56 



tively brief time and that part of its floor which is now dry 

 ground had probably not been long abandoned by the 

 rapids when Father Hennepin saw the falls in 1678, for 

 there was still a crossfall on the west side, which as Spencer 

 has pointed out, was produced by water following a chan- 

 nel nearer the base of the bluff by several hundred feet 

 than the edge of the present rapids. 



The smaller but deeper embayment at Dufferin island 

 was made at a still later time. 



The Falls-Chippawa Buried Valley. — The rock 

 floor of the rapids above both cataracts is the eastern 

 slope of what Spencer named the Falls-Chippawa buried 

 valley. This is an old valley in the pre-glacial rock surface 

 and except where excavated by Niagara river is completely 

 buried and obliterated by the drift. Its head appears to 

 have been about at Hubbard point, the valley descending 

 gently and widening toward the south and southwest. 

 According to Spencer, the rock floor of this old valley has 

 determined the height of the falls since they passed Hubbard 

 point and the crest line of the Horseshoe fall is now 50 or 

 60 feet (15 to 18 m.) lower than formerly. It is the 

 westward sloping side of this old valley which makes the 

 rapids above the falls and it was the same circumstance 

 that caused the two larger embayments in the drift. 



The drift composing the deep filling of the old valley 

 at the falls contains a variety of deposits, including a bed 

 of old or pre- Wisconsin till at the bottom. Near Horse- 

 shoe fall this is followed by a bed of quicksand above which 

 there is a heavy bed of ground moraine. Excepting occa- 

 sional thin deposits of sand or gravel or lake clay, the 

 ground moraine is ordinarily the upper deposit of this 

 region. But the top of the bluff west of Horseshoe falls 

 and southward is a terminal moraine, called the Niagara 

 Falls moraine and made by the Lake Ontario lobe of the 

 last ice sheet as it finally withdrew from this region. 



The Upper Great Gorge. — The Gorge railway runs 

 from Horseshoe falls to Queenston, returning on the 

 American side. On the Canadian side it follows the cliffs 

 at che top of the gorge to its mouth at Queenston, 

 affording many fine views into the great chasm. On this 

 trip the gorge sections are seen in the reverse order from 



