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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 757 records · Page 42Linked to original sources
USGS1964

Sedimentology: general introduction and definitions : fluvial sediment and channel morphology

Sedimentology, the study of sedimentary rocks and the processes by which they are formed, includes and is related to a large number of phenomena. Sedimentology includes the five fundamental processes defined by the term sediaentation --weathering, erosion, transportation, deposition and diagenesis. Sedimentology shares with geomorphology the study of the surface features of the earth. Sedimentology also shares with hydrology the study of river.--channels. River channels are formed in part or in total as a result of flowing water and sediment transport, commonly called the "work of the rivers." This survey of published literature was made to aid in arriving at definitions which would be acceptable to, and representative of, a majority of professional personnel actively engaged in laboratory and field investigations related to the "work of the river." The definitions in this list are intended to explain the terms used in studies of fluvial sediment and channel morphology. No set of definitions can expect universal acceptance, however, i t is hoped that this compilation will be considered a summary and synthesis of present and past usage and that it will serve as a starting point for future usage. Multiple references are cited from textbooks, glossaries and dictionaries, scientific journals and u.s. Government publications. To obtain a mutual understanding and enhance precision, many of the proposed definitions are a composite of those selected from papers or reports covering research studies and field investigations. A draft of this glossary has been reviewed by a group of interested personnel. The results of this review have been carefully considered and the originally-suggested definitions have been revised accordingly, resulting in the present compilation. R. G. Wolff, with the help of Mrs. v. Blatcher, carried out the literature search and compilation of terms and the review results. Paul c. Benedict approved or composed the definitions as presented in this report.

Open-File Report↗
USGS2000

Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through 1999

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the Albuquerque Basin are obtained solely from ground-water resources. An increase in the population of about 35 percent from 1980 to 1990 has resulted in an increased demand for water. From April 1982 through September 1983, a network of wells was established to monitor changes in ground-water levels throughout the Albuquerque Basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. Currently (1999), the network consists of 221 wells and piezometers. U.S. Geological Survey personnel collect water-level measurements at sites 1-88 and sites 165-221. Water-level and other data for sites 89-164 are measured by other agencies and reported to the USGS.

Open-File Report↗
USGS2000

Assessment of mineral resource tracts in the Chugach National Forest, Alaska

Locatable minerals have been produced from the Chugach National Forest (CNF) for nearly 100 years. Past gold production has come from the Kenai Peninsula and the Girdwood, Port Wells, and Valdez areas. Copper and by-product gold and silver have been produced from mines at Ellamar, on Latouche Island, and near Valdez. Many of the past-producing properties were not mined out and contain significant inferred reserves of gold, copper, lead, zinc, and silver. This report outlines mineral resource areas (tracts) that contain both identified and undiscovered mineral resources. These tracts were drawn on the basis of one or more of the following criteria: (1) geochemical anomalies, (2) favorable geologic units, (3) presence of mines, prospects or mineral occurrences, and (4) geophysical anomalies. Bliss (1989) used six mineral deposit models to describe the types of deposits known from the CNF. Of these deposit types, only four are sufficiently known and defined in the CNF to be suitable for consideration in outlining and ranking of mineral resource tracts; these deposit types are: (1) Cyprus-type massive sulfide, (2) Chugach-type low-sulfide goldquartz veins, (3) placer gold, and (4) polymetallic vein. The U.S. Bureau of Mines indicated that most of the inferred mineral reserves in the CNF would not be economic to produce under current prices. Small-scale placer gold operations are a possible exception. Other known resources that have recorded past production (oil, coal, rock, sand, and gravel) are not addressed in this report.

Alaska↗
USGS2001

Petrography and physical properties of selected rock types associated with the Hayward Fault, California

This report provides brief petrographic descriptions of rock samples collected from the vicinity of the Hayward Fault, Northern California. Two groups of rock samples are represented here: A set of six samples that were used for laboratory measurements of P- and S-wave velocity , strength, density, and porosity. This group was examined using standard petrographic microscope, scanning electron microscope (SEM) and electron microprobe techniques on polished thin sections. A larger group of samples, most of them 1"-diameter cores, on which density and magnetic susceptibility measurements were made as part of gravity and magnetic surveys of the Hayward Fault. Because this second group of samples received less extensive laboratory study, examination of them was limited to standard petrographic microscope examination of covered thin sections. The density and susceptibility measurements of this second group of samples are included in this report.

California↗
USGS2002

Water-level altitudes 2002 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2001 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

This report is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The Houston-Galveston region comprises Harris, Galveston, Fort Bend, Waller, and Montgomery Counties and adjacent parts of Brazoria, Grimes, Walker, San Jacinto, Liberty, and Chambers Counties. The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District, the City of Houston, and the Fort Bend Subsidence District. For the Chicot and Evangeline aquifers, maps show approximate water-level altitudes in 2002, water-level changes from 2001 to 2002, approximate water-level changes from 1977 to 2002, lines of zero water-level change for intervals increasing in 5-year increments beginning with 1977–82, and approximate water-level changes from 1990 to 2002 (in the Fort Bend subregion [Fort Bend County and adjacent areas]) (figs. 1–10). For the Jasper aquifer, maps show approximate water-level altitudes in 2002 and water-level changes from 2001 to 2002 and 2000 to 2002 (figs. 11–13). The report also contains a map showing extensometer (well equipped with compaction monitor) site locations (fig. 14) and graphs showing measured compaction of subsurface material at selected sites from 1973 or later to 2001 (fig. 15). The U.S. Geological Survey (USGS) has published annual reports of water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region since 1979; and separate annual reports of same for the Fort Bend subregion since 1990. The USGS published its first water-level-altitude map for the Jasper aquifer in the greater Houston area (primarily Montgomery County) in 2001. This year (2002), the altitude and change maps for the three aquifers are in this report.

Texas↗
USGS2002

Fifty-Year Flood-Inundation Maps for Santa Rosa de Aguan, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the coastal municipality of Santa Rosa de Aguan that are prone to oceanic storm-surge flooding and wave action. The 50-year flood on the Rio Aguan (4,270 cubic meters per second), would inundate most of the area surveyed for this municipality and beyond. Therefore a detailed numerical hydraulic model was not developed for this municipality as it was for the others. The 50-year storm surge would likely produce higher water levels than the 50-year flood on the river during normal astronomical tides. The elevation of the 50-year storm surge was estimated to be 4.35 meters above normal sea level, based on hurricane probabilities and published storm-surge elevations associated with various hurricane categories. Flood-inundation maps, including areas of wave-action hazard and a color-shaded elevation map, were created from the available data and the estimated 50-year storm tide. Geographic Information System (GIS) coverages of the hazard areas are available on a computer in the municipality of Santa Rosa de Aguan as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Data Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the maps in much more detail than is possible using the maps in this report.

Santa Rosa de Aguan↗