148 Strict and Furrows of the Rocks of Western New York. 



the grooves, some in limestone, and others in shale. The former 

 rocks are more or less polished, and the latter smoothed, while 

 both are grooved. In the corniferous rock of Eaton, at Black 

 Rock, the nodules of flint, being much harder than the lime- 

 stone, stand up in bold relief, but are regularly smoothed like the 

 other, and the surface gradually slopes on all sides of the nodule 

 to the general level. 



1. At Upper Black Rock the course of the grooves " was found 

 by us, allowance having been made for magnetic variation, to be 

 from N. 15° 32' E. to S. 15° 32' W." Twelve feet of earth had 

 been removed from this surface. 



2. At another quarry one mile* and a half north northeast of 

 the last locality, the direction was from N. 28° 12' E. to S. 28° 

 12' W. 



3. At five miles southeast of Buffalo, on the batiks of Buffalo 



Creek, in smoothed shale, they found the grooves with the same 



general direction from the north towards the south. Mr. Has- 



kins makes the same remark on all the localities about the city 

 and in it. 



Causes. — Prom the multitude of bowlders of granite, mica 

 slate, quartz, &c. there can be no doubt that a mighty current 

 has swept from the north, and that these have been worn and 

 rounded considerably by the attrition of the materials in the wa- 

 ters. But it cannot be supposed that such a cause alone could 

 have polished the surfaces. It might smooth the rocks, as the 

 current and some attrition now do in beds of the streams : but 

 no polish is produced in that manner. After the surface had 

 been polished, such a current moving along rocks or bowlders, 

 might form the strise, furrows and grooves. 



The glacial theory offers a very simple and plausible solution 

 of both the polish and the grooves. The whole process could 

 be accomplished at one and the same time, as Agassiz and others 

 state it now to be done under and by the glaciers in Switzerland. 



The motion of a glacier by the expansion of the ice formed 

 from the water which passes into the cracks and crevices, is most 

 obvious, and entirely philosophical. One consideration, not ad- 

 verted to distinctly by the writers on the glacial theory, makes 



the subject even more palpable. It removes too the necessity of 



supposing the passage of water into those minute undulating air- 

 cells or cavities in the ice. It is this : Ice receives its greatest 



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