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. 
TERRANE PERCENTAGES OF COAL PRODUCTION. 
FORMATIONS. 
03 
£ 
£ 
Missouri 
Kansas 
Ark. 
Ind. Ter. 
< 
MISSOURIAN series: 
Atchison shales 
0.2 
Platte shales 
6.0 
0.3 
1.2 
Lawrence shales 
Parkville shales 
Thayer shales 
0.2 
0.8 
0.2 
92.5 
DES MOINES SERIES: 
Marais des Cygnes shales. . . .... 
Henrietta formation 
1.0 
15.4 
83.4 
0.1 
18.5 
81 4 
0.4 
7.0 
91.4 
Cherokee shales 
90.0 
10.0 
100.0 
ARKANSAS SERIES 
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 will 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 
