682 TRANS-PECOS TEXAS. 



red sandstone and quartz grains imbedded in a red sandy matrix. It is dis- 

 tinctly stratified, tilted only near the serpentinous and other intrusions. Its 

 grain diminishes in size in the different layers, changing deeper down into a 

 fine-grained dark brick-red sandstone, which only now and then faintly shows 

 stratification, and weathers into globular bowlders. This red sandstone, judg- 

 ing from the float, also appears on a western slope of the Van Horn Moun- 

 tains in the valley south of Haskell, and may contain opals. The grit in its 

 most southern exposure in the Carrizo Mountains occurs in the Round Moun- 

 tain at Allamore, rising above the flat and the low Carboniferous limestone 

 hills that run parallel with the Texas and Pacific Railway to about one mile 

 west of Allamore. 



On the east side of this gritty butte the red schistose rocks disappear under 

 the grit strata, reappearing occasionally in the more northern part of the Car- 

 rizo Mountains, together with serpentinous, basaltic, and greenstone intru- 

 sions; and it does not seem at all improbable that they are the excessively 

 metamorphosed fine-grained sandstones on which the grit rests unconform- 

 ably, and which, arranged in wavelike hills, covers the basins between the 

 cliffy (shore) lines of the Sierra Diabolo range, the Carboniferous limestone 

 cliffs of the northern part of the Carrizo Mountains, the metamorphic cherty 

 limestone elevations north of Allamore, and those forming the western dam 

 of this basin. The same red sandstone extends along the foot of the south- 

 ern cliffs of the Sierra Diabolo and reappears again under the group of brec- 

 ciatic conglomerate hills northwest of the carbonic limestone cliffs near Eagle 

 Flat, which cliffs rest partly on micaceous schistose rocks similar if not iden- 

 tical with those of the Carrizo Mountains, partly on a reddish granitoid rock. 

 Both the schist and granitoid rock are traversed by white and by ferruginous 

 quartz dykes with nearly east-west strike. The western outrunners of the 

 Diabolo red sandstone hills parallel to the Diabolo cliffs undergo a gradual 

 change into a brownish quartzitic sandstone. South of these hills, seemingly 

 resting on them and parallel with them, we find ridges of strongly metamor- 

 phosed cherty limestones, with ferruginous quartz layers and siliceous iron 

 veins containing up to forty-six per cent of iron, and two to four ounces of 

 silver, and traces of gold. 



These cherty limestones extend between the Carboniferous cliffs west of 

 the Eagle Flat and the cliffs of the Sierra Diabolo, sloping down to the large 

 basin east of Sierra Blanca. They are traversed by and partly resting on the 

 slopes of a group of brecciatic conglomerate hills with igneous intrusions. In 

 some places of these conglomerate hills appears the red sandstone of the Dia- 

 bolo, but here it is distinctly stratified in finer and coarser gritty layers, and 

 it shows ripple marks occasionally, and the different weathering seems to in- 

 dicate a lesser degree of metamorphosis. These sands are non-fossiliferous, 



