134 LOWER PENINSULA. 



grained, greenish-white sandstone in thick, even beds, identical with 

 the sand rock found in the first section intermediate between the 

 two coal seams. This rock is quarried and worked into cut-stone, 

 window and door sills ; it is of fine quality, better than any of the 

 coal-measure sand rocks I had seen before. The beds at one end 

 of the quarry are much thicker than at the other, and seem to 

 wedge out. Under the quarry-stone a foot or two of arenaceous 

 shales, laminated by black, coaly seams, follow, and then a coal 

 bed 15 inches thick. The coal is of very good quality, even for 

 blacksmiths' use, and is occasionally obtained by working the quarry 

 for its sand rock. The coal seam rests on bluish arenaceous shales, 

 and, lower, beds of sand rock form the base of the bluff and the 

 bed of the river. The banks of the river, at intervals for the 

 distance of 8 miles, present more limited outcrops than those near 

 Grand Ledge, but after that no more rock is denuded in the 

 river-bed until Ionia township is reached, where, in Section 23, the 

 upper sand rock of the coal measures comes to the surface, or is 

 only covered by a thin coating of drift. The quality of this sand 

 rock is superior to the equivalent beds at Grand Ledge or at Jack- 

 son ; it can be quarried in blocks of large dimension, and is of 

 proper durability for building purposes. It has a reddish tint or 

 is a variegated red and white. In the quarries I observed an 

 interesting example of discordant stratification. The surface of 

 a sand-rock ledge is seen deeply eroded by furrows and excava- 

 tions as if it had been a long time exposed to the action of the 

 atmosphere, and this eroded surface is coated with a smooth, argil- 

 laceo-ferruginous cuticle. On this ledge another deposit of sand 

 rock follows, which fills out all the inequalities of the lower bed. 

 We must, therefore, suggest a temporary emergence of the lower 

 stratum before the next ledge could be deposited over it. From 

 Mr. Blanchard, of Ionia, I received the record of a boring in the 

 vicinity of the quarries, made to a depth of 450 feet. It pene- 

 trated in 



Sand rock 80 to 1 10 ft. in thickness. 



Shales and fire-clay 4 ft. 



Coal from 20 in. to 4 " 



Fire-clay 2 " 



Sand rock, fine-grained 40 " 



Coal seam, thickness unknown. 



