THE AGE OF ANTHRACOLITHIC ROCKS 715 
while others are certainly marine. Careful petrologic study will 
probably demonstrate that much of the arenaceous material is wind- 
blown sediment, more or less reworked by currents or waves as the 
regions were submerged or flooded. ‘That the sea ever covered the 
entire area from Kansas to southern Texas and New Mexico at one 
time may be questioned. If it did, the sediments contained were of 
such a nature and abundance, or the waters so concentrated as to 
preclude the free migration of a normal marine fauna throughout 
the basin. That marine conditions prevailed, at least locally, is 
demonstrated by the Whitehorse and Dozier faunas. 
In Texas normal deposits were laid down in higher horizons than 
in Oklahoma, and in Kansas there are reasons for believing that the 
light-colored sediments were laid down at an even later date than in 
Texas. These conditions are illustrated in the subjoined table, 
showing a vertical section of the Carboniferous and Permian rocks of 
the three states. 
The extent of this post-Pennsylvania basin seems to have been 
very great. It included much of Kansas (#), Western Oklahoma, 
much of western Texas, and all of New Mexico, Colorado, and Wyo- 
ming east of the Rocky Mountain axis. In area it probably aggre- 
gated 300,000 square miles. 
Together with the varied physical conditions of these three regions 
went corresponding faunal peculiarities. In the Albany division of 
the Texas rocks the Pennsylvanian elements of the fauna seemed to 
persist, while they are largely wanting in their equivalent beds, the 
Wichita division. A similar thing occurs in the clear-water beds of 
northern Oklahoma and southern Kansas, north of the Red Beds. 
Aside from this general fact it should be noted that along the region 
of the Red Beds and light sediment (litoral ?) contact, some of the 
Pennsylvanian elements of the Kansas fauna persisted much longer 
than in the same rocks to the northward. The fauna of any given 
horizon above the Elmdale formation varies very sensibly as we pass 
from the Nebraska to the Oklahoma line, both in abundance of specti- 
mens and species, and in the general aspect of the faunules as well. 
This is to be expected in the light of the intercalation of massive 
gypsum beds as low as the lower part of the Neosho member in the 
northern region. From it we would infer that the waters of the 
