Geographic Features of the Texas Region. — Hill. 79 
5. Depressions pro- 
duced by Den\ided 
Anticlinals. The 
Central Denuded 
Region. 
(a) The Upper 
Cross Timbers. 
(b) The Older Rock 
-(Paleozoic) Areas. 
b' The Palo Pinto 
or Coal Measure 
Area. 
b" The San Saba, 
or Granite Area. 
(c) The Red Beds. 
c' The Abilene 
country. 
c" The Gypsum I 
country. 
750—2000. 
1000—2000. 
1000—2000. 
2000. 
2000. 
Jointed, folded and 
oiher disturbed, 
sandstones, clays, 
limestones, gran- 
ites, etc., of Pre-Cre- 
taceous age. 
The basal sands of the 
Comanche Series 
known as Pock 
Sands. 
Sandstones, lime- 
stones, clays and 
coals of upper Car- 
boniferous. 
Older limestones, 
schists, etc., with 
above and later 
granites. 
Dark red marly clays 
and sandstones. 
Light red marly clays 
and sandstones with 
much gypsum. 
Ancient disturbed 
areas, probably part 
of the Ouachita dis- 
turbauce, whicii 
have alternately 
served as the conti- 
nental divide be- 
tween the interior 
basins and the At- 
lantic. It was bnr- 
ied in Lower Creta- 
ceous time«, but was 
land in the .Jura- 
Trias and Laramie- 
Eocene epochs. 
Since the greater 
elevation of the 
western region. It 
has rapi dfy suc- 
cumbed to erosion, 
and is now a depres- 
sion iu the centre of 
the state. 
B. Plains. 
1. The Coast Prairie 
Region. 
2. The Eo-Lignitie, or 
Sandy Region. 
3. The Black Prairie 
Region. 
Subdivisions. 
(a) Main Black 
Prairie. 
(b) Chalky Divi 
sion. 
(c) Minor Black 
Prairie Division. 
(d) Lower Cross 
Timber Division. 
4. The Grand Prairie 
Region. 
5 The Staked Plains 
Region. 
0—200. 
200—500. 
500—750. 
750—2000. 
2000—4000. 
Shallow marine and 
littoral sediments of 
PortHudson epoch of 
Hilgard and Lough- 
ridge. 
Marine littoral clays, 
sands and lignites, 
of Eocene and Mi- 
oceneC'GrandGulf") 
epochs. 
Marine sediments of 
Upper Cretaceous 
(Meek and Hayden) 
section. 
Infra - littoral clays, 
( Ponderosa marls, 
Pierre etage.) 
Infra-littoral chalks. 
( Niobrara etage). 
Austin chalks. 
Infra-littoral clay. 
Benton etage. Eagle 
Ford shales. 
Littoral sands. Dako 
ta etage. 
Marine sediment, 
chalk, clays, oolite 
yellow marls and 
basal sands of Com- 
anche series. 
Surface, lacustral scd 
iments of Tertiary 
origin. Foundation, 
marine sediments of 
Mesozoic epochs. 
Latest Quaternary. 
Early Quaternary. 
Plateau Gravel 
epoch. 
Intimately connected 
with the above, its 
western margin 
probably being old- 
er, or the first por- 
tion of the plain 
made during the 
Plateau Gravel 
epoch. 
Probable remnant of a 
plain that existed 
from early Tertiary 
time to the present. 
Lignitic epoch. 
Probably a great lake 
region in the Mi- 
ocene or the Pli- 
ocene, antecedent to 
IAS, and elevated to 
its present altitude 
in Post-Tertiary 
time, probably syn- 
chronous with Zuni 
Plateau. 
