Science, Geology and Physics 



sediments upon the Archaen; third, erosion and the accumula- isoi 

 tion of earth, sands, and clays. The first witnessed the action of 

 fire; the second indicated the presence of the ocean, and the third 

 demanded the movement of enormous glaciers with the formation 

 of great lakes. 



Reality of the St. David's Channel. 



The following considerations may aid us in the belief in the 

 reality of the St. David's Channel: (1 ) The direct route is the 

 natural course of the river, and for 1 ,000 feet the water still 

 flows as in the former time. (2) The bend of the river at the 

 whirlpool is phenomenal, nothing like it has yet been described 

 among the numerous canyons of the Cordilleras. (3) The 

 character of the material in the gorge is such as implies glacial 

 transportation. At the end of the whirlpool about a hundred 

 feet thickness of sand and clay are well exposed to view, under- 

 lying red till filling the whole gorge nearly forty feet higher 

 than the flat surface of the limestone just at the outlet. This, 

 till at the trestle over Bowman's Creek, holds considerable clay 

 over a very stony mass. The creek clings to the west wall, not 

 following the middle of the gorge, as commonly represented upon 

 the Lake Survey maps. About one and a half miles northwest- 

 erly wells have been sunk a hundred feet in earth without reach- 

 ing rock. Half a mile farther, two railroads have cut deeply 

 through sand ; and at the edge of the plateau are several cuttings 

 and pits of gravel, certainly fifty feet deep. This modified drift 

 may be a mile wide. It resembles an esker; and must represent 

 the melting of a glacial tongue pushing from the main sheet up a 

 notch in the edge of the plateau. The width of the gap in the 

 rocky escarpment is about one and one-third miles. (4) The 

 west wall of the canyon has been glaciated, for fully a half mile 

 northerly from a point opposite the outlet. The smoothing and 

 striation is upon both the Niagara and Clinton limestones, with a 



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