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REPORT OF MR. THEO. B. COMSTOCK.
A Preliminary Report on parts of the counties of Menard, Concho, Tom Green, Sutton, Schleicher, Crockett, Val Verde, Kinney, Maverick, Uvalde, Edwards, Bandera, Kerr and Gillespie.

INTRODUCTION.

The area traversed in 1891, with the exception of a small portion hastily crossed in going from Austin to San Angelo, is occupied almost wholly by strata of the Cretaceous period. The complication of structure and the variety of rock stages which characterize the Central Mineral Region, are, therefore, absent from this tract. By selecting a route less tortuous and aiming to follow out one of two well marked horizons, it would have been possible to obtain a practically uniform topography and to reach conclusions widely different from those which our observations now justify and require. The execution of the survey being left to the writer in large measure, and the reconnoissance being necessarily extended over a vast area, an attempt was made to so shape the course as to include the widest possible scope of structure and the most important features of the geologic history of the region.

There have been honest differences of opinion concerning the geologic changes which have taken place in this little known region, and it was thought desirable to obtain some authentic evidence by instrumental surveys. The writer of this report has been forced to adopt opinions not in strict accord with the conclusions of one or two workers, chiefly by reason of a most intimate study of the rock-masses of the Central Mineral Region, and by the running of instrumental lines of section through this particular area. It being necessary for the purposes of the Geological Survey to gather information concerning the mineral and other natural resources of the counties in the title of this report, it was deemed wise by the State Geologist to have this reconnoissance conducted by one who was familiar with the adjoining territory. This will explain both the attempt on the part of the writer to contribute facts upon a question not yet beyond controversy and his inability to discuss these facts from the standpoint of a specialist in paleontology. In so far as the fossils may be required to settle particular questions, the conclusions must here be held in abeyance, except where they may be properly used to correlate beds not widely separated geographically.

The final results of this survey must be left in a great degree for a future publication; for although the topographic data have been carefully plotted upon a large scale and prepared for engraving, much detailed study of notes and collections remains to be done. In this preliminary report it is only possible to touch upon such salient features