Texas Palwozoic.— Tarr. 169 
THE CRETACEOUS COVERING OF THE TEXAS 
PALAOZOIC.* 
Ravpu 8. Tarr, Cambridge, Mass. 
The question as to whether the central Paleozoic and pre- 
Paleozoic region of Texas was completely covered by the Cre- 
taceous, is still a mooted question. Prof. R. T. Hill has at 
various times stated that this was the case, giving numerous rea- 
sons for the statement; but Dr. T. B. Comstock, who, by his de- 
tailed study of the central mineral region of Texas, is well quali- 
fied to speak upon the subject from other points of view, has 
come to the opposite conclusion. In the second annual report 
of the Texas geological survey he has again stated this conclu- 
sion, giving therefor numerous reasons of considerable value, 
A study of the region immediately north of this area has con- 
vinced me of the accuracy of Prof. Hill's conclusion, and it is 
my purpose at this time to place the reasons for this conclusion 
on record, 
The beginning of the Carboniferous epoch found the central 
region of ‘Texas a land area considerably denuded. This is 
proved by the bays and promontories now being uncovered by the 
erosionof the overlying Carboniferous. It was probably a mount- 
vinous area, a part of a much more extensive system now buried 
beneath later deposits. More than 8,000 feet of Carboniferous 
rocks were laid down and the sediments forming these rocks came 
in large measure from the central region or from its extension 
now buried. This is proved by the conglomerate pebbles in the 
Carboniferous. In later Carboniferous times, during the deposi- 
tion of the Coleman beds, the Carboniferous of earlier date had 
been added as a coastal strip to the older land. The general ab- 
sence of conglomerate and sandstone in these rocks is proof of 
this, and the presence of numerous shore lines in the Coleman 
beds points to the same conclusion. The extensive Permian rocks 
of central western Texas are in the main inland sea deposits, and 
during this time the Paleozoic was still land. From the close of 
the Permian to the beginning of the Cretaceous we have no det- 
inite evidence from the Texas deposits, so far as they have been 
studied, though there can be little doubt that the older Paleozoic 
rocks remained dry land. 
Thus, from the beginning of Carboniferous times, and earlier, 
*Published by permission of Mr. E. T. Dumble, State Geologist of Texas. 
