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 peneplain 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 
