Record of Geology op Texas, ISS^-lSOe. 
79 
Drake, N. F. 
the edges of these outeropiping beds, and has flat tops of greater or less 
'extent, according to the amount of the capping material of the harder 
horizons. » 
“The Carboniferous, composed of beds dipping to the west and north- 
west, has a topography characterized by parallel ridge-like undulations 
which extend northeast and southwest, or more exactly N. 20° to 30° E,, 
and S. 20° to 30° W- These ridges slope so gently on the west side that 
they may be more properly called escarpments or benehes. The bench 
or the escarpment faces east, while the slope of the surface to the west and 
northwest is slightly less than the dip of the underlying strata, and in 
the same direction. The lowest level reached on the northwest side of 
these ridges or benches does not quite extend down to that on the southeast 
side, so that going northwest, each ridge or escarpment gone over places 
one at a slightly higher elevation than the preceding one, thus making 
the average slope of the country to the east and southeast, while most of 
the surface slope is to the northwest. This character of topography exists 
because of the dip of the beds N. 60° to 70° W., and because of the different 
degrees of hardness of the beds. The softer beds rapidly erode and are 
carried away, leaving the harder beds projecting at the top of the escarp- 
ments, and forming the surface rock to the west and northwest, nearly to 
the base of the next escarpment of overlying beds. 
“The whole of this area was once covered by Cretaceous strata, which 
rested unconformably on Carboniferous, the former dipping very slightly 
to the southeast and the latter dipping 25 to 300 feet per mile to the 
northwests Most of this Cretaceous cap has been carried away by erosion, 
leaving the underlying Carboniferous beds exposed. 
“Unequal erosion over this area has left the Cretaceous with an irregu- 
lar border, and in isolated areas; or the Cretaceous areas in this fleld are 
now as follows: In isolated buttes, such as Santa Anna Mountain, Bead 
Mountain, iBobinson Peak, etc., in areas of considerable extent, as that 
south of Brown wood and that north of Talpa; and others in ridges or 
spurs, like the Brady mountains, running out from the main Cretaceous 
area. 
“The Carboniferous beds of. this fleld comprise the southern extension 
of the central Carboniferous area, which extends from a little south of the 
Colorado river in San Saba county northward nearly to the Bed river in 
Montague county. This Colorado river coal field is almost cut off from 
the main body of the Coal Measures to the north by the overlying neck- 
like extension of the Lower Cretaceous beds stretching from the west 
corner of Comanche county across the southwest corner of Eastland and 
the southern part of Callahan, into (Runnels county.” Pp. 3i57-359. 
111. Dumble, Edwin T. 
The Nacogdoclies Oil Field. 
Geol. and Scientific Bnll., Vol. I. 'Houston, July, 1888. 
“The existence of oil in these eastern counties has been an acknowledged 
fact for many years, and numerous attempts have been made to obtain 
it in paying quantities, none of which proved at all successful until lately. 
About two years ago several parties concluded that they would investigate 
