The exploration upon which this report is based extended over parts of Lampasas, San Saba, Coleman, McCulloch, Concho, and Tom Green counties. The object of the trip was to secure such general information regarding the section as would indicate the special lines of work that could be most advantageously pursued in the detailed survey of this region.

During the present expedition strata belonging to the Silurian, Carboniferous, Cretaceous, and Recent systems have been observed, some of which will be more fully mentioned under separate headings, but their boundaries must be left for more detailed work.

The different formations have been identified either by their fossils or by their relative positions in regard to other known strata. There is great uniformity of structure in the individual strata of the several formations over the entire field; so much so that one becoming familiar with the characteristics of a stratum in one place need have little trouble in recognizing it elsewhere when found.

The strata of the Paleozoic Group as observed along the route have a general and uniform dip to the north and northwest, with little or no disturbance, except in one or two instances which are noted. The Mesozoic strata, on the contrary, have a general inclination to the southeast.

Few evidences of faults or folds of the strata in any of the formations were seen, except where they are in contact with the eruptive rocks. The alternations of limestone, sandstone, and shales in the various formations show that the periods of their deposition were attended with alternating conditions of subsidence and elevation.

The rocks of the Crretaceous system are found in contact with strata of both the Carboniferous and Silurian, showing that the Silurian and Carboniferous