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REPORT OF GEOLOGIST FOR WESTERN TEXAS

E. T. Dumble, Esq., State Geologist, Austin, Texas:

SIR—I left Austin October 3rd, A. C. I arrived at Sierra Blanca October 5th. The tent and barometer addressed to that place not having previously arrived, and not arriving during that day, I left for El Paso October 6th, leaving directions to forward the barometer. The tent, when it should arrive, I desired to be stored with Mr. Hutchins in Sierra Blanca until called for.

In El Paso I bought a team of light mules and a "South Bend " wagon at reasonable prices, had the wagon changed and fitted up to suit the purposes of the expedition, bought a camp outfit, and engaged men.

In obedience to your instructions to confine my work to the examination of the more important parts of the country, and not to make a detailed survey of any particular locality, I concluded to go over as much ground as possible, to make short stops only at such places as appeared to be of most importance with reference to economical geology, and to confine myself especially to this branch of the survey. I thought that in this manner I would best fulfill the spirit of the geological bill and serve the interests of the state.

October 11th.—I started to the Franklin range of the Organ Mountains, north of El Paso.

The mesa or high prairie land, which begins about three miles northeast of El Paso, rises nearly 200 feet above the level of the city, and at a somewhat greater distance it rises nearly 400 feet above that level. Its soil is a rich loamy sand of quaternary age, being the product of the decomposed rocks of the surrounding mountains. Its vegetation consists mostly of gramma grass, Spanish daggers, cactus, greasewood, and catclaws.

If it were possible to irrigate this, it would make excellent farming land, equal to the best in the state. This flat spreads between the Franklin range on the west and the Hueco Mountains on the east. The soil is mixed and covered with gravel only in the vicinity of the mountains.

The foothills consist mostly of a conglomerate of pebbles and boulders varying from a quarter of an inch in diameter to ten and twelve inches, and consist in part of limestone, granitic, and porphyritic rocks, quartz, quartzites, jasper, etc., with very few fragments of petrifactions of different periods. Under the fertile soil of the mesa, which, as some dry water-courses show, is from two to four feet thick, a number of well rounded pebbles of various sizes and material, evidently the debris of the foothill conglomerates, begin. I estimate the depth of this layer, which is imbedded near the surface in sandy, loamy, and calcareous soil, at not less than fifty to seventy feet, below which depth the calcareous deposits begin.

The whole mesa is "flat as a dollar," spreads about twenty-five miles east and west, and beginning near El Paso, extends far over the boundary line of Texas into New Mexico. This mesa is evidently a part of a former lake bed, although about 200 feet above the level of the prairies south and east of it.

Irrigation from artesian wells or the Rio Grande River is out of the question, but some of the valleys in the foothills and the mountains might be dammed at a comparatively small cost to form reservoirs of considerable size. Judging from the traces of washing in the water-courses, very heavy rains fall in this part of the state, by which such reservoirs would be supplied.

The float rocks from the mountains indicate that the rocks of the Franklin mountains are granite, granulyte, feldspar, and augitic porphyries, such as greenstone porphyry and melaphyre, and crystalline limestones. I found this confirmed by walking into the mountains proper and climbing along the steep slopes. The plutonic, and in some places the volcanic formations named above, are partly capped by crystalline limestone partly metamorphosed, which covers also the greater parts of the slopes on the river or western side.

Of the four springs on the eastern side of the mountains, only Monday Springs, thirteen miles from El Paso, contained water in sufficient quantity for camp purposes; another, four miles farther north, is higher up in the mountains and its water supply had dwindled down to a few gallons in twenty-four hours. The mountains of the Franklin range show, from a hurried and consequently superficial inspection, many good ore indications in the shape of whitish, yellowish, and reddish decomposed streaks, particularity in contacts, outblows of strongly ferruginous quartzites, and calcareous outcroppings.

The physiological effects of the water on myself and on my men, leads me to believe that the ores will be found in the shape of tellurides. This might account for the scarcity of older Spanish and Mexican prospects and mines, the tellurides not having been as well known to the Mexicans and Spaniards as the sulphides, carbonates, chlorides, etc.

In spite of this there exist traditions of mines successfully worked by Franciscan monks (for instance the "Padre" mine), but as is generally the case in such instances, either nobody knows the exact location, or the small holes and dumps contradict the truth of the traditions of extensive mines.