THE MOUNTAIN. 85 



are built. In the upper part of the group there is a mass 

 of red shale and a series of yellow, bluish, olive, and choco- 

 late slates with limy layers, which is the passage of this 

 mass into the next Formation above, a limestone. 



These layers are full of fossil shells and encrinites, and it 

 is one of these bands which has been altered into the prin- 

 cipal stratum of ore, of which, however, there are several. 

 In some places the Formation is 2000 feet thick ; at the 

 bases of the mountains of Formation 4, it is from 600 to 

 900 feet thick. 



The Formation is especially interesting to the geologist, 

 on account of the great abundance of fossils which it con- 

 tains. It is nearly on the same horizon as the Niagara 

 limestone of the New York survey. 



FORMATION 6. 



This is a limestone group, with some intermingling of 

 other elements. It contains argillaceous, magnesian, and 

 siliceous layers ; the former, where it passes into the rocks 

 below, and the latter, where it mingles with the formation 

 above, or No. 1, a sand group. It is full of fossils, pre- 

 senting a great variety of corals, encrinites, and shells. 

 Many of the strata appear to be almost entirely composed 

 of organic remains. This is the equivalent of the cliff lime- 

 stone of the Western geologists. It ranges through all the 

 valleys of denudation, with 



FORMATION T 



Which is a sandstone mass, composed of coarse-grained, 

 loosely-accreted, yellow and white sand layers. It is full of 

 fine casts of shells, and also a variety of corals, among which 

 are beautiful stone lilies. Where this Formation is exposed 

 to gradual erosion and denudation, it washes away irregu- 

 larly, leaving columns of the harder part of the rock stand- 

 ing like strange and grotesque productions of art, called 

 "Pulpit Rocks," etc. 



