Science, Geology and Physics 



curious problem, would require a digression of several chapters. 1841 

 At present the shortest and most intelligible way of explaining y 

 the results of my observations and reflections on this subject will 

 be to describe the successive changes in the order in which I 

 imagine them to have happened. The first event then to which 

 we must recur is the superficial waste or denudation of the older 

 stratified rocks (from 1 to 10 inclusive, section, fig. 4, p. 37), 

 all of which had remained nearly undisturbed and horizontal 

 from the era of their formation beneath the sea to a compara- 

 tively modern period. That they were all of marine origin is 

 proved by their imbedded corals and shells. They at length 

 emerged slowly, and portions of their edges were removed by the 

 action of the waves and currents, by which cliffs were formed at 

 successive heights, especially where hard limestones (such as Nos. 

 10 and 8, fig. 4) at Blackrock and Lewiston, were incumbent 

 on soft shales. After this denudation the whole region was again 

 gradually submerged, and this event took place during the glacial 

 period, at which time the surfaces of the rocks already denuded 

 were smoothed, polished, and furrowed by glacial action, which 

 operated successively at different levels. The country was then 

 buried under a load of stratified and unstratified sand, gravel, 

 and erratic blocks, occasionally 80, and in some hollows more 

 than 300, feet deep. An old ravine terminating at St. David's, 

 which intersects the limestone platform of the Niagara, and 

 opens into the great escarpment, illustrates the posteriority of this 

 drift to the epoch when the older rocks were denuded. The 

 period of submergence last alluded to was very modern, for the 

 shells then inhabiting the ocean belonged, almost without excep- 

 tion, to species still living in high northern, and some of them in 

 temperate, latitudes. The next great change was the re-emer- 

 gence of this country, consisting of the ancient denuded rocks, 

 covered indiscriminately with modern marine drift. The upward 

 movement by which this was accomplished was not sudden and 

 instantaneous, but gradual and intermittent. The pauses by 

 which it was interrupted are marked by ancient beach-lines, 



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