198 LIFE OF THE PLEISTOCENE 



Toward the end of the Pliocene Period the entire country experienced a 

 considerable elevation, amounting in places to 2500 or 3000 feet, and in the 

 Grand Canyon region to as much as 6000 feet. 2 This elevation initiated a 

 fresh cycle of erosion, which was not finished at the beginning of the Glacial 

 Period. The Grand Canyon is an erosional result of this uplift. On the At- 

 lantic coast the evidences of such an uplift are found in the submerged canyon 

 of the Hudson River, which extends to the edge of the steep continental slope, 

 about 105 miles from Sandy Hook. "The outermost twenty-five miles are a 

 submarine fjord three miles wide and from 900 to 2250 feet in vertical depth 

 measured from the crests of its banks, which with the adjacent flat area decline 

 from 300 to 600 feet below the present sea level" (Upham). Spencer 3 later 

 stated that the floor of this canyon is 8736 feet below the level of the sea, 

 and the walls, at the deepest sounding, are some 4000 feet high (or deep), 

 rivaling in magnitude even the Grand Canyon of Arizona. Stoller 2 " states that 

 the Hudson from Corinth eastward flows in a channel cut in an interglacial 

 interval. "During an interglacial epoch a stream from the north, following the 

 course of the preglacial Luzerne River, was diverted from the old channel at 

 Corinth and initiated the present Hudson valley from Corinth eastward. " 



Submerged fjord outlets have been observed in the Gulf of Maine, the Gulf 

 of St. Lawrence, and Hudson Bay, at depths of 2264, 3666, and 2040 feet, re- 

 respectively. Equally striking submarine valleys have been observed on the 

 Pacific coast. Just outside of the delta of the Mississippi River a submarine 

 valley 3000 feet in depth has been located by the United States Coast Survey. 

 Similar drowned valleys are known in other parts of the country. 



An elevation of 2000 feet would raise the basins of the Great Lakes suffi- 

 ciently to provide the necessary grade for such a large river system. Spencer's 4 

 map shows a large stream, called the Laurentian River, which has its head 

 waters in the northern basin of Lake Michigan, flows thru a portion of Lake 

 Huron and Georgian Bay, thence to Lake Ontario by way of a buried channel 

 passing just west of Lake Simcoe and between Newmarket and Richmond 

 Hill; thru the basin of Lake Ontario it flows eastward at the base of a submerged 

 escarpment, and near the east end of the Lake Ontario basin it bends to the 

 northeast and enters the St. Lawrence Valley near Kingston. Two tributaries 

 join the main river in the Huron basin, one, the Huronian River, flows thru 

 Saginaw Bay and another, unnamed, flows from the St. Clair River northward. 



A large river system, known as the Erigan River, flows thru the shallow 

 Erie basin and joins the Laurentian River in the Ontario basin by a buried 



2 Warren Upham, Anier. Journ. Sci., (iii), XLI, p. 36, el seq. Spencer states that this 

 elevation may have been as much as 9,000 feet. 



ja Glacial Geology of the Saratoga Quadrangle. Bull. N. Y. State Museum, No. 183, p. 31. 



3 Amer. Journ. Sci., (iv), XIX, pp. 1-15, 1905. 



4 Falls of Niagara. 



