Serial J^omeiiclnfnre of thv. < 'arhoniferoaa. — KeyCfS. 2S 
they may be so called, have been very general and very inde- 
finite. In no way are any of them to be exactly parelleled 
with those of adjoining localities. Moreover they are per- 
fectly arbitrary, with little or no attempt to delimit the foc- 
raations either on natural, stratigraphical or fannal grounds. 
Of late, detailed investigations by different individuals have 
been going on over a large portion of the region, first in Iowa, 
then in Missouri and finally in Kansas, with some reconnais- 
sance work in Nebraska, Indian Territory and Arkansas. A 
sufficient number of facts have now accumulated to indicate 
plainly the positions of the lines of demarkation between the 
principal larger divisions. These have been found to be well 
defined over the whole basin. Smaller subdivisions, which are 
of only local consequence and which differ widely in different 
localities, may be established later. Local members have been 
already named for the greater part of Kansas. Progress in 
the same direction has been made in Missouri and Iowa, 
thr)ugh the naming of the minor subdivisions has been 
deferred until a careful comparison in all the various aspects 
can be undertaken. The subdivisions of the Carboniferous 
lierc^tofore usually recognized in the AVestern Interior basin 
are : 
1. Permian. 
2. Permo-Carbouiforous. 
.3. Upper Coal Measures. 
4. Middle Coal Measures. 
5. Lower Coal Measures. 
6. Lower Carboniferovis. 
The Carboniferous rocks of the world are commonly re- 
ferred to one of three great classes: the Lower Carboniferous 
(Sub-Carboniferous), Carboniferous proper (Coal Measures), 
and the Permian. In the Mississippi basin only the first two 
of these have heretofore been considered as well marked divi- 
sions. The third and upi»ermost has claims to recognition 
west of the Missouri river, but it is doubtful whether in any 
of the region east of that stream this member exists. Al- 
thougii so importiiiit a format in!i in iiumy parts of Europe, 
where all members of the Carl)oniferous were first studied and 
defined, the so-called Permian of the Mississippi province 
does not assume sue!) great ini|)(irtaiici' as a distinct geologi- 
cal division. \n tiie region under consideration the beds re- 
ferred to it occur in Oklahoma, Kansas and Nebraska. 
