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In the section made by the writer during the winter of 1888-89, across the Central Texas Carboniferous area of the Colorado Valley the section ended a few miles northwest of Coleman, where the Carboniferous is covered by Cretaceous. The Carboniferous is there dipping gently northwest while the Cretaceous lies uncomformably with a very gentle southeast dip. The Carboniferous beds at the point where they are covered by the Cretaceous, belong to the Coleman division and consist of mottled and vari-colored clays interbedded with limestones containing considerable clay. A description of these beds appeared in the First Annual Report.

ROUTE FOLLOWED.—From the point where the last section ended I travelled northwest to Abilene and thence W. S. W. along the line of the Texas&Pacific R. R. to the Pecos river, a distance of 279 miles. With the exception of certain small Cretaceous areas and some beds of Carboniferous between Coleman and Abilene, the strata along this route are all Permian.

The first of these Cretaceous areas was seen northwest of Coleman where it forms a divide between the head-waters of the south branches of Jim Ned creek and some small creeks directly tributary to the Colorado river. It is a very much degraded area consisting chiefly of beds of the Trinity division capped in the higher parts by limestones of the Comanche series. On the southeast side the base of the Cretaceous is 1930 feet above sea level but three miles northwest the contact between the Cretaceous and the Carboniferous is found at an elevation of 2025 feet.

Cedar Gap is a pass in the range of Cretaceous buttes formed by the combined erosion of two creeks, one tributary to the Colorado and the other to the Brazos. A range of these Cretaceous buttes or mesas extends from near the Colorado eastward, several miles beyond Cedar Gap and mark the divide between that river and the Brazos, and are remnants of the old Cretaceous plateau remaining in degraded form in the region of slow erosion, or at the head-waters.

Above the general level of the gap, in the lowest part of the butte are about twenty-five feet of red beds, evidently Permian. Above this are one hundred feet of Trinity Sands capped by twenty-five feet of thick bedded limestone (Comanche series). The lower Trinity beds are yellow and gray sands and clays with a considerable admixture of red clay. This red clay is so abundant as to give the lower part of the buttes