88 REPORT OF THE 



many, though we have not so large a proportion of Goniatiles; 

 while Trilobites and Spiriferidce are entirely wanting. Neither 

 is our fauna by any means as rich. 



The rocks of this group have been quite extensively employed 

 in the southern part of the State for building purposes, and in 

 moderate sized structures they answer sufficiently well, but for 

 very high structures the stone needs to be selected with care, 

 as some portions are too incoherent for security. For cellar 

 walls and other rough masonry they prove of gi eat utility. At 

 Jonesville and other localities the uniformly colored, homo- 

 geneous, greenish strata, in the lower part of the group, have 

 been worked into very handsome caps and sills. 



12. — Napoleon Group. 



In approaching Point au Chapeau of Lake Huron, from the 

 south, the bottom of the lake is seen to be a solid greenish 

 sandstone. At the point is an outlier containing about four 

 square rods. The section exposed here is about 8 feet. The 

 action of the waves has undermined the rock, and excavated it 

 into purgatories through which the water rushes with the hollow 

 sound described as occurring in similar situations on the sea 

 coast. In one of these purgatories the following section was 

 observed: 



4. Sandstone, reddish gray, with rusty specks, and many coarse 



grains of white quartz. 

 3. Sandstone, very thinly laminated, fine-grained, and of a dirty 



greenish color. 

 :2. Sandstone, yellowish-red, with conspicuous grains of white 



quartz, and particles of rusty matter. 

 1. Sandstone, reddish and otherwise similar to above 



All the strata exhibit oblique and curved lamination, the dip 

 of the oblique laminae being at this place toward the north, at 

 an angle of 45°. Between (2) and (3) are thin layers of bluish 

 micaceous, carbonaceous sandstone of local occurrence. 



On the east side of this point, the overhanging cliff has 

 formed a sheltered cave, in which, with some additions from 

 rude art, it is said an old hermit found a tolerable habitation 

 for several years. The rains of his stove are still visible. 



