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Austin, Texas, March 31, 1890.

Mr. E. T. Dumble, State Geologist.

DEAR SIR—

Having received instructions to make as detailed a section as the time would permit of the southern part of the Carboniferous formation in Central Texas, I took the field at Lampasas on March 13, with Mr. C. C. McCulloch, Jr., as assistant. The general route was west to the Colorado, then south to the contact of the Carboniferous and Silurian near Cherokee Creek, San Saba County. From that point we traveled north and west to the town of San Saba, and thence, via Richland Springs, Milburn, Trickham, and Waldrip, to Santa Anna. We then turned southwest to Brady, Camp San Saba (McCulloch County), reaching San Angelo May 31. In making the examination the greatest care was taken in the exact identification of strata. Where there was a stratum which could be recognized with certainty, it was traced from hill to hill until its exact relationship to the over and underlying beds was determined. This was prevented by the drift in many places, and therefore a continuous section could not be secured. Wherever an exposure of sufficient extent was found, instrumental measurements were made of dip, etc.

Having completed this, I received instructions to continue westward and make a like investigation of the Permian area. I therefore, with my party, began the work of exploring the Permian formation at its extreme southern limit, which is a few miles south of San Angelo, in Tom Green County. The boundary of the formation had not been definitely determined except at places widely distant from each other along the eastern edge. I therefore undertook to trace the eastern boundary of the beds, or the line of contact between the Coal Measures and the Permian. I traveled down the main Concho River to a point almost south of Ballinger and a few miles above the confluence of the Concho and Colorado rivers. I then went to Ballinger, in Runnels County, and thence by way of Buffalo Gap to Baird. Finding at Baird that I was east of the contact between the two formations, which had been obscured by the overlying Cretaceous to the south, I turned westward to Abilene, in Taylor County.

The line of contact between the Carboniferous and Permian is seven or eight miles east of Abilene. At Abilene I was joined by the State Geologist, who accompanied the party to the Double Mountains. From Abilene we turned northward to the Clear Fork of the Brazos River; we then went down the river northeastward, being all of the time on the beds of the Permian; and passing through old Fort Phantom Hill, we reached the road from