Geology topics
Research about Texas
Source-linked reports with geographic coverage including Texas.
Rocks of Permian (?) age in the Colorado River Valley, north-central Texas
No abstract available.
Regional geologic map of parts of Culberson and Hudspeth Counties, Texas
No abstract available.
Geology of the Woodbine formation of Cooke, Grayson, and Fannin Counties, Texas
No abstract available.
The bedding-replacement fluorspar deposits of Spar Valley, Eagle Mountains, Hudspeth County, Texas
The Spar Valley fluorspar district in the Eagle Mountains, Hudspeth County, Texas, is one of the few in the western United States containing bedding-replacement fluorspar deposits. The deposits at Spar Valley resemble the bedding-replacement deposits of the Cave in Rock fluorspar district of southern Illinois. Two distinct deposits, the North and the South ore bodies, are present. The North ore body is larger and has been developed by diamond drilling and mining; the following statements apply chiefly to it.The fluorspar partly replaces a sequence of three sandy limestones interbedded with four calcareous shales in the lower part of the Edwards limestone of Lower Cretaceous age. The fluoritized beds, which dip 40 degrees SW in conformity with underlying limestone, are overlain by thick impermeable gouge along a bedding-plane fault dipping slightly more than 40 degrees SW. The high-grade beds were derived from the sandy limestones, and the low-grade beds, which contain as much as 28 percent of CaF 2 , were formed from the calcareous shales. The selectiveness of replacement by the fluorine-bearing solutions, due to differences in the chemical composition, texture, and degree of brecciation of the original rock, resulted in bedding-replacement deposits of variable fluorite content.A reduction in volume, which accompanied the replacement, led to the development of many cavities. During the later stages of fluoritization these cavities were lined with fluorite crystals, early fluorite grains were coated and interstices between them were filled, and fluorite veins were formed in the ore beds and the underlying dense limestone.
Geology of the Southern Guadalupe Mountains, Texas
This report deals with an area of 425 square miles in the western part of Texas, immediately south of the New Mexico line. The area comprises the south end of the Guadalupe Mountains and the adjacent part of the Delaware Mountains; it includes the highest peaks in the State of Texas. The area is a segment of a large mountain mass that extends 50 miles or more northward and southward. The report describes the geology of the area, that is, the nature of its rocks, tectonics, and surface features, and the evidence that they give as to the evolution of the area through geologic time. Incidental reference is made to the geology of surrounding regions in order to place the area in its environment. The Permian system of the southwestern United States has been until recently one of the intriguing but little known subjects of American stratigraphy. In the latter half of the nineteenth century after the western. United States was settled, the "red bed" sections of the Permian were studied and reported on by many geologists, but up to 1920 the existence of a contemporaneous marine sequence in western Texas and southeastern New Mexico was little appreciated. Since that year the discovery of extensive oil fields and potash beds in this region gave an impetus to the study of the Permian rocks, and furnished the geologist with records of hundreds of drill holes from which to deduce the nature of the strata not exposed at the surface. At the same time geologists have studied the rocks in the outcropping areas, and have compared them with the strata encountered by drilling. Much remains to be done in order to understand the history of Permian time in the region. The physical and chemical conditions that caused. the deposition of .the various and often complexly related deposits need to be better understood. More of the fossils of the rich and interesting marine faunas should be described, and the relations of the fossils to their environments should be determined. Further, a satisfactory scheme of correlation is needed, and also a subdivision into series that will express the contemporaneity of strata in different areas. One useful contribution to the solution of these problems is the detailed study of sequences of rocks exposed at the surface in the different mountain ranges of Texas and New Mexico. This report deals with one such sequence of rocks in western Texas, the one exposed in the southern Guadalupe Mountains (fig. 1). Here, the Permian rocks are magnificently exposed, to a thickness of about 4,000 feet (pl. 1). They are all of marine origin, and belong to the middle part of the system, with the base concealed and the top absent. Overlying and underlying beds, however, are found in nearby areas.
Stratigraphy of the upper Cambrian, Llano Uplift, Texas
The two formations and eight members that constitute the Upper Cambrian in the Llano uplift of central Texas are described or redefined, and their lithic characters in 19 measured sections are graphically summarized. Standard reference to them is thus furnished. The Riley formation comprises the basal Paleozoic strata of the Llano uplift. Its initial sediments were deposited on a submerged pre-Cambrian terrane having a known topographic relief as great as 800 feet. Its thickness normally averages about 680 feet but ranges from probably less than 200 to about 800 feet. At most places it is subequally divisible between the Hickory sandstone member below and the Cap Mountain limestone member above, with the thin but widespread, glauconitic Lion Mountain sandstone member capping and completing the sequence. The Wilberns formation includes five named members between the Riley formation and rocks of the Lower Ordovician Ellenburger group. It normally averages about 580 feet thick and ranges from 540 to 610 feet thick, but in the southeastern corner of the Llano uplift truncation of the upper beds has reduced it to 360 feet. The thin but widespread, nonglauconitic Welge sandstone member introduces the sequence. Above it is the Morgan Creek limestone member, grading to the succeeding argillaceous beds of the Point Peak shale. At the top of the sequence are the San Saba limestone and Pedernales dolomite members. These two are essentially equivalent and gradational facies, with the Pedernales normally overlying the San Saba.
An outbreak of pasteurellosis in wild ducks
A report was received by Merovka that a large number of wild ducks had been found dead on a small lake located about 15 miles southwest of Dimmitt, Castro County, Texas. The area was visited by Merovka and U.S. Game Agent Boone, who found and picked up 307 dead ducks, nearly all mallards and pintails. The farmer on whose land the birds were found stated that tot he best of his knowledge and belief the birds had all perished on Feb. 27, 1944. Field examination of the birds indicated that they had died at approximately that time. Only 1 sick bird was observed during the field investigation.
Food habits of the raccoon in eastern Texas
Explore the source record for details and available documents.
248 mine, Terlingua quicksilver district, Brewster County, Texas
The 248 quicksilver mine is in Section 248, Block G-4, 2 miles east of Terlingua and 86 miles by dirt road from Alpine, Tex., the nearest railway shipping point (see accompanying maps). Cinnabar, the quicksilver mineral, was discovered before 1902. By 1934 there were only about 700 feet of subsurface workings, but in recent years the Esperado Mining Co., which has the property under lease, has greatly extended exploratory workings and has built a Herreshoff furnace rated at 40 tons per day. At the present time there are 1 1/3 miles of underground workings and 800 feet of surface trenches.
The Mariposa mine, Terlingua quicksilver district, Brewster County, Texas
The Mariposa mine in Brewster County, Tex., ranks second in all-time production of quicksilver in the Terlingua mining district. It is in Section 59, Block G-12, and is about 7 miles by road west of the Terlingua Post Office (see accompanying maps). The nearest railroad shipping point is Alpine, Tex., which. is 93 miles by road to the north. The mine is now controlled by the Esperado Mining Co. of Houston, Tex. Since 1895 the Mariposa mine has produced between 20,000 and 30,000 flasks of quicksilver. The major production was before 1911, but the mine was active during the first World War, and again during the period from 1933 to 1942. In February 1944, the Esperado Mining Co, was reworking some of the old dumps and exploring an ore showing in the east wall of the Perry pit. The productive ground, a rectangular area roughly 3,500 feet long and 1,000 feet wide, centers about California Hill (see plate 1). The principal subsurface workings, about 3 miles of drifts, stapes, and crosscuts, are under California Hill, but much of the ore was taken from numerous pits, trenches, and shafts northeast and west of the hill. Of the 121 shafts over 20 feet deep, 6 are over 100 feet deep and. 2 of these, No. 5 (or Cruz) shaft and the finite shaft, are 300 or more feet deep. The Contratiro winze (see map of workings) extends 200 feet below the 100 level of the mine. Several thousand feet of drifts and crosscuts extending from the deeper shafts explore the mineralized ground through a vertical range of about 300 feet, but almost all the ore that has been produced came from the uppermost workings.
Geologic map of southern Guadalupe Mountains, Hudspeth and Culberson Counties, Texas
No abstract available.