PALEONTOLOGICAL GEOLOGY 
267 
and Carlile faunas, or between the Carlile and the Greenhorn 
faunas, or even between faunas of some of the zones in the Car¬ 
lile formation alone. And yet these faunal changes within the 
later Cretacic succession were certainly not caused Ly the complete 
retreat and a succeeding advance of the sea. The restricted distri¬ 
bution of the Woodbine sand and its absence from central and 
southern Texas suggest an unconformity at the base of that forma¬ 
tion, or at the bottom of the Eagle Ford horizon,^ but all recent 
workers consider it unimportant if present. Stephens ® has pre¬ 
sented evidence in favor of an erosion interval between the Eagle 
Ford beds and the Austin chalk, a suggestion which is also sup¬ 
ported by the varying thickness of the former. It is probable, 
however, that all of these unconformities, so far as they actually 
exist, represent only local and temporary uplifts the influence of 
which was not felt over very wide areas. 
The proposal to elevate the Comanche succession to the rank 
of a system under the name Comanchean, which was made in 
Chamberlin and Salisbury’s Geology in 1906, has never seemed 
to mie to be justified by the facts known at that time, and the argu¬ 
ments then advanced for it has been tremendously weakened by all 
subsequent investigations. Both the physical break and the faunal 
change at the top of the Comanche section now seem much less 
important. In arguing for the importance of the division it was 
assumed that the Comanche section has approximately the same 
upper limit as the European Lower Cretaceous, that is, the base 
of the Cenomanian; but many European paleontologists have long 
referred the Washita beds to the Cenomanian, and of late the 
paleobotanists have become insistent on the correlation on ac¬ 
count of the character of the flora of the Cheyenne sandstone. 
I have often stated ^ in print that the Washita beds may be in 
part, at least, Cenomanian, when explaining that “the whole of 
the Comanche Series is treated as Lower Cretaceous, because, in 
the Texan area, the top of the Comanche section is the only 
natural and satisfactory major plane of division in the Cretaceous.” 
Some of those who accept the correlation of the Washita forma¬ 
tion with the Cenomanian, and wish to recognize two systems 
within the general Cretacic succession have tried to harmonize 
2 Bulletin of University of Texas, No. 44, p, 72, 1916. 
3 Prof. Paper, U. S. Geol. Survey, No. 120, p. 148, 1918. 
4 See for example: Journal of Geology, Vol. V, pp. 583 and 656; also idem., 
Vol. XVII, p. 416, 1909; also. Mo. U. S. Geol. Surv., Mo. XPIV, p. 14, 1903. 
