A GEOLOGICAL HISTORY. 67 



6th Limestone. — (See plate 7, Jig. 6.) The 

 Limestone of Niagara Falls is twenty feet thick at 

 Lewistown, where it forms the top and peak of 

 the bluff called Lewistown heights ; and is eighty- 

 feet thick at the great pitch of the great fall and 

 reposes on the shale described as 5th. This is 

 the same rock as that at Lockport, and was called 

 by Professor Eaton the " Geodiferous Lime Rock ;" 

 at that place the canal was cut through it at con- 

 siderable depth and many beautiful minerals were 

 obtained. If I understand things rightly, this is 

 the main rock that forms the basin of Lake Erie, 

 the level of whose waters is 334 feet higher than 

 Lake Ontario. If the level at Lewistown is 9 feet 

 higher than Lake Ontario, and there is a fall of 

 101 feet from the level of the great pitch, the great 

 pitch being 164 feet and the fall at the rapids 40 

 feet, and 20 feet more from the rapids to the 

 level of Lake Erie, then these sums added together 

 give the whole height of the falls 334 feet, as stated 

 above. Lake Ontario is said to be 222 feet above 

 the level of the Atlantic Ocean, which added to 

 the 334 feet, makes Lake Erie 556 feet higher 

 than tide-water ; now if a straight line be drawn 

 from Buffalo to the Telegraph at Staten Island, 

 which is the nearest point across the land to the 



