126 LOWER PENINSULA. 



Drift 6 ft. 



Sandstone 27 " 



Conglomeratic sandstone 2 " 



Bituminous shale Sin. 



Small coal seam. 



Soft black shale 2 " 



Black shale with kidney ore 19 " 



Bituminous coal i " 



Fire-clay 8 " 



Fine-grained sandstone 3 " 



Black shale i "6 '' 



Fire-clay 7 " 



Sandstone and shale alternating 40 " 



The shaft of the Woodville mine, 3 miles west of Jackson, inter- 

 sects. 



Drift 12 ft. 



Sandstone 30 " 



Dark shale 43 " 



Coal 4 " 



Shales 3 " 



This mine is now abandoned. 



We see, by a comparison of these sections, many minor differ- 

 ences in the sequence and thicknesses of the strata, but a general 

 conformity conspicuous throughout. The highest position is al- 

 ways taken by a light-colored, coarse-grained sand rock of from 25 

 to 30 feet in thickness ; below it, invariably, shales or alternations of 

 sandy fire-clays with shales are found, in a maximum thickness of 40 

 feet, but usually in much thinner beds. Next a bed of coal be- 

 tween 3 and 4 feet in thickness follows in almost every one of the 

 localities, and under it are arenaceous shales or sand rock. In the 

 exposures at Jackson, the upper sandstone is frequently found 

 in thick, tolerably compact beds, which are useful in supplying 

 building-stones ; other beds are thinly laminated, of irregular, 

 discordant stratification, often soft and friable between the fingers. 

 Between the harder solid ledges conglomeratic seams are fre- 

 quently wedged in, or kidney ore and pyritous masses are dis- 

 seminated ; locally the ledges are colored a dark chocolate 

 brown by a ferruginous cement uniting the quartz granules. Oc- 



