352 A, Winchell on the Rocks of Michigan, 
ArT. XXX V.—WNotice of the Rocks lying between the Carboniferous 
Limestone of the Lower Peninsula of Michigan and the limesiones 
of the Hamilton Group: with descriptions of some C opods 
supposed to be new to science; by ALEXANDER WINCHELL, State 
Geologist of Michigan. . 
THRovuGHOUT the counties of Hillsdale and Calhoun, and the 
southern half of Jackson county, in the Lower Peninsula of 
Michigan, occur frequent outcrops of a fine, friable ferruginous 
sandstone whose stratigraphical position in this part of the state, 
is not more than forty or fifty feet below the Carboniferous lime- 
stone. The whole thickness of the series is less than 300 feet. 
lowest strata here are bluish, shaly and highly micaceous. Th 
most instructive exposures of this part of the sandstone series 
iferous beds the “Napoleon Group,” though it will appear vs 
two eens. 
From this part of the state, the outcrops of these two ie 
d 
To- 
ce 
PN ead 
