Notes upon the Geology of the Western States. 53 



part resting upon what has been very appropriately termed the 

 Chemung group. This latter object was the one first taken up, 

 and the junction of the two formations traced with as much care 

 through Ohio as it has been in Pennsylvania and New York. 

 Again, after the reappearance of the carboniferous group in In- 

 diana, the same line of observation was tal^en up and followed to 

 the Mississippi river. Throughout the whole of this great ex- 

 tent, the fundamental rock of the system maintains its position 

 and essential characters in a remarkable degree. The coarse 

 gray or drab sandstone and conglomerate of southern New York 

 and Pennsylvania, is perfectly represented throughout the coal 

 region of the west. 



It may not be improper to state here, that the great coal basin 

 of Pennsylvania and Ohio terminates to the east of the centre of 

 the latter state, following a general S. W. and N. E. direction. 

 Nearly along the boundary line between Ohio and Indiana, and 

 in the same general direction, there is an anticlinal axis, throwing 

 off the strata in opposite directions, and if ever the upper masses 

 existed, elevating them so much that they have been swept off. 

 Near the centre of Indiana the carboniferous rocks again appear, 

 occupying the southwestern part of that state and a large portion 

 of Illinois, extending in a narrow belt across the Mississippi river. 

 The coal of Kentucky and Tennessee may be considered a part 

 of the same basin, separated only by the Ohio river. The coal 

 basin of Missouri is entirely distinct, being separated by the ele- 

 vation of the lower rocks ; the same may be said of the Michi- 

 gan coal basin, which is separated from that of Indiana and Illi- 

 nois, by an axis running more nearly in an east and west direction. 



In tracing the rocks of this great western region, the carbon- 

 iferous group forms a good starting point, and having no hypo- 

 gene rocks, nor even the lower members of the transition or Silu- 

 rean system, except at a few distant points, this becomes of the 

 greatest importance. The conglomerate, sometimes a coarse 

 grey sandstone with lines of cross stratification, is the most prom- 

 inent member of the series, and the one which can best be traced 

 over a great extent of country. On the Cuyahoga river in Ohio, 

 it is seen to great advantage at the falls and other places, having 

 a thickness of about one hundred feet : from this place it extends 

 S. W. towards the Ohio river, and is visible in abrupt cliffs in 

 many of the southern counties. In Indiana and Illinois it is 



