CARBONIFEROUS LIMESTONE. n^ 



Carbonate of lime ^-^^.J 



" magnesia 1 1 .4 



Hydrated iron oxide and alumina 18.4 



Silicious residue 2.9 



South of Parma, in the township of Spring Arbor, the carbonif- 

 erous limestone has many outcrops ; one is on Mr. Roberts's farm. 

 Sect. 17, where a quarry was opened forty years ago by the pres- 

 ent owner for the purpose of burning lime, which in those early days 

 of settlement was a great desideratum and found a ready sale. The 

 quarries are on the slope of a hill facing south. Lowest is a sand 

 rock of light greenish color and moderately fine-grained ; part of it 

 is soft and porous, while other beds are rendered very compact 

 through an abundance of calcareous cement. In alternation with 

 the sand rock are soft, plastic, light-colored shales or arenaceous 

 shales. Above the sand rock, which in the upper ledges changes 

 into a sandy limestone, beds of a pure lime rock follow with a thick- 

 ness of from 8 to 10 feet ; some of the beds are of crystalline struc- 

 ture ; others have a smooth, conchoidal fracture, and are often in 

 brecciated condition, re-cemented by veins of calcspar. On top, the 

 brown dolomite, so often mentioned before, is found again. Fos- 

 sils are quite rare in this locality. Along the wagon-road from the 

 quarries to Jackson, several other outcrops of the carboniferous 

 limestone are passed by within the limits of Spring Arbor town- 

 ship. On Mr. Shoemaker's land, in Summit township, 3 miles south 

 of Jackson, another exposure of the carboniferous limestone can 

 be observed. At the foot of a hill sloping toward a marshy flat land, 

 there is a rather coarse-grained, whitish-green sand rock containing 

 flint concretions, and cemented hard by calcareous matter. Above 

 it are beds, still arenaceous, which should be classed as limestones ; 

 they are partially in brecciated condition, inclosing within an arena- 

 ceous, re-cemented lime-rock mass, pure limestone fragments with 

 smooth, conchoidal fracturee Still higher beds are a purer lime 

 rock, not brecciated, with some flint nodules, and crowning the sec 

 tion we find again 4 or 5 feet of the brown, ferruginous dolomite 

 rock, partly of cellulose structure, easily decaying into angular frag- 

 ments of a rough, earthy surface. The purer beds of the limestone 

 contain. 



