THE TEXAS ACADEMY OF SCIENCE 
THE RED SANDSTONE OF THE DIABOLO MOUN- 
TAINS, TEXAS. 
E. T. DTJMBLE, 
Houston, Texas. 
In the several reports of the Geological Survey of Texas, mention is 
made of a red sandstone which occurs in the Diabolo Mountains north of 
Allamore station on the Texas & Pacific Railway. This appears to be a 
very massive sandstone of red color with some white particles and of tol- 
erably even grain throughout. It is the rock which encloses the copper 
vein, a part of which has been known for some years as the Hazel mine. 
Prof. Streeruwitz in one of his reports on the region states that the sand- 
stone is possibly Devonian, basing the statement, as I understand it, 
entirely on the petrographic character of the rock (since no fossils have 
been found in it) and on its relation to the Carboniferous rock in the 
hills north of the mine. 
During a hurried trip to the locality some months ago, I observed a 
few further facts which seem to me to suggest a much earlier age, and I 
believe that more detailed investigation will result in the discovery of 
some very interesting geological conditions connected with this material. 
In the first Annual Report of the Survey, in my resume of the sys- 
tematic geology of the State, I called attention to certain schists and the 
marbles overlying them, which were found near Eagle Flat, and referred 
the marbles to the Texan group of Comstock’s Llano section, which was 
supposed to be the equivalent of the Algonkian of the geologists of the 
United States Survey. The character of the outcrop of these marbles is 
well shown on plate number XX Y of our Second Annual Report. 
I observed a red sandstone in connection with these beds, but its rela- 
tionship was obscured by faulting and was not made out. It appeared 
to occupy a part of the valley between the higher, mesa-like hill at Eagle 
Flat, sometimes called the Eagle Flat mountain, and the scarp of the 
Diabolo mountains to the north, and to be unconformable with the other 
beds observed. 
