331 



The following general section, will exhibit the order of puccsssion 

 and approximate thickness of the rocks above described, lying below 

 the coal basin, and is a continuation of the table given on page 326, of 

 the successive rock formations of the settled portions of our Peninsula: 



General Section^ applicable to all the rocks below the coal beds of 

 Michigan, in that portion of the Peninsula included in this r^ 

 port. 



D. 



Sandstones of 

 Jackson, Cal- 

 houn and 

 Hillsdale. 



( Coarse quartzose, grajish sandrocks,. . 



Fine gi'ained, ash colored and dingy 

 green, interstratified with slaty sand- 

 stone and clay shales, 



Yellow sandrocks, colored by iron, and 

 abounding in fossils, 



Meaii 

 hickness 



SOOfeet. 



E. Dark gray and blu« in<luiated clay, containing kidney 

 (Counties of Hillf^dale, Branch and Calhoun, . 



iron. 



46 



Coai'se sandstone, or pailial congio?nerate, 



Yellow and greenish sandstones. (Coast of Lake Huron, 

 at Point aux Barques,) 



250 



a 



Slaty, argillaceous sandstone, alteniating with sandstone 

 and clay slates, 



Blue clay slates and flays, with alternating gypsum beds 

 and gypseous marls. (Lake Huron coast, below Point 

 aux Barques, 



180 



H. 



Soft, coarse grained santlstones, (occupies bed of Lake 

 Huron, at its foot,) exceeds 



230 



I. 



Black alluminous slate, containing pyrites. (Coast of Lake 

 Huron, at Thunder Bav,) 



K. Cray liraerock, fossils abundant. 

 Erie, 



(West end of Lake 



The rocks in the above section embrace all those which are included 

 in the divisions marked D, E, F, G, H, I, and K, in the Geological Sec- 

 tion prefixed to this report. 



DIP OF THE ROCKS. 



Great irregularities of dip are observable in all of our rocka, which cir- 

 cumstance has increased the difficulty of determining the precise rela- 

 tire position, extent and thickness of the several strata. Many of the 

 sandstones belonging to, and immediately undei'lying the coal, are much 

 shattered, as if by a quick vibratory motion, and a similar cause has oc- 

 casioned contortions of dip. in most of the still older rocks I have, 

 therefore, refrained from noting the amount and direction of dip at the 

 various localities mentioned. All the rocks on the eastern slope of the 



