122 
IOWA ACADEMY OE SCIENCES 
statement of the sections appears to present the facts 
most clearly. 
SERIES. 
IOWA 
KANSAS. 
INDIAN TERRI- 
TORY. 
ARKANSAS. 
Oklahoman .... 
Oklahoman. . 
Missourian 
Missourian. . 
Des Moines . 
(Wanting) 
Mississippian 
Missourian . . 
Des Moines. . 
(Wanting) 
Mississippian 
Poteau .... 
Des Moines 
Arkansan 
Mississippian. . . 
Cavaniol . . . 
Lower C M. 
Mississippian 
Poteau* 
Productive C. M. 
and Lower C, M, 
Mississippian. 
*Not the same as Poteau of Indian Territory. 
The thickness of the coal measures of the Mississippi 
valley is greater than anywhere else in the United States. 
If two east and west cross-sections, one on the north side 
of the Ozark dome and the other through the Arkansas 
valley, are contrasted, the Carboniferous series present 
about the following measurements: 
SERIES. 
NORTHERN 
SECTION. 
SOUTHERN 
SECTION. 
Oklahoman 
1 500 
1.500 
Missourian 
2,000 
1,500 
Des Moines,. 
500 
8,500 
Arkansan 
Wanting. 
20 000 
Mississippian 
1.000 
1 500 
From the foregoing it will be seen that the Lower Car- 
boniferous, or Mississippian series, with its minor divisions, 
is well defined in northern Arkansas. The Kaskaskia 
Figure 3. — Relations of the Mississippi valley members of Carboniferous; solid black 
represents Arkansan. 
