342 Glacial Phenomena of Canada, 



the stones are scratched ; but whether the scratches made in the 

 older drift-period have not been worn away, or whether the stones 

 were scratched by river-ice is uncertain. The floor of Niagara 

 limestone is here deeply furrowed, the striations and minor 

 scratches crossing each other at various angles ; but the majority 

 run S. 30° W. They follow the general direction of the other 

 striations of the country, that underlie the drift. 



On Goat Island, Sir. Wm. Logan and I observed that the 

 fluviatile strata lie on drift, — a circumstance, I believe, not pre- 

 viously noticed. It consists, at the base, of sand ; and above, of 

 clay horizontally and evenly bedded, containing scratched stones 

 and boulders. As shown in Sir Charles Lyell's diagram*, at the 

 eastern end of the island the Niagara limestone rises a few feet 

 above the river, in the still recesses of which are numerous living 

 shell-fish. Between this and the summit of the island overlooking 

 the Falls, there is a gradual fall of 15 feet, showing the slope of 

 the river-bed when Goat Island was covered with water. The 

 drift at this point is 29 feet thick, and the freshwater beds above 

 10 feet, giving 39 feet for the height of the island above the water 

 at the edge of the Falls. Allowing a dip of 25 feet in a mile for 

 the general dip of the limestone, Goat Island was covered with 

 water when the Falls were probably about one mile and a half 

 further down than at present. With regard to the retrocession 

 of the fall, as might be expected, its rate is fastest when the body 

 of falling water is greatest, this cause of waste being far more 

 powerful than the winter's frost. Towards the base of the edges 

 of the Horse-shoe Fall, and the American Fall, blocks of limestone 

 are accumulated in great heaps, while in the middle of the Horse- 

 shoe Fall the turmoil is so great that it scoops out the shale be- 

 neath so deeply that the great fallen blocks are lost in the abyss. 

 Where the body of water is small in the American Fall, the edge 

 has only receded a few yards (where most eroded), during the 

 time that the Canadian Fall has receded from the north corner o£ 

 Goat Island to the innermost curve of the Horse-shoe Fall. 



* Travels in North America, vol. i. p. 20. 



