Geology topics
Source-linked reports with geographic coverage including Texas.
At the request of the U.S. Department of Agriculture, Soil Conservation Service, and the Menard Irrigation Company, a seepage investigation was made on Noyes Canal (Menard Irrigation Company Canal) in Menard County, Texas, from the headgates of the canal to where the canal empties back into the San Saba River.
No abstract available.
The purpose of this report on the geology and ground-water resources of Comal County in central Texas is to determine the sources of the waters that supply Comal Springs, the largest springs in the Southwest, and other springs and wells. Comal County has an area of about 559 square miles and in 1950 had a population of 16,325. Comal Springs discharge within the city limits of New Braunfels, the county seat of Comal County.
These investigations were undertaken at the request of the Texas State Board of Water Engineers and engineers of the Lower Nueces River Water Supply District. The purpose of the investigations was to determine seepage gains or losses along the river and losses in transmission of water from the District's artesian wells near Campbellton to Lake Corpus Christi. The channels of the Atascosa, Frio, Nueces rivers were used to transport the water.
The known quantity of helium in the Texas Panhandle gas reservoir is greater than could be explained by assuming normal geologic conditions. Radon content of the gas varies between about 10 and 250 micromicrocuries per liter (S. T. P.), and the more highly radioactive wells are clustered in several groups. Mathematical analysis indicates that the larger concentrations of radon could not be derived from rocks of normal radioactivity.
A report on the ground-water and surface-water surveys of the Nueces River Basin was included in a report by the Bureau of Reclamation, entitled "Comprehensive plan for water-resources development of the Nueces River Basin project planning report number 5-14.04-3, February 1946".
Unusual drought conditions in the summer of 1948 led the irrigators in the lower Brazos River Valley to request releases from Possum Kingdom Reservoir primarily for the irrigation of rice. The purpose of this study is to determine the time of travel. The first release is identified as that passing the Palo Pinto gage, 20 miles downstream from the reservoir, from August 9 to 16, 1948; the second release is that from August 16 to 30; and the third release is that from August 30 to September 6.
This report is the fifth the a series of publications by the Texas Board of Water Engineers giving chemical analyses of the surface waters in the State of Texas. The samples for which data are given were collected between October 1, 1948 and September 30, 1949. During the water year 25 daily sampling stations were maintained by the Geological Survey. Sampled were collected less frequently during the year at many other points. Quality of water records for previous years can be found in the following reports: "Chemical Composition of Texas Surface Waters, 1938-1945," by W. W. Hastings, and J. H. Rowley; "Chemical Composition of Texas Surface Waters, 1946," by W. W. Hastings and B. Irelan; "Chemical Composition of Texas Surface Waters, 1947," by B. Irelan and J. R. Avrett; "Chemical Composition of Texas Surface Waters, 1948," by B. Irelan, D. E. Weaver, and J. R. Avrett. These reports may be obtained from the Texas Board of Water Engineers and Geological Survey at Austin, Texas. Samples for chemical analysis were collected daily at or near points on streams where gaging stations are maintained for measurement of discharge. Most of the analyses were made of 10-day composites of daily samples collected for a year at each sampling point. Three composite samples were usually prepared each month by mixing together equal quantities of daily samples collected for the 1st to the 10th, from the 11th to the 20th, and during the remainder of the month. Monthly composites were made at a few stations where variation in daily conductance was small. For some streams that are subject to sudden large changes in chemical composition, composite samples were made for shorter periods on the basis of the concentration of dissolved solids as indicated by measurement of specific conductance of the daily samples. The mean discharge for the composite period is reported in second-feet. Specific conductance values are expressed as "micromhos, K x 10 at 25° C." Silica, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, and nitrate are reported in parts per million. The quantity of dissolved solids is given in tons per acre-foot, tons per day (if discharge records are available), and parts per million. The total and non-carbonate hardness are reported as parts per million calcium carbonate (CaCO 3 ). For those analyses where sodium and potassium are reported separately, "recent sodium" will include the equivalent quantity of sodium only. In analyses where sodium and potassium were calculated and reported as a combined value, the "percent sodium" will include the equivalent quantity of sodium and potassium. Weighted average analyses are given for most daily sampling stations. The weighted average analysis represent approximately the composition of water that would be found in a reservoir containing all the water passing a given station during the year after through mixing in the reservoir. Samples were analyzed according to method regularly used by the Geological Survey. These methods are essentially the same or are modifications of methods described in recognized authoritative publications for mineral analysis of water samples. These quality of water records have been collected as part of the cooperative investigations of the water resources of Texas conducted by the Geological Survey and the Texas Board of Water Engineers. Much of the work would have been impossible without the support of the following Federal State, and local agencies The United States Bureau of Reclamation, U. S. Corps of Engineers, Brazos River Conservation and Reclamation District, Lower Colorado River Authority, Red Bluff Water Power Control District, City of Amarillo, City of Abilene, and City of Forth Worth. The investigations were under the firection of Burdge Irelan, District Chemist, Austin, Texas. Analyses of water samples were made by Clara J. Carter, Lee J. Freeman, Homer D. Smith, Dorothy M. Suttle, DeForrest E. Weaver, and Clarence T. Welborn. Calculations of weighted averages were made by James R. Avrett, Burdge Irelan, Dorothy M. Suttle, and DeForrest E. Weaver.
Geologic mapping, supplemented by detailed investigations at the mines, has revealed new information about the geologic structure of the Terlingua quicksilver district, Texas. Attention is focused on the nature and origin of domes, grabens, and breccia pipes, structures that are unusually well developed in the area. The sedimentary rocks, of Cretaceous age, are overlain and intruded by igneous rocks of Tertiary age. Much of the structural deformation was an accompaniment of igneous intrusion. The Terlingua uplift, an irregular dome with a structural relief of several thousand feet, covers about half of the district. The southern boundary of the uplift is a steep monocline. Smaller domes, found throughout the district, were formed by igneous uplift. Evidence for this origin includes exposures of the igneous rock, the occurrence of baked rock on the domes, and theoretical consideration of the forces necessary to form a dome. Almost all the major faults are normal faults bounding depressed tracts, or grabens. Most of the major faults trend northwest; the strike varies markedly, with both sinuous curves and angular turns. The vertical displacement of the grabens below adjacent blocks varies, up to approximately 2,000 feet. Minor faults belong to two sets; one set trends northwest, parallel to the major faults, and the other northeast. Masses of breccia with a pipelike or chimneylike shape have been designated descriptively as breccia-filled pipes, or simply breccia pipes. A total of 76 breccia pipes was mapped, and four typical breccia pipes are described in detail. They range from 75 feet to 500 feet in diameter, and one has been explored vertically for more than 800 feet. The top of one breccia pipe has been found, in the Chisos mine, but the bottom of none has been found. The displacement of the fragments is downward, commonly several hundred feet, and in one instance more than 1,000 feet. The nature of the breccia and its walls indicates collapse due to undermining as the origin of the Terlingua pipes. Features, common to all the pipes, that point to this origin are the downward displacement of the fragments, the absence of drag or thrust structures, the presence of slump structures along the walls, and the vertical cylindrical form. The general structural problems of the district include the age relations, the origin of the uplift, the origin of the domes, and the origin of the grabens. The earliest structural movement involving the Cretaceous rocks was the beginning of rise of the Terlingua uplift. Before this rise ceased, the graben faulting probably began. Volcanism and widespread hypabyssal intrusion, which was accompanied by doming, was partly contemporaneous with graben faulting. The breccia pipes were formed after the beginning, and before the end, of igneous activity. Minor faulting, accompanied by mineralization, continued later than other structural movements, The Terlingua uplift was probably caused primarily by laccolithic igneous intrusion but was influenced by horizontal compression. A basic intrusion, rather than a silicic intrusion, is required to explain the exposed igneous rocks. The geometry of the large grabens indicates that they are relatively superficial accompaniments of horizontal extension. It is suggested that horizontal extension of the upper part of the earth's crust occurred during the formation of the Terlingua uplift and was accompanied by graben faulting.
No abstract available.
No abstract available.
The effect of DDT dust on wildlife was studied at Camp Bullis, Bexar County, Texas, in the summer of 1947. Studies were made on a 206.6 acre plot that was treated with DDT for experimental control of the Lone Star tick ( Amblyomma americanum ). A dust consisting of one part of DDT to nine parts of pyrophyllite was applied at an average rate of 4.4 pounds of DDT per acre. The limits of DDT concentration that affected wildlife cannot be stated exactly because of a heavy rain that fell near the end of the dusting, and because of irregularity in DDT deposition. Since absolute uniformity of dusting could not be expected in any large scale DDT application, the effects observed in these trials were probably fairly representative. However, continued dry weather would have permitted longer exposure to DDT, possibly with more severe effects than those found in this study. The vegetation of the experimental area was roughly 70 percent ungrazed tall-grass prairie and 30 percent trees and shrubs. Ground and bush feeding birds were severely affected. Cardinals, lark sparrows, field sparrows, Bewick's wrens, Carolina wrens, Kentucky warblers, yellow-breasted chats, blue grosbeaks, and painted buntings were nearly or entirely eliminated from the treated area. Birds affected, but less drastically reduced in numbers, were yellow-billed cuckoo, black and white warbler, yellow-throated vireo, and white-eyed vireo. Birds found dead in the DDT area were 9 cardinals, 2 painted buntings, 2 lark sparrows, 1 yellow-breasted chat, and 1 white-eyed vireo. Bird mortality had begun by the day after dusting and was largely over by the end of the fifth day. Census of deer in DDT and check areas before and after treatment showed no reduction in deer numbers and no diminution in use of the DDT area. No deer or fawns were found dead or affected. Box-trapping of raccoons in DDT and check areas before and after treatment showed no effects that could be attributed to DDT. Limited observations on armadillos, striped skunks, and rabbits gave no indication of pronounced damage to these forms. No mammals of any kind were found dead or affected in or near the DDT area. Four rough green snakes and one Texan spiny lizard were found dead in the DDT area. Mortality was probably high among insectivorous reptiles.