COAL MEASURES. 



129 



along the southern margin of the coal field. One of the localities 

 has already been mentioned incidentally while describing the car- 

 boniferous limestone of Portage River. At that place the coal 

 measures lean in steeply inclined position against the slope of 

 a hill, capped with the carboniferous limestone. East from the 

 limestone quarries the shales of the coal measures inclose thick 

 beds of plastic fire-clay, full of the stems of Stigmaria, and abound- 

 ing in kidney-ore concretions. The Jackson Pottery draws large 

 quantities of its clay from these diggings. The owner of the clay 

 pits informs me that he bored with an auger through 50 or 60 

 feet of soft shale and clay, and found no hard rock bed to resist 

 its progress. 



In Spring Arbor township is another coal mine on Sandstone 

 Creek, which, like the before-mentioned one, two miles further 

 north, in the bed of the same creek, has only shales for a roof ; it 

 was worked, however, at the time of my visit. Its coal seam is 3 

 feet thick, and resembles the coal of the Jackson mines. The shales 

 incumbent ^on the coal are about 30 feet thick. They contain 

 numerous geodes of kidney ore and stems of Stigmaria transform- 

 ed into iron pyrites. Below the coal, for a number of feet, shales 

 continue, and then a heavy sand rock follows. Not many steps 

 from the mine a well was drilled to the depth of 65 feet ; its lower 

 part went through sand rock altogether, and at the depth mentioned 

 a copious stream of good, drinkable water was struck, which rose 

 to the surface, and has since continued to flow freely. 



North of Albion, the quarry of Mr. Fisk is indicated in Winchell's 

 geological report for 1861 as a typical exposure of his Parma 

 sandstone. The sandstone is a whitish, coarse-grained, partly con- 

 glomeratic, soft rock, similar to some layers of the sandstones of 

 Jackson. Mr. Geiger, a well-borer, living in the immediate vicinity 

 of the place, informs me that he bored-through 19 feet of the sand 

 rock, and struck a bed of good coal, 3 feet in thickness, underlying 

 which were other sandstones. This coa:l seam would be unusual if 

 the incumbent rock has really the position Mr. Winchell gives it ; 

 but from my own observations in the surrounding country, I am 

 inclined to take the sand rock as the equivalent of Mr. Winchell's 

 Woodville sandstone. 



North of Jackson County, in Eaton and Ingham counties, the 

 presence of seams of coal has been ascertained through artesian 

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