no LOWER PENINSULA. 



larly reticulated sun cracks ; their surface is covered by thin lam- 

 inae of colorless, translucid selenite. 



Fossils I could not find in this quarry, except some small frag- 

 ments of the before-mentioned water-worn fish-bones. The thick- 

 ness of the gypsiferous rock series can not be estimated from the 

 exposures in the quarries ; by borings it has been ascertained to 

 be about i6o feet. In an artesian well sunk at the principal 

 business place of the city, in Mr. Powell's block, a lime rock 36 feet 

 in thickness was first penetrated under the drift ; then followed an 

 alternation of shales, gypsum beds, and lime-rock ledges, to a depth 

 of 204 feet from the surface. The bottom of the well is in sand 

 rock, and a fine stream of pleasant potable mineral water dis- 

 charges from the tubing to refresh the thirsty. A more detailed 

 account of a boring made in Beyrich's brewery to a depth of 236 

 feet may give an idea of the sequence of rock beds in the vicinity 

 of Grand Rapids : 



Drift 35 ft. 



Limestone i "6 in. 



Blue shales 7 " 



Gypsum i "6 " 



Blue shales 6 '' 6 " 



Flinty rock (?) 3 " 6 " 



Shale, soft 7 '' 



Blue shale, harder i " 



Shale, soft 7 '' 6 " 



Flint 2 " 6 " 



Shale 6 '' 6 " 



Pyritous rock i '' 6 " 



Shale 7 '' 6 " 



Pyritous rock i " 6 " 



Shale II " 



Pyritous rock i " 



Shale 2 '' 6 " 



Pyritous rock 2 " 



Shale 8 " 



Pyritous rock 2 " 6 " 



Sand rock 3 " 4 " 



Shale 4 " 



