NIAGARA FALLS AND VICINITY II3 



face, as at the whirlpool on the Canadian side, at the fall of Muddy 

 brook, and near Clifton, these fossils are generally weathered out in 

 relief. They are however not readily separated from the rock. 

 Many of the geodes still show traces of coral structure, which is 

 sometimes shown in the included gypsum. 



The limestone is well exposed in the clifif at Goat island, where it 

 has a total thickness of about no feet. The contact between the shale 

 and limestone can be seen near the entrance to the Cave of the 

 Winds, where it is about a foot above the top of the stairs. The roof 

 of the Cave of the Winds is formed by the crystalline crinoidal lime- 

 stone, the same bed which forms the roofs of all the minor caverns 

 .along the gorge. The cement beds, about lo feet thick, together 

 with the 70 feet of Rochester shale, are removed by the spray to a 

 depth of perhaps 30 or 40 feet, the floor of the cave being probably 

 on the upper Clinton limestone, thus making the hight of the 

 cavern 80 feet. Floored and roofed by resisting beds of crystalline 

 limestone, this great cavern is a fit illustration of selective erosion by 

 falling water on rocks of unequal hardness. 



The massive limestone which forms the vertical cliff of Goat island 

 IS 68 feet thick, its base being on a level with the foot of the Biddle 

 stairway. The top of this cliff marks approximately the level of 

 the falls on either side of Goat island, which therefore have a total 

 thickness of nearly 80 feet of limestone, of which however the lowest 

 10 feet yield to erosion as does the underlying shale. We may thus 

 say that at the falls there are 70 feet of resistant limestone on top, 

 .and 80 feet of yielding shales and limestones below. As the crest of 

 the falls approximates 160 feet above the river below, at least 10 feet 

 of Clinton limestone are found above the water level. 



From the top of the vertical cliff at Goat island a sloping bank 

 exposing thin bedded limestones, overlaid by about 10 feet of shell- 

 bearing gravels, rises to a hight of about 40 feet, while on either 

 side of Goat island these thin bedded limestones form the rapids 

 above the two falls. As the total hight of the rapids is about 50 

 feet, and, as they are formed along the strike of the beds owing to 

 the right-angled turn in the river at this point, the thickness to be 

 added to the known limestone mass is not over 50 feet, giving a total 

 thickness of 130 feet of Hmestone exposed within this region. 



