Texas Palwozoic.—Tarr. We" g 
expressing itself. In this way the correspondence of present and 
ancient valleys may be accounted for even though the entire re- 
gion was once completely buried beneath Cretaceous strata. 
The eighth and last argument is in no essential particular differ- 
ent from the first, and therefore requires no separate answer. 
With the exception of two of Dr. Comstock’s arguments, other 
explanations seem possible,and these explanations do not militate 
against the theory that the entire Paleozoic and older rocks were 
once buried beneath the Cretaceous. The weight of the other two 
arguments I cannot attempt to decide upon. 
Granting that the Cretaceous at one time extended completely 
across the Paleeozoic and Archean, it remains to be shown how it 
happens that this area contains now no relicof this former covering, 
whereas the Carboniferous abounds in such evidence. The rea- 
son for this cannot be stated definitely, although there are several 
possible explanations. In the first place the Cretaceous, owing 
to the elevated nature of the Paleozoic core, may have been 
actually thinner here than elsewhere, and hence more quickly cut 
through. Another possible explanation is that the post-Cretaceous 
deformations noted by Dr. Comstock may have elevated these re- 
gions above sea level earlier than the neighboring regions, and 
thus given them a long start in the race of denudation. A more 
reasonable explanation than these even exists in the probable form 
of the Cretaceous sea floor. The central highland region of 
Texas, is at present much more elevated than the uppermost Cre- 
taceous beds to the southeast. Even the accumulation of several 
thousand feet of sediment could hardly be expected to completely 
efface this old mountain area. It most probably formed a oreat 
dune in the Cretaceous sea, which, in post-Cretaceous times was 
the first to be raised above the sea, and consequently the first to 
be attacked by erosive agents. That the elevation of the Cre- 
taceous was in great measure continental in character is shown by 
the uniformity in dip throughout the Cretaceous area. It seems 
probable, therefore, that if, as is supposed, the central district 
was submerged and covered, it was the first to appear, and this 
fact will account for the quite complete removal of Cretaceous, 
and the adjusted courses of the streams. 
In summary it may be said that it has been the attempt of this 
paper to prove that the central Palaeozoic and pre-Paleozoic core 
of Texas has been from before the beginning of Carboniferous to 
