96 Geology and Topography of Western New York. 



The northern boundary of the terrace, as before stated, termi- 

 nates by an abrupt precipice, rendered more rugged and forbidding 

 in appearance, by the disintegration of the shale on which it rests ; 

 causing the harder strata to project from the bank, and when suf- 

 ficiently undermined, to be precipitated to the plain below. This 

 action goes on, till the talus covers the face of the shaly strata, 

 and protects them from further disintegration. The mural preci- 

 pice above might apparently remain for ages, without suffering 

 material change. This escarpment is indented by numerous ra- 

 vines which penetrate the bank to a greater or less distance. The 

 streams which now occupy these indents, are mostly insignificant 

 in size ; while many, some of which extend far-thest back from 

 the general line, drain but a few hundred acres, and are only oc- 

 cupied by the water which oozes from their banks, except during 

 heavy rains, and the thawing of the snow at the end of winter. 

 When viewing this escarpment, it is difficult to resist the conclu- 

 sion, that the terrace once extended much farther north, and has 

 been undermined and broken down by the action of the surge. 



Not imfrequently, persons who visit the falls of Niagara, and 

 superficially examine the topography of the surrounding region, 

 conclude, that the cataract was once located at Lewiston, seven 

 miles below its present location. Full of this grand conception, 

 and without taking into the account the causes which gave rise 

 to these general topographical features, they first attempt to ascer- 

 tain its perpendicular height at that time. Having settled 'this to 

 their satisfaction, they often launch forth into a train of calcula- 

 tions, alike unprofitable and extravagant ; first to determine their 

 age, and then, the number of years they will occupy, in their 

 backward course, before they will invade the rocky ramparts of 

 Lake Erie.* But, as in the onset, the origin of the cataract, one 

 of the most important terms of the problem, is entirely omitted, 

 thek conclusions are wholly erroneous, and are entitled to as 

 little consideration, as the " baseless fabric of a dream." 



* After all, perhaps those geologists who only view the falls in theory, are the 

 most prolific in drawing such conclusions. A series of lakes, situated like this 

 chain through the centre of North America, with rocky beds which shelve gently 

 from the shore, might perhaps be drained in the course of ages, by the gradual 

 wearing down of their outlets ; but never so rapidly as to produce inundations, 

 such as are assumed to have happened, at one time or other, over most parts of 

 the earth; ahd which this hypothetical deluge, which is to inundate the fair valley 

 of the St. Lawrence, some 30,000 years hence, is cited to illustrate. 



