Record of Geology of Texas, 1887-1896. 
249 
Tarr, Ralph S. 
The cha.raeter and scqpe of this paper are shown in its opening and 
closing paragraphs : 
“The question as to whether the central Paleozoic and Pre-Paleozoic 
^ region of Texas was completely covered by the Cretaceous, is still a mooted 
question. Prof. ,K. T. Hill has, at various times, stated that this was the 
case, giving numerous reasons for the statement; but Dr. T. B. Comstock, 
who, by his detailed study of the central mineral region of Texas, is well 
qualified 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 conclusion, giving therefor 
numerous reasons of considerable value. 
“A study of the region immediately north of this area has convinced me 
of the accuracy of Prof. HilPs conclusion, and it is my purpose at this 
time to place the reasons for this conclusion on record.” P. 169. 
“In summary it may be said that it has been the attempt of this paper 
to prove that the central Paleozoic and Pre-Paleozoic core of Texas has 
been from before the beginning of Carboniferous to Cretaceous times, 
almost, if not quite uninterruiptedly, a land area subjected to denudation; 
that, at the beginning of Carboniferous times, the land was already 
eroded beyond the stages of youth nearly to topographic maturity; that; 
when the Crebaceous period began, it found the Carboniferous area a low- 
lying, base-leveled area, a peneplain skirting a moderately low and not 
strikingly diversified highland of older and harder rocks; and that the 
Cretaceous ocean completely covered this region, depositing thereon a 
considerable thickness of Cretaceous rocks. The encroachment of the Cre- 
taceous sea was rapid, as is indicated by the peculiar Trinity conglome- 
rate, which is apparently hurriedly worked over land debris. The final 
chapter in the history was the Post-Cretaceous elevation, which first raised 
this region above the sea, because its former elevation was in part indi- 
cated in the topography of the Cretaceous ocean even through the blanket 
of Cretaceous strata which covered it. Being the first to be raised above 
the sea, it was the first to be eroded, and consequently now, over large 
areas, shows no signs of the former covering, either in remnants, Quater- 
nary debris, or in unadjusted stream courses.” P. 178. 
S99. 
A Hint with respect to the Origin of Terraces in .Glacrated 
Regions. 
Amer. Jour, of Science, III, Yol. XLIV, pp. 59-61. Hew 
Haven, July, 1892. 
Doubt as to the exact method of formation of terraces in rivers flooded 
by the melting of the ice sheet, as, for instance, the Connecticut. Some 
suppose that terraces mark recent erosion in a drift- filled valley; others, 
that they mark the high stages of floods. The object of this paper is “to 
record some observations in an entirely different region where the terraces 
of glaciated regions are being imitated, and where the general conditions 
are quite similar to those attending the formation of the terraces in 
