66 A GEOLOGICAL HISTORY. 



irregular bar similar to this across the Licking 

 river in Kentucky, which at high-water shows all 

 the same phenomena, but on a smaller scale. 



3d Red Marl and Sandstone. — (See plate 7, fig. 

 3.) Seventy feet thick ; of this it is said the 

 upper layers only are hard. 



4th Limestone. — (See plate 7, fig. 4.) Twenty 

 feet thick. 



5th Shale.* — (See plate 7, fig. 5.) Eighty feet 

 thick. This shale is of much interest in a Geolo- 

 gical point of view, as its softness causes it to be 

 washed out of its bed from under the falls, leaving 

 the Limestone (see 6th below) above, to hold up 

 itself until a certain projection is formed, when 

 by its vast weight it falls down in the abyss below. 

 This debris is carried down the stream and is 

 somewhat levelled on the bottom of the river. As 

 the dip of this shale is descending towards Lake 

 Erie, it must sink far below the influence of any 

 water before it arrives at the boundaries of the 

 Lake, so that Lake Erie will not be drained as 

 soon as some of our very wise and flowery writers 

 on Geology have imagined. I refer to those who 

 write the romance of the science, prophecying 

 miracles and making wonders as they go. 



* This is another of these general names for any rock which has a 

 slaty structure, and is not slate proper. 



