CARBONIFEROUS LIMESTONE. Ill 



Sand rock 5 ft. 2 in. 



Gypsum 5 " 



Sand rock 6 " 



Shale 2 " 6 " 



Gypsum 5 " 



Blue shale 4 "6 " 



Hard, flinty rock 6 " 



Gypsum 6 " 



Shale, blue 4 '' 6 " 



Pyritous rock 8 " 



White sand rock 55 " 



Blue shale 6 " 



Total 236 " 



There is an ample flow of mineral water from this spring, quite as 

 pleasant to drink as that from Mr. Powell's well, but it is not a water 

 fit for brewing purposes, to supply which the boring was originally 

 intended. 



The upper calcareous division of the carboniferous limestone se- 

 ries is, at Grand Rapids, directly superimposed on the gypsiferous 

 shale formation ; the beds of transition from one to the other could 

 formerly be seen' in the river at the foot of the rapids, but at 

 present all that part is filled up and covered over with large build- 

 ings. 



The approximate thickness of the limestones at Grand Rapids is 

 50 or 60 feet ; the lowest beds are in streaks mingled with sand 

 granules or alternating with thin seams of sand rock ; the higher 

 are free of arenaceous admixture, and are stratified in moderately 

 thick beds, which contain some fossils and many druse cavities filled 

 with brown-colored spar crystals. Most observable among the 

 fossils are large fish-teeth, various forms of Fenestella, Polypora, 

 Trematopora, Lithostrotion mamillare, and a few Brachiopods. 

 In a few quarries, close to the west side of the river, these strata 

 can be seen. Formerly they were more extensively exposed 

 in the river bed and in the banks on the east side, but by the erec- 

 tion of dams across the river and of buildings along its sides, nearly 

 all are now hidden from observation. Next above these massive 

 beds, which serve a good purpose as a building material for rough 

 walls, follow thinner-bedded limestones interlaminated with calca- 



