128 IOWA ACADEMY OF SCIENCES 



drainage in no way dependent upon the Carboniferous 

 drainage. Where the great uplift of Missouri and Arkan- 

 sas over the northern part embraced by the so-called Ozark 

 isle and the southern part composing the Ouachita moun- 

 tains were made up of resistant limestones, these yielded 

 less quickly to erosion than the central soft shales, and the 

 Arkansas river which happened in the old peiieplain to 

 traverse the central part of the uplifted area was able to 

 cut its way down as fast as the region rose and was thus 

 able to maintain its old course. The present uplift, which 

 is due to one general movement, is now apparently divided 

 into two elevated regions separated by a low valley. 



NAMES OF COALS WEST OF THE MISSISSIPPI 

 RIVER. 



BY CHARLES R. KEYES. 



The coals of commerce acquire names by which they are 

 widely known, and upon which their reputations stand. 

 These names are not geological titles; and coal samples 

 having the same name may, and usually do, come from 

 different mines and even from different horizons. Many 

 analyses and physical tests are made for various industrial 

 purposes from samples taken from the railroad cars, after 

 the latter have reached their destinations. 



In the American coal fields, east of the Mississippi river, 

 some coals noted for particular qualities are widely known 

 by special designations. The names have a peculiar value 

 in purely scientific work because the seams are of great 

 areal extent. The geological positions of such coals are 

 inferred as soon as the names are mentioned. 



In the Western Interior coal field, numerous names of 

 coals are widely known to the trade; but on account of the 

 rather limited lateral extent of most of the seams their 

 geological horizons cannot be easily inferred. In the fol- 

 lowing pages is given a list of all of the important coals 



