66 A GEOLOGICAX SUEVZT OF LANDS 



black shale which is exposed in the south bauk of Sycamore creek 

 in block 2 and farther down in this stream, contain from four to 

 nine per cent, of their weight of bituminous material. About two 

 and one half mile north of Comstock, several feet of bituminous 

 shale have been found in a well, and some of the pieces taken out 

 contain nearly fifteen per cent, of bitumen. This is sufBcient to 

 support a flame when the shale is thrown in fire, and this shale as 

 well as the darkest shale on Sycamore creek is sometimes locally 

 spoken of as coal. When burned, even the best I found, leaves a 

 residue of no less than eighty-five per cent of ashes. Oil which is 

 reported to have been found in some well near Johnston siding 

 evidently comes from this horizon. In a well made by Mr. Lester- 

 jette near the northwest corner on survey 1 in block 9 at the west 

 end of Anacacho mountain, these dark shales were penetrated at 

 a depth of 810 feet. The samples taken at the time are still 

 preserved and are found to be slightly bituminous. The drillers 

 likewise reported a show of oil in the well at this depth. 



The basal part of the Eagle Ford beds almost always contain 

 a small amount of bitumen. In the calcareous ledges there is 

 enough to cause the rock to emit an oily odor when it is thor- 

 oughly crushed. This is true for the entire state of Texas and 

 beyond, north as well as south. But the formation has a com- 

 pact texture. It is a rock with little porous space, and it can not 

 be expected to yield any considerable flow of oil or gas. The 

 small quantities of oil which have been discovered from these 

 shales are heavy paraffine oils of high value as lubricators. 

 Should any highly charged black shales be found, they might 

 perhaps be profitably distilled for such oil. 



THE AUSTIN CHALK. 



The Austin chalk is named from the city of Austin, where it is 

 frequently exposed in the streets east of Shoal creek. With the 

 other formations already described it extends as a continuous 

 belt almost across the state. It consists of white soft limestone, 

 usually in ledges varying from six inches to two, or at times 

 several feet in thickness. The rock is more indurated and stony 

 than true chalk, but it consists of the same material, being 

 composed of foraminiferal ooze. In its lower part there is a zone 

 of heavy beds, which furnishes good building stone. This is 



