The object of this work was to determine the age of the Guadalupe mountains, their geological structure and relation to the strata east of the mountains with particular reference to the artesian water supply of the Plains, and the prospects of the district for coal and other minerals. Circumstances prevented the completion of these plans and consequently the work was done in much less detail than was at first intended. Instead of four months, as was at first planned, only two months were spent in the field and less than one month in the mountains. Furthermore, there being no topographic map of the region and it being impossible to make detailed observations in consequence, the work has necessarily been general rather than of a detailed nature. For these reasons this report is no more than a reconnoissance. Still it has been possible to add something to the knowledge of this region, both of the geology and the economic resources as revealed by the geology.

In order to become familiar with the Permian beds of Central Texas so that they might be recognized, if they existed in the Guadalupe mountains, as reported, it was considered desirable to make a hurried trip across the Permian, thus connecting the Carboniferous area which the writer had previously studied with the Carboniferous of the Trans Pecos region. In this reconnoissance journey more than a month was spent in constant driving westward and the country from Lampasas to the Guadalupe mountains was hurriedly traversed. The advantage of this in the subsequent work was inestimable. The remaining time at my disposal, less than a month, was spent in and about the mountains.

The first authentic information about the geology of these mountains came from Dr. George G. Shumard, who was, in the year 1855 appointed geologist to the expedition under Capt. John Pope, of the U. S. A., ordered by the War Department to test the practicability of obtaining artesian water on the plains of Texas and New Mexico. This eminent geologist and explorer described quite accurately, as was his custom, the region which he traversed, and there are but few points in which my observations, in any essential particular, disagree "

Observations on the Geological Formations of the Country between the Rio Pecos and the Rio Grande, etc., G. G. Shumard. Trans., St. Louis Academy of Sciences, 1858, pp. 273-289.