of Natural History.] 
 
 ^'•A 
 
 /?vy 
 

NIAGARA FALLS. 
 
 The cataract of Niagara and the geology of the surround- 
 ing country, have been often described ; but beheving that 
 there are many facts unnoticed, and others which have not 
 had due weight in these considerations, I shall venture a fur- 
 ther attempt at illustrating some important points regarding 
 this great finger post in the path of time. I am far from 
 asserting that the problem regarding the recession or the for- 
 mer condition of this great cascade is settled. So many dis- 
 turbing causes are constantly jiresenting themselves, that al- 
 though the great principles may be deemed established, yet it 
 is impossible to calculate accurately the effect of these minor 
 influences. Every fact recorded of the past, the present, or 
 the future condition of this cataract will aid in the calculation 
 of the final result, which, some thousands of years hence, 
 may be made with tolerable accuracy. In the mean time we 
 must content ourselves with observing these facts and laying 
 down land-marks for the guidance of those who may follow 
 us in the attempt to decide the eflect of time upon these an- 
 cient rocks. 
 
 A striking feature in the Topography of western New York, 
 is the great diffei-ence of elevation between the Lakes Erie 
 and Ontario, when taken in connexion with the generally 
 level or but slightly uneven surface of the country, and where 
 there are no disturbances among the strata. The difference 
 of elevation between the other great lakes is comparatively 
 small, although Superior is situated in a disturbed geological 
 region. The elevation of Lake Erie is three himdred and 
 thirtyfour feet above Lake Ontario, and the greater part of the 
 difference is overcome by Niagara river in the sjjace of one 
 mile at the rapids and falls. 
 
 The barrier at the outlet of Lake Erie is formed by a ter- 
 race of limestone which extends from the Hudson river, west- 
 
4 HalVs Remarks on Niagara Falls 
 
 ward far into Canada, forming for many miles the northern 
 boundary of the lake. The southern slope of this terrace or 
 platform of limestone passes off beneath the water, forming 
 the bed of the lake. This terrace terminates abruptly on the 
 north, within a short distance of the lake, and we descend 
 into a low, level country, underlaid by marks and shales of 
 the saliferous formation, which extend for a distance of fifteen 
 or eighteen miles. Beyond this, there is an almost impercep- 
 tible ascent for eight miles, when it suddenly plunges down 
 about 250 feet, over the outcropping edges of various strata, 
 which here terminate abruptly, to the low table land, border- 
 ing Lake Ontario. From the base of this escarpment, the 
 country slopes almost imperceptibly to the level of the lake, 
 seven miles distant, and one hundred and twenty feet lower. 
 A great portion of the country for twenty miles north of the 
 first terrace, or that bordering Lake Erie, is so level that a 
 rise of the Niagara river for thirty feet, would inundate an 
 extent of thirty miles on both sides. After leaving the level 
 country, the ascent, as before stated, is very gradual to the 
 north ; but when we arrive at the edge of the great terrace of 
 Lewiston and Q,ueenston, the elevation is thirtyeight feet 
 above the level of Lake Erie. The general outline of this 
 part of the country will be seen in the section from Erie to 
 Ontario. 
 
 This great terrace or platform is known in New York as 
 the mountain ridge, and in Canada as Q,ueenston heights. It 
 extends to the westward of Niagara river, beyond the head of 
 Lake Ontario, and eastward beyond the Genesee river, where 
 it merges in the general level of the country ; partially from 
 the dip of the rocks in that direction, and partially from the 
 thinning of some of its members. The abrupt termination 
 of the various strata in the face of this cliff, prove conclusively 
 the extent of denuding action upon this portion of the coun- 
 try. The basin of Ontario, on the north of the terrace, has 
 evidently been excavated from the sedimentary strata, the 
 limit of deiuiding agency and that of the lake basin being 
 the line of this escarpment. The edge of this escarpment is 
 indented by numerous ravines or gorges, extending to a great- 
 
and the Geology of the Surrounding Country. 5 
 
 er or less distance ; they usually present a broad opening to 
 the north, and terminate at a point within the first mile, and 
 generally within a shorter distance. The streams now flow- 
 ing in these ravines, evidently had little or nothing to do 
 with their excavation, as the space is partially filled with 
 drift, a deposit from another source. These indentations are 
 doubtless in part the etfects of the great denuding agency 
 which produced the escarpment, by undermining and remov- 
 ing the different materials. 
 
 It has been supposed by some, and Dr. Daubeny has 
 adopted the opinion, that the terrace or escarpment at Lewis- 
 ton was produced by a fault ; either an uplifting of all the 
 strata on the sonth, or a downthrow of those on the north. 
 Not having Prof. Daubeny's paper before me, I cannot state 
 his arguments, but whatever they may be, they are certainly 
 unsupported by facts. The strata are all visible in either di- 
 rection, and there is no evidence of even the smallest disturb- 
 ance. 
 
 The strata, as they are exposed in the terrace of Lewiston 
 and Q,ueenston, and in the banks of the river on either side, 
 are exhibited in the section on the next page. 
 
 There is here not only no evidence of a fault causing the 
 difference in elevation, but direct proof to the contrary ; the 
 soft marl and shale, forming the base of the cliff in the river 
 banks, underlies the plateau from this place to Lake Ontario, 
 and is visible, almost continuously, for the whole distance. 
 On the other hand, there are the most unequivocal proofs of 
 denuding action, and that the whole basin of Ontario is due 
 to the excavating power. It will be seen that the character 
 of the strata is such as to ofter great facilities for the operation 
 of such an agent, consisting of alternating hard and soft beds. 
 The action of water would undermine the harder, and leave 
 them to fall by, their own weight, while the softer materials 
 were removed. The denudation of such extensive districts, 
 could only have taken p.lace while the country was submer- 
 ged, and during the period of its elevation from beneath the 
 ocean. This principle has been recognized by Mr. Hayes, in 
 his description of the " Geology and Topography of Western 
 
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HalVs Remarks on Niagara Falls. 7 
 
 New York,"* By adopting this mode of explanation, we are 
 enabled to account for the existence of this and similar terra- 
 ces, along the lines of bearing of our extensive limestone 
 formations, as well as for the deep valleys of ancient origin. 
 
 The strata forming the escarpment at Lewiston, as seen in 
 the section, are those through which the chasm of the Niaga- 
 ra is excavated. The whole dip gradually to the south, and 
 all below No. 8, disappear below the level of the river before 
 reaching the falls, as may be seen by the dotted line bed which 
 represents the surface of the river below the falls. The strata 
 above this line are those excavated to form the channel of the 
 river. The limestone forming the summit of the terrace, and 
 at its margin not more than twenty feet thick, gradually in- 
 creases from the addition of higher layers, till at the falls it 
 has acquired a thickness of one hundred and twenty feet. 
 This limestone, about one mile south of the falls, disappears be- 
 neath the surface, and is succeeded by a soft marl of a bluish 
 or greenish grey color, with purple bands. This formation, 
 which is a continuation of the Onondaga saliferous group, 
 occupies all the level country from two miles south of the 
 falls, to Black Rock, a distance of eighteen miles by the 
 course of the river. This is succeeded by the water limestone 
 and Helderberg limestone group. The saliferous formation, 
 occupying this great breadth of country, and forming an im- 
 portant item in any calculation regarding the recession of the 
 falls, has nevertheless always been overlooked by observers, 
 and its existence in that part of the country was never noticed 
 by any one, till the publication of the New York Geological 
 Reports, in 1838. Previously, all the distance between the 
 falls and Lake Erie was considered as underlaid by limestone ; 
 and the limestone of Black Rock, or the Helderberg group, 
 was placed immediately above the Niagara limestone, and 
 represented as resting upon it. 
 
 The Niagara river, in its escape from Lake Erie, has exca- 
 vated a passage through the Helderberg limestone, (No. 10,) 
 which forms the upper terrace before noticed, leaving a small 
 
 • Am. Journal of Science, Vol. XXXV. No. I. 
 
6 Hairs Remarks on Niagara Falls 
 
 island, known as Bird's Island, in the midst of the stream. 
 From Black Rock to within two miles of the great fall, the 
 cliannel is excavated in the rocks of the saliferous group, the 
 descent in this distance being only fifteen feet. About one 
 mile south of the fall, the Niagara limestone approaches the 
 surface, and forms the commencement of the rapids. The 
 current, for the first two miles after leaving the lake, is 
 very rapid ; after this distance, it flows on more gently, the 
 channel gradually widening as far as Grand Island, where it 
 is nearly two miles wide. It then divides, the greater quan- 
 tity of water running on the west side of this island. There 
 are several small, low islands in the river, above Grand Island, 
 but this is far larger than all of them. Below this island the 
 river expands to a width of two or three miles, and presents 
 all the appearance of a quiet lake with small, low islands. 
 Approaching the rapids, the river narrows, and the current 
 becomes more rapid, and for about one mile before reaching 
 the grand cascade, rushes on with inconceivable velocity, 
 over a declivity of fifty two feet, to the edge of the precipice, 
 where it is precipitated into a gulf one hundred and sixty feet 
 below. 
 
 The chasm through which the Niagara river flows, from 
 this point to its emergence into the low country at Lewiston, 
 is excavated in the rocks represented in the section, Nos. 7 
 and 8 only being visible at the falls, the others rising succes- 
 sively from beneath the water, owing to the declivity of the 
 bed of the river, and the ascent of the rocks to the northward. 
 The sides of this chasm present almost perpendicular walls, 
 with a talus at the bottom, formed by the falling of some of 
 the higher masses. The outlet of this chasm, where the 
 river emerges into the plain at Lewiston, is scarcely wider 
 than elsewhere along its course. In some places the river 
 flows in a channel of less than two hundred yards across, and 
 again is expanded to twice that width. The breadth of the 
 chasm across the top, is nearly twice that of the channel or 
 stream at the bottom. The declivity of the bed of the river, 
 from the falls to Lewiston, is one hundred and four feet, or 
 nearly fifteen feet to the mile, which gives great velocity to the 
 
and the Geology of the Surrounding Country. 9 
 
 stream. At one place, however, about a mile below the fall, 
 and where the channel is narrowest, the stream glides along 
 with comparative quiet, while below this, where the channel is 
 broader, it is thrown into great confusion. Again, below the 
 whirlpool the surface of the river is more smooth, and the 
 current more gentle, though the channel is narrower than 
 above. The cause of these appearances, which have seemed 
 inexplicable upon the common theory, and have been used as 
 arguments against the recession of the falls, is to be sought in 
 the geological structure of the place. It will be seen that 
 below the whirlpool there are no hard rocks in the bed of the 
 river, and consequently the channel is deeper than where such 
 rocks exist. At the whirlpool, and above that place, the hard 
 sandstone. No. 2, is at and near the level of the river, and 
 consequently the channel is not worn so deep. Again, after 
 this hard mass has dipped beneath the surface, the channel is 
 excavated in softer rocks ; hence the narrow channel and 
 smooth water a mile below the falls. Near the falls, the 
 higher beds of sandstone and the Protean limestone come to 
 the level of the river, and thus cause a wider, shallow channel, 
 and more tumultuous water. Such, simply, I conceive to be 
 the explanation of the variable width of the chasm, and the 
 greater or less violence of the water. 
 
 Upon the west bank of the river, at the whirlpool, there is 
 a depression, and a deflection in the course of the river to the 
 right, as will be seen by referring to the map. Standing 
 upon the east bank of the river, this depression has the ap- 
 pearance of having been worn by the eddying current of the 
 stream ; but on farther investigation it proves to be of differ- 
 ent origin. During a recent visit, in company with Mr. Lyell, 
 Ave examined this place, and found it to be an ancient gorge, 
 filled with drift, except a narrow ravine through which a 
 small stream flows into the river. This stream may be traced 
 in a north-west direction for two miles, where it comes to the 
 level of the surrounding country. In one or two places, near 
 the river, the bed of this stream has laid bare the rocks, 
 which proves that they are not excavated so deeply as the bed 
 of the Niagara. From the termination of this ravine, upon 
 2 
 
10 HalVs Remarks on Niagara Palls 
 
 the table land, going in a north-west direction about one mile, 
 we commence descending through another deep gorge, which 
 terminates upon the plateau at the base of the escarpment, at 
 St. Davids. It will be perceived, by referring to the map, that 
 the course of the river before coming to the whirlpool, if con- 
 tinued in the same direction, would lead to St. Davids. From 
 this fact it has been inferred that there is a continuous ancient 
 ravine, filled with drift, from the whirlpool to this place. 
 This most remarkable fact has been cited as a strong objection 
 to the theory of recession by the action of the river upon its 
 own bed. Still, however, I hope to show that its existence 
 is equally an objection to the chasm having been produced by 
 the action of the sea. 
 
 If this ravine be continuous from the whirlpool to St. Da- 
 vids, and existed previous to the excavation of the Niagara 
 channel to Lewiston, it seems natural to suppose that it 
 would have taken that direction. If we suppose that the 
 undermining agency of the ocean, aided by the stream, exca- 
 vated the Niagara chasm, why would not the same agency 
 have cleared out this ancient ravine ? And if it be assumed 
 that the stream had commenced flowing by way of Lewiston, 
 then we require nothing more to account for the commence- 
 ment of the chasm. The assumption that the sea excavated 
 the present channel of Niagara, does not aid in the difficulty 
 of explaining why the ancient ravine of St. Davids was not 
 cleared out ; but on the other hand, the existence of that 
 ravine, filled with drift, is a strong argument that the Niagara 
 did excavate, of itself chiefly, its present channel. For had 
 the sea remained long enough after the filling of this ravine 
 with drift, to excavate that of Niagara, it would have removed 
 a portion at least of it, and have drained the water in that di- 
 rection. We can scarcely conceive it possible that this ravine 
 could have been filled with drift, by any means, while such a 
 stream as the present Niagara river was flowing through it, 
 and if it has, at any time, been a large water course, there 
 must have been a cessation of the stream during the time of 
 this filling up. 
 
 The most rational explanation, ar.d the one most consonant 
 
and the Geology of the Surrounding Country. 1 1 
 
 with existing facts, appears to me to be, that the ravine of St. 
 Davids was excavated by the power of the waves, aided prob- 
 ably by a stream, though it may have been a very insignificant 
 one\ That this ravine was formed previously to the period of 
 the drift, and that during this time it became filled with the 
 transported materials to such an extent that the stream after- 
 wards was unable to excavate a channel through the mass. 
 Under these circumstances, the water would find an outlet at 
 the lowest point, into the basin of Ontario ; whether that 
 point were over a surface of rock or of drift, and after the 
 channel was once commenced, it would go on deepening, un- 
 less some violent change should alter the configuration of the 
 surface. Now there is no evidence of such a change in the 
 Niagara district, and it seems more rational to conclude that 
 the stream, which may have formerly found its way through 
 the ravine of St. Davids, after the filling up of that channel, 
 took the course by Lewiston, that being the lowest point at 
 which it could find a passage to the lower country on the 
 north. It may be necessary, perhaps, to suppose a depression 
 in this direction before the water would flow there ; and such 
 a depression may have existed from causes in operation previ- 
 ously, or there may have been an indentation in the edge of 
 the terrace at this place, like those farther east, near Lockport. 
 There appears, indeed, strong reason for supposing that there 
 was a depression in the surface at the place where the river 
 now flows, before the deep channel was excavated ; there is a 
 general depression on either side, and a transverse section of 
 the river would present the appearance represented in the an- 
 nexed diagram. 
 
 The recent deposit, forming Goat Island, is upon a surface 
 lower than the top of the rapids, indicating removal of the 
 
12 HalVs Remarks on Niagara Falls 
 
 surface rock to some extent, before the period of that form- 
 ation. 
 
 I will now proceed to consider, first the objections to the 
 theory that this ravine was produced by the combined action 
 of the stream and the waves of the sea ; and next the argu- 
 ments in favor of the hypothesis that the river has excavated 
 its own channel, or by far the greater portion of it. 
 
 Examples are not unfrequent where the closing up of an 
 outlet by drift, has caused the excavation of a new channel 
 through solid rock. Perhaps the best illustration of this fact 
 occurs in the passage of the Genesee river from the upper to 
 the lower valley, from Portage to Mount Morris. The river, 
 flowing from the south as far as Portage, is suddenly turned 
 around to the opposite direction, and then again turns to the 
 north, cutting its channel for about two miles through solid 
 rock, in some parts to the depth of three hundred and fifty 
 feet. At the end of this chasm it emerges into a more an- 
 cient valley, and at a point which would communicate with 
 the river at Portage, before its deflection, by less than half the 
 distance which it has required in its present course to reach 
 this place. Now had this short space been occupied by a 
 bluff" of rock, we should easily have found an explanation of 
 the reasons why the river did not pursue a direct course. But 
 what are the facts ? This shorter space, intervening between 
 the two portions of the channel, is occupied by a deep deposit 
 of drift, rising higher than the surface of the rocks where the 
 river has found its channel. In the process of examination 
 and excavation for the Genesee valley canal it has been found 
 that this drift is of great depth, extending even beloAV the 
 level of the present bed of the river. The question presents 
 itself, why did not the stream remove the gravel and sand, 
 and make itself a channel in the shortest direction, instead of 
 going twice as far through rocky strata ? Or if we advance 
 the argument that this chaimel was excavated in part by the 
 aid of the sea, why did not this undermining agency aff'ect 
 this deposit of sand and gravel ? The truth is incontroverti- 
 ble that many streams have excavated their channels to great 
 depths in rocky strata, long after the ocean left the surface. 
 
and the Geology of the Surrounding Country. 13 
 
 Passing lower down on the Genesee river, there are other 
 places where the stream has left the old channel, now filled 
 with drift, and formed a new one, through rocky strata ; and 
 finally, at Mount Morris, it emerges into another ancient val- 
 ley from a narrow gorge bounded by mural escarpments. It 
 would be absurd to assert, that broad valleys, with sloping 
 sides, filled, or partially filled with drift, are of the same age, or 
 due to the same agency, as the narrow, deep valleys or chasms 
 with clean, rocky embankments, and containing no other loose 
 materials than those arising from the adjacent rocks. 
 
 Similar examples may be found in the outlets of Seneca 
 and Cayuga Lakes, which flow into Lake Ontario. Now the 
 course of these outlets is not in a direct line north to the 
 lake, but from Seneca it turns to the eastward, excavating its 
 course through the limestone and gypsum beds, between that 
 lake and Cayuga. From all examinations I have made, there 
 appears to be an ancient valley, filled with drift, between the 
 northern end of Seneca Lake and Ontario ; and yet, notwith- 
 standing this, the stream has excavated harder materials, and 
 taken a much more circuitous route to Lake Ontario. The 
 same explanation may be given of Canandaigua and the outlets 
 of other lakes. 
 
 As an analogous case, we may compare the ravine of St. 
 Davids and the whirlpool, with that of Iroijdequoit, a few 
 miles east of Rochester. The Genesee river, after leaving 
 the gorge at Mount Morris, flows in the bottom of an ancient 
 valley to within a short distance of Rochester, where it enters 
 a new channel. This channel is narrow, with almost perfect 
 mural banks, and nowhere contains deposits of drift. On the 
 lake shore, about two miles east of the mouth of the Genesee, 
 we find a broad and deep ravine, known as the Iroudequoit 
 bay. This ravine is excavated to an unknown depth below 
 the level of Lake Ontario. The Iroudequoit creek which 
 takes its rise in the southern part of the county, flows through 
 this ravine for a few miles before reaching the lake. This 
 ravine presents a very diflerent appearance from either that of 
 the Genesee below Rochester, or of the Niagara, and no one 
 could suppose that the present stream had ever excavated such 
 
14 HalVs Remarks on Niagara Falls 
 
 a channel. At tlie lake shore, it has a broad opening with 
 sloping sides, and appears much like a bay worn by the action 
 of the sea, while perhaps a stream was flowing in at the same 
 place. It appears very natural to suppose that this may at 
 one time have been the continuation of the ancient valley of 
 the Genesee, which was commenced south of Dansville, and 
 continued northward as the land was upraised above the sea. 
 Now had the sea ever washed the base of the cliffs at Lew- 
 iston long enough to allow of the excavation of this gorge of 
 the Niagara, we should find some evidence of its sojourn there, 
 in the shape of a beach, or rounded pebbles ; but we find 
 nothing of the kind. The continuance of a line of coast of 
 sea or lake may be determined comparatively by the charac- 
 ter of the materials along its margin ; whether they are com- 
 pletely rounded, or still much angular ; or if rounded, whether 
 the forms are very much flattened. But in the case before us 
 we find nothing at a greater elevation than the ridge road, or 
 lake ridge, which, from its nature and contained remains, must 
 have been the boundary of an ancient lake. 
 
 Other examples might be cited, but these appear to me suf- 
 ficient as an explanation of causes why the Niagara did not 
 take its course from the whirlpool through the ravine filled 
 with gravel, rather than excavate a new channel from the 
 rock. 
 
 We come now to the consideration of the argument that 
 the chasm of Niagara has been worn by the sea, previous to, 
 or during the elevation of this part of the country above its 
 level. In the absence of direct proof, we must resort to anal- 
 ogy, and relying on this mode, we find that all indentations 
 or ravines, excavated in the face of sea cliffs, have a broad or 
 trumpet-mouthed opening toward the sea, and recede abruptly 
 to a point. They never present a long, narrow ravine, of 
 equal width ; and when of a length at all approaching Ni- 
 agara, they have an opening many times broader than this at 
 Lewiston. I might cite numerous examples of ravines exca- 
 vated by the sea, aided by a stream coming in at right angles, 
 but none of these are of the character of Niagara. In such 
 cases they are broad enough to allow the stream to flow 
 
and the Geology of the Surrounding Country. 15 
 
 through the bed, leaving waterworn materials along the sides, 
 monuments of the wearing action of the waves. In the 
 Niagara chasm there are no pebbles, boulders, or gravel ; the 
 river occupies nearly the whole width at the bottom, allowing 
 a talus of angular fragments of the rocks fallen from above. 
 
 The valley of the Genesee, from Rochester to Dansville, 
 affords a good example of a ravine excavated during the 
 emergence of land from beneath the sea ; but this valley is 
 broad, and partially filled with drift, the sides sloping gradu- 
 ally and for the most part covered with deep soil, partially 
 from decomposition and disintegration of the rocks beneath, 
 but principally from trans])orted materials. 
 
 The small amount of wearing accomplished by a stream 
 during the period of our observation might incline us to 
 doubt the possibility of any body of water having excavated 
 its channel backwards for a length of seven miles, and to a 
 depth of from three to five hundred feet. But if the period 
 of one life be sufficient to admit of observation proving the 
 smallest amount of recession, then it is only requisite that we 
 should carry on the process for an indefinite period, to accom- 
 plish the utmost that we require ; or, that we extend back- 
 ward our imagination regarding time, in order to prove what 
 is already accomplished. Now it is attested, within the re- 
 corded observations of those residing in the vicinity of Niaga- 
 ra, that the falls have receded within their recollection. If 
 then it is proved that this ravine could not have been excava- 
 ted by the sea during the emergence of the land, we have 
 <mly this mode of operation left to account for its formation. 
 
 From analogous facts, we learn that it only requires an ele- 
 vation of the drift, filling up the old channel, to be greater 
 than that of the rocky strata, in order to turn the water in 
 that direction, and cause it to form a new channel. We 
 have only to suppose the ravine, from the whirlpool to St. 
 Davids, filled, as it now is, with drift, to such a height as to 
 prevent the water from flowing in that direction, and the con- 
 sequence would be, as I said before, that it would seek an 
 outlet at the lowest point along the terrace, which appears to 
 have been in the direction of Lewiston. Here the water 
 
16 HalVs Remarks on Niagara Falls 
 
 commenced the work of excavation, cutting down the higher 
 strata, and rapidly undermining and removing those below. 
 It is only necessary to refer to the accompanying section, in 
 order to discover what materials the river had to work upon 
 at this period. 
 
 It is impossible that there could ever have been a perpen- 
 dicular fall of the whole height of the cliff at Lewiston, for 
 the limestone at the top, being so much thinner than at the 
 present falls, would soon be broken down by the pressure of 
 the immense body of water precipitated over its edge upon 
 the shale below. It may even be doubted whether the shale 
 would be excavated fast enough to form a perpendicular fall, 
 and it is probable that the water would be projected over a 
 declivity of the upper shale (No. 7,) to the limestone below, 
 which together with the higher layers of the sandstone would 
 form the crest of a second fall. From this again the water 
 would be precipitated as far as the sandstone, (No. 2,) where 
 a third fall would be formed. Thus, instead of a single fall 
 of three hundred and fifty feet, we should have the whole 
 height divided into three falls, at some distance from each 
 other. In consequence of the thinness of the upper limestone, 
 that fall would recede faster than either of those below it ; 
 and the middle faster than the lower one. Even under these 
 circumstances, the wearing action would go on much faster 
 than at present. Finally, however, the recession would be- 
 come less and less rapid, from the thickening of the limestone 
 above ; and from this cause, the two lower falls having the 
 same resistance to overcome as at first, would gradually ap- 
 proach the upper, till the whole became one. 
 
 At the same time there are other circumstances to be taken 
 into consideration, and among the most important of these 
 will be the dip of the strata and the ascent of the bed of the 
 stream ; both together tending to bring the strata down to 
 the level of the water as we progress southward. This fact 
 has also an important bearing upon the rate of recession ; for 
 while a hard mass remains at a considerable height above 
 water, with a soft one below, the excavation of the softer one 
 and underminiiig of the upper hard one, tends to the recession 
 
and the Geology of the Surrounding Country. 17 
 
 much more rapidly than if the whole were of uniform char- 
 acter. Thus it must have been that the fall over the sand- 
 stone, (No. 2,) receded much more rapidly while there was a 
 considerable thickness of shale below, than when it approach- 
 ed the level of the water. This would happen after the falls 
 had retreated about three miles, or nearly to the whirlpool. 
 At this point the recession would go on very slowly for a long 
 period, for this hard mass, being at the level of the water, 
 would effectually suspend the undermining process. Even at 
 the present time the mass may be seen stretching into the 
 river from either side beyond the other rocks, and at the point 
 where it crosses, producing a fall of eight or ten feet within 
 a few rods. 
 
 After this long and almost stationary period at the whirl- 
 pool, the recession would again go on more rapidly ; soft ma- 
 terials being presented at the river level to be excavated by 
 the force of the falling water, which would thus undermine 
 the harder mass above. 
 
 When the cascade had receded to near its present position, 
 another pause similar to that at the whirlpool would occur, 
 from the approach of the higher layers of sandstone, (No. 4,) 
 and the hard limestone, (No. 6,) to the surface of the water. 
 There are various proofs of this halting, both in the form of 
 the chasm below the present fall, and from the fact that this 
 lower limestone still remains in place ; for it is seen that 
 having passed a few feet beneath the water at the cascade, 
 it supports large fragments of the upper limestone fallen from 
 above. 
 
 The conclusion then, seems inevitable, that the river has 
 been the great agent in excavating its own channel, from near 
 the escarpment between Lewiston and Queenston, to the 
 present position of the cataract ; that the recession has been 
 aided by the character of the rocks, presenting alternate hard 
 and soft strata ;— and that the descent was overcome, not by 
 one perpendicular fall, but by several, produced by the suc- 
 cessive harder layers. In support of this latter assertion, a 
 single analogous case will furnish stronger evidence than a 
 long argument. 
 
 3 
 
18 HalVs Remarks on Niagara Falls 
 
 The course of the Oak Orchard creek, in Orleans County, 
 is over the same strata, and furnishes direct confirmation of 
 the succession of falls and rapids, precisely in the manner I 
 have just enumerated. But as this is little known, I will ad- 
 duce that of the Genesee river, in its descent from Rochester 
 to Lake Ontario. 
 
 In consequence of the dip of the strata, or from its absence, 
 the hard, quartzose sandstone (No. 2,) of the Niagara section 
 does not appear in the Genesee river. On entering the river 
 from the lake, we find an open channel for five miles, where 
 the river descends perpendicularly for about one hundred feet 
 from the top of the sandstone, No. 4. The hard limestone 
 layer, or one filling the place of that at Niagara, has retreated 
 a quarter of a mile farther up the river, where it forms a fall 
 of twentyfive feet. This recession of the limestone, beyond 
 the sandstone, is owing to a mass of green shale below it, 
 twentythree feet thick, while at Niagara the same shale is but 
 four feet thick. From this place to the upper fall, about a 
 mile and a half distant, we have a rapid stream. This fall is 
 one hundred and ten feet high, and over precisely the same 
 rocks as the Niagara fall at present, viz. Nos. 7 and 8 of sec- 
 tion, the Niagara shale and limestone. The limestone at the 
 top of the fall is much thinner than that at Niagara, in conse- 
 quence of the less recession into the mass, as well as from 
 being thinner as a whole. We have here a case precisely 
 analogous to Niagara as I have supposed it to have been for- 
 merly. 
 
 Had there been a quantity of water flowing down the 
 Genesee equal to the Niagara, the upper fall would have been 
 excavated farther backward, and the lower fall, in all proba- 
 bility entirely obliterated, presenting a rapid current from the 
 upper fall to the present site of the Rochester landing. There 
 appears here positive proof that there never has been so large 
 a body of water passing down the Genesee as down the Ni- 
 agara, and the concurring testimony is to the eff'ect that the 
 wearing action has been far less. The recession of the lower 
 falls at Rochester would add little or nothing to the height of 
 the upper ; for the ascent of the river bed, and the dip of the 
 
and the Geology of the Surrounding Country. 19 
 
 strata, would cause the disappearance of the whole beneath 
 the water, before reaching that point. 
 
 In support of the hypothesis that streams do cut back their 
 channels, we may adduce sufficient evidence. An observation 
 of the last four or five years upon the waterfalls of Western 
 New York, has furnished positive evidence of their recession. 
 Among these may be noticed the falls on Jacock's run, near 
 ? Genese$, and Fall brook, a few miles further south, both of 
 which have evidently receded, from the undermining of the 
 platform over which the water is precipitated. The amount 
 during this time is very small, but sufficient to be appreciated. 
 The lower falls of Portage furnish another example of reces- 
 sion, where large masses have been removed, the channel 
 deepened, and cut backwards many feet in the space of four 
 years. 
 
 Lateral streams flowing into ravines or river courses, furnish 
 the most palpable evidence of the excavating power of water. 
 The channel of Wolf creek, which comes into the Genesee 
 through a perpendicular wall of rock, is a good example of 
 this kind, where the evidence is conclusive that the excava- 
 ting power is alone due to the stream. The junction of a 
 small stream with the Genesee, on the west side, below Roch- 
 ester, furnishes another example of this power. This stream 
 has cut its channel through soft shale for fifty feet or more, a 
 bed of hmestone eighteen feet thick, a bed of shale of equal 
 thickness, and below this another bed of limestone nearly 
 equal to the upper one. Many more examples of a similar 
 kind might be named, on the Seneca and Cayuga lakes, and 
 their valleys continued to the south. 
 
 A remarkable fact connected with these lateral water courses 
 is that their dimensions bear some proportion to their present 
 quantity of water. And although the actual quantity flowing 
 in any stream may seem insufficient to excavate its bed, yet I 
 believe, generally, the largest streams will be found in the 
 largest ravines, and the small lateral streams have always a 
 proportionately smaller channel. If in any case we find the 
 stream debouching into the lake, river, or valley, through a 
 chasm with nearly perpendicular sides, and little or no wider 
 
20 HalVs Remarks ofi Niagara Falls 
 
 than it is farther up the stream, we may infer that the action 
 of the sea has had nothing to do with its excavation. 
 
 So far as our present knowledge extends, regarding the 
 mode of excavation by streams, conjointly with the action of 
 the sea upon cliffs, I consider the question regarding Niagara 
 as settled ; both by the analogy thus afforded, and by the ex- 
 amples of streams passing over the same succession of rocks ; 
 as the Oak Orchard creek and the Genesee river. The nar- 
 rowness of the chasm from Lewiston to the site of the present 
 cascade, the nearly perpendicular sides, and the absence of 
 drift within its banks, are strong negative facts in support of 
 the proposition. The evidence that the falls are now reced- 
 ing, and the incontestible proof that they have receded con- 
 siderably since this region has been inhabited, are positive 
 facts in favor of the hypothesis. Within four years, a large 
 triangular mass has disappeared from the top of the American 
 fall, and the outline is becoming more curved. At several 
 successive periods, large masses have fallen from the table 
 rock, on the Canada side, which has considerably changed the 
 outline of the fall. 
 
 There is still further evidence that the waters of the Ni- 
 agara river have once extended much nearer to the brow of 
 the escarpment than they do at present. The nature of this 
 evidence I pointed out in my report on the fourth Geological 
 District of New York, in 1838, pages 271, 272, and 273. At 
 that time, I was not aware that the same phenomena had 
 before been noticed, though I have since learned that the ex- 
 istence of fresh water deposits in Goat Island had been men- 
 tioned some years previous. Whether the important inference 
 had been deduced from this fact or not, I do not know. 
 
 Goat Island stands upon the top of the precipice separating 
 the two falls ; it is formed by the accumulation of gravel, 
 sand, and clay, upon the surface of the limestone, and is evi- 
 dently a portion of a once much more extensive deposit. 
 Upon the southern side of this island, where there is an es- 
 carpment, the thickness of the mass is about twentyfive feet. 
 The upper half of the deposit consists of coarse gravel and 
 sand, with abundance of fresh water shells of the genera 
 
and the Geology of the Surrounding Country. 21 
 
 Unio, Cyclas, Limnea, Planorbis, Valvata, and Melania ; the 
 same both in genera and species as those now inhabiting the 
 river and lakes. The occurrence of these shells, in this situ- 
 ation, about twentyfive feet higher than the top of the fall, 
 proves the existence of a river or lake at an elevation suffi- 
 cient to allow of such a deposition, for this accumulation of 
 shells and gravel bears all the evidence of a fiuviatile deposit. 
 During the past season, in company with my friend, Mr. 
 Lyell, I re-examined this region, and upon the east side of the 
 river, in a terrace about the same elevation as Goat Island, we 
 discovered the Cyclas, Valvata, &/C. which had been thrown 
 from an excavation made several years since. At the same 
 place, a tooth and some bones of the Mastodon were discover- 
 ed eleven feet beneath the fiuviatile deposit. Farther north- 
 ward, and more than half a mile north of Goat Island, in 
 another excavation, we discovered similar shells. We also 
 noticed the continuation of this terrace, or one about the same 
 elevation, as far north as the whirlpool. We did not search 
 for shells in it at this place ; but from its character and posi- 
 tion there can be little doubt but it is a continuation of the 
 same deposit, and probably will be found to contain the same 
 shells. Now in order to raise the water of the river to suffi- 
 cient height to make this deposit, it would require a barrier 
 for the water at some distance north of the whirlpool. On 
 the other side of the river a similar terrace exists, but this I 
 have not particularly examined.* Now these banks or terra- 
 ces on either side of the river, and that of Goat Island, are 
 clearly not deposits made in this form, but the remains of a 
 once much more extensive one. During the time of its de- 
 position the river occupied this valley, having its barrier far 
 towards Lewiston. In the bed of this expanded river or lake, 
 much as it now is above the rapids, this deposit was made, 
 covering the whole extent ; but from the wearing back of the 
 fall it has been carried off, the margin only being left on 
 either side, and a small portion of the central part forming 
 Goat Island. The following diagram will exhibit the posi- 
 
 • Mr. Hayes speaks of th:^ terraces on both sides of the river, as containing 
 fresh water deposits. Amer. Journnl of Science, Vol. XXXV, No. I. 
 
22 
 
 HalVs Remarks on Niagara Falls 
 
 tion of this fresh water deposit. It is a cross section of the 
 river at the falls. 
 
 a. The terrace with shells on the eastern side. 
 
 h. Goat Island, c. The terrace on the Canada side. 
 
 d. The ancient drift. L. Limestone. S. Shale. 
 
 From its present position, it seems to have been a continu- 
 ous deposit, the greater part of which has been removed. 
 The mode of its formation can be well illustrated by referring 
 to Fig. 1, which is intended to represent what is now going 
 on above the rapids, in the broad expansion of the river. 
 a. a. represents the fluviatile deposit made by materials 
 brought down by the current, and doubtless mingled with a 
 large accumulation of shells of Unio, Melania, Anculotus, &c. 
 as these shells are abundant above the falls, and large num- 
 bers of the shells of Uniones are constantly brought down the 
 rapids during the summer season. 
 
 The single terrace containing shells is not the only one, for 
 on the eastern side, at lower elevations, there are in succession 
 two others, which seem to be remains of the deposit in the 
 river bed, as it successively excavated its barrier to the north, 
 and receded towards its present position. For the greater 
 Dart of the distance from the falls to Black Rock, on the east- 
 ern side there is a terrace or bank a few feet higher than the 
 river, which may have originally limited its waters when it 
 stood at the level indicated by the fresh water deposit of Goat 
 Island. Near Black Rock, and bordering the valley of the 
 Tonawanda, there is a terrace some twenty feet higher, 
 which appears to have been the boundary of the river or lake 
 at a still earlier period ; but with these we have, at present, 
 nothing to do. The existence of the fluviatile deposit of 
 Goat Island, and at the same level on the eastern side of the 
 
and the Geology of the Surrounding Country, 23 
 
 river, requires for its elucidation the existence of water stand- 
 ing at a level somewhat higher, in order to allow of the de- 
 posit being made in the bed of the stream. To accomplish 
 this, a barrier is required further north than the whirlpool, 
 and about the height of the surface of limestone between this 
 and Lewiston. The occurrence of successive terraces below 
 this one, proves that the drainage to the present point was not 
 effected suddenly. 
 
 There is another fact which should be noticed, as proving 
 the existence of a current from south to north, during the de- 
 position of the materials forming Goat Island. The pebbles, 
 at least large numbers of them, are of the limestone of Black 
 Rock, and the harder layers of the saliferous formation, like 
 the rock in place at the upper end of Grand Island. The 
 surface of the rock, on which the deposit forming Goat Island 
 is made, is smoothed and scratched, as are the surrounding 
 surfaces both in the rapids and on either bank of the river. 
 The deposit is of greatest thickness towards the fall, and thins 
 entirely out at its eastern extremity. 
 
 There is another indentation on the eastern bank of the 
 Niagara, below the whirlpool. This has been cited as a case 
 where the small stream coming in, is insufficient to account 
 for such an excavation. *= It occurs at the junction of Bloody 
 run and the river, and bears the strongest evidence of having 
 been produced by the common agents, frost and water. The 
 wearing action of the stream alone is probably insufficient to 
 produce this short ravine, which extends a few rods back from 
 the margin of the river bank ; but when we take into con- 
 sideration the fact that the water penetrates all the fissures of 
 the rock, and then, during fall and winter, expands by freez- 
 ing, we shall find means of explaining the mode of operation. 
 At the falls, the recession is by the undermining and breaking 
 down of the upper masses ; the action of frost is not to be 
 taken into consideration, as the water never freezes. Now I 
 consider it as an established fact, that small streams, which 
 freeze during winter, will excavate their beds more rapidly 
 
 • Am. Journal of Science, Vol. XXXV, No. I. 
 
24 HalVs Remarks on Niagara Falls 
 
 in proportion, than large bodies of water, which never freeze. 
 It appears to me that the indentation at Bloody run is not 
 greater than might be expected to have taken place while 
 the main channel receded to its present position. 
 
 Whatever facts and arguments may be advanced to prove 
 the existence of phenomena indicating the former action of 
 the sea in excavating the Niagara channel, and whatever ob- 
 jections may be advanced for or against other theories, I am 
 fully of opinion that the existence of the falls and the Niagara 
 river, in their present position, is of very recent date, geologi- 
 cally speaking. I cannot resist the belief that at some previ- 
 ous period the waters of the upper lakes were discharged into 
 Ontario at its western extremity, and that subsequently, from 
 causes which at present I have not facts sufficient to explain, 
 the course was changed, and the outlet made through Lake 
 Erie. Previous to this time, there may have been a small 
 stream flowing in the direction of the present Niagara. 
 
 We come now to consider the future recession of Niagara 
 falls, and its consequences. This is a subject on which many 
 speculations have been hazarded, but no one appears to have 
 undertaken the calculation with a full knowledge of the geol- 
 ogy of the district, or to have taken into account the many 
 disturbing influences. At the present time, the cliff" over 
 which the water is precipitated, is nearly equally divided be- 
 tween thick bedded limestone and soft, disintegrating shale. 
 It is by the action of the spray from the falling water upon 
 the shale, undermining and leaving the limestone unsupported, 
 which falls down by its own weight, that the falls recede from 
 their present position. Now if we believe the statements of 
 those who have resided at the falls, the recession has been 
 about fifty yards within the last forty years ; but from all the 
 data I have been able to obtain, it appears to be much too 
 great an estimate ; indeed, it is extremely questionable if the 
 fall has receded as many feet within that time. The central 
 portion of the Canada fall recedes more rapidly than any other 
 part, for here the greatest force of the river is exerted. We 
 know, likewise, from the testimony of all residents at this 
 place, that the American fall is becoming more curved in its 
 
and the Geology of the Surrounding Country. 25 
 
 outline, whereas formerly it was nearly in a straight line. 
 The successive descent of large masses of limestone, and the 
 still continued overhanging of the table rock, prove very con- 
 clusively the unremitting action of water and air upon the 
 shale below. 
 
 In ihe absence of established landmarks, we are compelled 
 to leave the rate of recession unsettled for the present : and 
 the only mode by which this can be determined accurately is, 
 by a systematic survey and triangulation of the form of the 
 cascade, and ihe establishment of permanent marks of refer- 
 ence for future observers. 
 
 Leaving out of view the time or rate of recession, we have 
 sufficient data to establish with certainty the future changes 
 which will supervene, allowing the recession to go on as it is 
 now doing. The lower half of the rock at the cascade, or 
 about eighty feet, is of soft shale, the limestone above being 
 of equal thickness ; higher still is about forty feet of thin, 
 bedded limestone, forming the rapids. These different rocks 
 are represented in the section as 7, 8 and 8', respectively. 
 Now these beds dip to the south at the rate of about twenty- 
 five feet in the mile, and (he declivity of the bed of the river 
 is about fifteen feet in the mile, from the falls to Lewiston. 
 It follows, therefore, that as the falls recede, there will be a 
 less amount of shale above water, owing to the dip, and to 
 this must be added the amount of declivity in the river bed, 
 both together making forty feet. So that when the fall has 
 receded one mile, the surface of the water will stand at A:., 
 or a point in the shale half way between the present surface 
 of the water and the bottom of the limestone. Going on at 
 this rate for another mile would take away from the fall forty 
 feet more of the shale, so that the surface of the river would 
 stand at p. or the base of the limestone. 
 
 The cataract would then have a solid wall of limestone to 
 wear down, the river beneath protecting, in a great measure, 
 the undermining action upon the shale. During this time, 
 and at the end of the first mile, the falls would have arrived 
 at the present site of the commencement of the rapids, and 
 thus about forty feet more of limestone would be added to 
 4 
 
26 Hall's Remarks on Niagara Palls 
 
 the height ; unless from its thin bedded character it continued 
 to recede faster, and thus continue a rapid. In this case, 
 there would be a fall of one hundred and twenty feet at the 
 end of the first mile {i, k.) ; and one of eighty feet (o. p.) at 
 the end of the second mile. 
 
 At this period, then, we are to contemplate the cataract of 
 Niagara as having receded two miles, the shale having disap- 
 peared beneath the river, and the cascade presenting a solid 
 wall of limestone eighty feet high, and a rapid of forty or fifty 
 feet (o. ')n.) beyond. The recession would then go on very 
 gradually, and so soon as masses from this cliff* have fallen 
 down to fill up the river bed, as they inevitably will in a 
 great measure, then the base will be protected so effectually 
 that little influence will be exerted by the force of the water. 
 Eventually, however, the cliff will be broken down, and huge 
 fragments piled up below, until the cataract will be nearly 
 lost amid them. This state of things will continue for a long 
 time, the height gradually diminishing, till the river has cut 
 its way back for two miles further, when there will be no 
 thick bedded limestone above water, and the higher beds will 
 form a rapid a^ before. 
 
 This point of meeting, between the surface of the river 
 and the top of the thick bedded limestone, will be about one 
 hundred feet lower than the summit of the present cascade, 
 and as there will be forty feet of rapids in the thin bedded 
 limestone within a short space, as there now is, it follows that 
 there will be added to the descent of the river beyond the 
 rapids, one hundred feet more than at present, as the surface 
 of the limestone has dipped to that amount. The whole fall 
 in the river at that time, from Lake Erie to the point of junc- 
 tion between the limestone and water below the rapids {h. o.), 
 will be about one hundred and sixty feet. The distance 
 between this point and Lake Erie is occupied by nearly uni- 
 form soft layers, and after a partial wearing down of the lime- 
 stone forming the rapids, the descent will be equally distributed 
 over the whole extent of sixteen miles, giving a uniform de- 
 clivity of about ten feet in the mile, or one third less than 
 the present declivity in the bed of the river from the falls to 
 
and the Geology of the Surrounding Country. 27 
 
 Lewiston. From the nature of the bed of the river for fifteen 
 miles below Lake Erie, it may be doubted whether this rapid 
 descent along the whole distance would be continued; for 
 the stream, having no heavy blocks of rock to remove, would 
 keep its channel clear with a far less declivity ; and should 
 this prove the case here, we might still have a fall of a few 
 feet, at the outlet of Lake Erie, over the limestone succeeding 
 the saliferous group. 
 
 Whether such a fall would occur at the outlet of Lake Erie, 
 depends on the solution of the problem regarding the acquired >•< 
 declivity in the bed of the river below Lake Erie, Which- 
 ever way it may occur it will make no material difference in 
 the great result, which will be either a continuous rapid 
 stream from Lake Erie to Lewiston, or a rapid stream with a 
 fall at the outlet of Erie. If present causes continue to ope- 
 rate as now, such will be the consummation, the finale, of 
 the grand cataract of Niagara. 
 
 It is unnecessary here to follow on this recession gradually 
 from the outlet of Lake Erie to the final drainage of a great 
 portion of its waters. The views which have been enter- 
 tained of the sudden drainage of this or any of the upper 
 lakes, and a deluging of the country on the north and east 
 are no longer considered as tenable by any one, and even 
 if Lake Erie could be drained suddenly, it would cause no 
 deluge of any importance. If the whole lake were at once 
 placed upon Lake Ontario, it would only elevate its surface 
 by about one hundred and fifty feet, so that its extent would 
 scarcely exceed the limits of the ancient lake ridge, and the 
 outlet would still be the valley of the St. Lawrence. 
 
 In calculating the future recession of Niagara falls, there 
 are many disturbing influences to be considered. At the 
 present time, by means of the Erie and Welland canals, large 
 quantities of water, which formerly flowed over the fall, are 
 returned to Lake Ontario by other than the natural channels. 
 The Illinois canal, at the southern extremity of Lake Michigan, 
 will drain a large amount of water in that direction, which 
 will find its way to the ocean through the Mississippi river 
 and Gulf of Mexico, Extensive improvements have been 
 
28 HalVs Remarks on Niagara Falls 
 
 contemplated at the falls, and the erection of manufactories, 
 by which great quantities of water from above the rapids will 
 be returned to the Niagara channel below the falls. Thus far 
 the country supplying water to the upper lakes has been but 
 little changed by the hand of cultivation, the piimeval forests 
 still cloihe the surface, and evaporation to a gieot extent is 
 prevented. This cannot always remain so ; the advancing 
 settlements will yet penetrate even the wilderness bordering 
 Lake Superior, and the opening of the sarfuce to the influence 
 of the sun's rays will greatly diminish Uie supply of water 
 flowing into the tributaries. These causes will sensibly di- 
 minish the quantity passing down the natural outlet ; and the 
 mighty Niagara, the " Thunder of Waters,'''' is destined to be 
 at certain seasons but a diminutive representative of its former 
 grandeur. 
 
 Note. Since writing the foregoing paper, I have referred to 
 some notes and correspondence with Mr. FiO]^, Government 
 Engineer at Toronto, U. C. From levels which he has made 
 from Lake Ontario to the (iueenslon heights, at several places, 
 he says the crest of the terrace constantly declines going 
 westward from the river, while the base continues at the same 
 elevation. This fact is opposed to information I had before 
 received, and to the general belief. If this be substantiated, 
 and I have every reason to believe the statement, it may ma- 
 terially alter the reasoning in regard to ihe former recession, 
 of the falls, and the manner in which the chasm has been 
 excavated. 
 
 From the Niagara river there is a declinption of the crest of 
 the terrace eastward, so that at Rochester its summit is about 
 sixtyfive feet below the level of Lake Erie ; giving in this 
 direction a descent of about one hundred feet in eight v miles.* 
 I have no data for determining the rate of declination wester- 
 ly, but whatever it may be, it proves the coarse of the Niagara 
 to be upon or near the highest part of this terrace. If this 
 inequality of the surface was produced by some force after 
 
 ' See New York Geological IlHports. 
 
and the Geology of the Surrounding Country. 29 
 
 the strata became consolidated, there might have been pro- 
 duced a rent in this direction, as in the diagram which repre- 
 sents a transverse section. 
 
 This may iiave been the first cause of directing the water 
 in its present channel, which was afterwards widened by the 
 river. There seems some reason to suppose this may have 
 been the case, from the general direction of the chasm, being 
 at right angles wifh the stiike of the strata. If this be true, 
 however, the fissure must have been extremely narrow, and 
 still have left lo the river the work of excavation, though 
 under very different circumstances. The reasoning in regard 
 to the existence of p depression previous to the excavation of 
 a deep channel, will still hold true, as well as that regarding 
 the fresh water deposits, and (he terrace extending to the 
 whirlpool. The future recession of the cataract cannot be 
 affected in auy manner by this fact, for if such a rent ever 
 existed, it seems i)ot to have extended as far as the present 
 site of the falls, for all ilie testimony is to the effect that the 
 process of retrogression goes on by the action of the water 
 upon the shale, which undermines the limestone. If there 
 was a fissure in the course of the Niagara, it did not reach so 
 deep as the bed of the river, for it seems quite certain that 
 the thick bed of sandstone (No. 2, of section,) has never been 
 excavated very deeply below the present surface of the river. 
 If these views regarding the elevation of the terrace are 
 found to hold true, it will aid in establishing the opinion be- 
 fore expressed, that the present channel of Niagara is of 
 recent date. I have long believed that the former outlet of 
 the great Lakes was by the western end of Lake Ontario, 
 though I have not been able to make investigations to the 
 extent desired in order to establish that opinion. 
 
 The period when the disturbance of the strata took place, 
 is one of great importance, and may aid in determining the 
 comparative age of the Niagara channel, and the period of the 
 drift. That the former was subsequent, however, does not 
 admit of doubt. I am not aware how far the terrace contin- 
 ues to decline westward from the Niagara river, but it is quite 
 certain that the limestone rises before going as far west as the 
 
30 Perkins^ Remarks on Fossil Bones 
 
 head of Lake Erie ; for we find crossing this lake near its 
 western extremity, an anticlinal axis which extends northward 
 into Canada, and southward entirely across the State of Ohio. 
 Now this may have happened at the same period as the disturb- 
 ance or uplift, further east, and the production of this western 
 axis may have resulted in turning the course of the outlet, and 
 the formation of the Niagara river ; but more facts are required 
 before any speculations can be offered upon this subject. 
 
LIBRARY OF CONGRESS 
 
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