IOWA ACADEMY OF SCIENCES. 



131 



some extent, though in several the amount is so small that 

 it may be neglected altogether, for it is no greater than is 

 found in almost every geological formation. None of the 

 last named have any claim to the title of coal-bearing 

 strata. 



One important feature which has been clearly brought 

 out by the recent investigation is the fact that the great 

 workable coal bodies of the Trans-Mississippian region are 

 definitely limited in their stratagraphic extent. By this 

 great restriction in geological range of the coals as com- 

 pared with that formerly supposed, the figures for the 

 actual available tonnage are, perhaps, not so much affected 

 as are the figures for the areal extent of the district that 

 can now be regarded as a possible producing field. 



To present the proposition more clearly, we may tabulate 

 the coal production of the entire region according to the 

 percentages, in each state, that each geological formation, 

 or terrane, supplies. 



It appears somewhat startling that from the Cherokee 

 division alone should come nine-tenths of the total coal 

 output. Yet this is about the proportion that it will con- 

 tinue to supply in the future. If anything, the Cherokee 

 percentage wall increase, rather than diminish, as the Hen- 

 rietta coals come from a single seam. At least, there 

 appears to be only one seam in a locality belonging to the 



