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Results for “Open-File Report”

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 19 recordsLinked to original sources
USGS2025

Grand Canyon River Alert System—Implementing an emergency alert system for wilderness recreation

The Grand Canyon River Alert System (GCRAS) provides government-issued emergency alerts to wilderness recreationalists in the Grand Canyon, who are often outside the bounds of cellular signal reception. GCRAS is a collaboration between the U.S. Geological Survey (Grand Canyon Monitoring and Research Center), National Weather Service, Coconino County Emergency Management, and National Park Service. Technological advances in satellite communications have improved satellite signal availability in remote areas and increased the reliability of satellite communications using personal devices such as commercially available satellite messaging devices. These advancements have presented an opportunity to create a novel emergency alert system designed primarily for backcountry visitors to provide improved communications for periods of increased risk and potentially dangerous situations in the backcountry. GCRAS is designed specifically for the distinctive needs of satellite messaging devices and features reduced character count messages, short-code signup capability, and the ability to unsubscribe at any time. After a positive test of the system in March 2024, the system went live to the public and has been used more than two dozen times in 2024 to inform boaters and hikers of hazards (such as debris flows and flash floods) in the Grand Canyon. Satellite signal availability and device response time varies based on location and service provider, but initial testing showed messages arriving within 2–10 minutes. Although GCRAS was developed specifically for the Grand Canyon, the GCRAS framework could be applied to other wilderness areas. It can be used by emergency management authorities, land-management agencies, search and rescue units, and those concerned with public safety to help increase communication with people visiting or living in areas that are outside the signal of more traditional emergency-notification methods, such as cellular, wireless emergency alerts, and sirens.

Arizona↗
USGS1976

Trace elements in some rocks and slag from the Yemen Arab Republic and their bearing on the iron ore near Sa'dah

Thirty-seven samples of rocks, saprolite, laterite, gossan, and slag were collected in the Yemen Arab Republic during June-July 1975 when field work was conducted to refine an interpretation of the regional geology made from LANDSAT-1 images by M. J. Grolier. These samples we reanalyzed in the laboratories of the U. S. Geological Survey, and the results were interpreted for use in programs of economic development as a guide for the evaluation of mineral resources in the Yemen Arab Republic. The work was undertaken as part of the program of the U. S. Agency for International Development with the cooperation of the Mineral and Petroleum Authority, Ministry of Economy, Yemen Arab Republic.

Open-File Report↗
USGS1976

A comparison of electronic particle counting and pipette techniques in routine mud analysis

Electronic particle counting and pipette size-analysis techniques are compared for their relative effectiveness in large-scale routine mud analysis. Optimum laboratory procedures for conducting electronic analyses with a Model TA Coulter Counter are presented. Comparative electronic and pipette analyses conducted on the same samples resulted in equivalent precision for both techniques. Results of electronic analyses consistently showed size distributions significantly coarser than those obtained by pipette analyses. The laboratory efficiency of the relatively rapid electronic technique is far superior to that of the pipette technique, although more extensive precautionary measures are required to maintain a high level of analytical accuracy and precision. The quality of electronic analyses largely depends upon the effectiveness of standardized operational procedures established within the laboratory.

Open-File Report↗
USGS1976

Water resources of Dinosaur National Monument, Colorado and Utah

Dinosaur National Monument, partly in the Rocky Mountain System and partly in the Colorado Plateaus physiographic province, covers an area of 322 square miles (834 square kilometres) in northwestern Colorado and northeastern Utah. The climate is generally cool and pleasant in May, early June, September, and October; winters are cold. Normal annual precipitation ranges from less than 8 to more than 16 inches (203 to 406 millimetres). Geologic formations in the monument range in age from upper Precambrian to Holocene, but not all ages are represented. The monument is on the south limb of the east-trending regional fold representing the Uinta Mountains. Faults and subsidary folds on the south slope of the Uinta Mountains complicate the geology and hydrology of the area. None of the surface streams in the monument are diverted for public supply, but the Green and Yampa Rivers are a recreational resource for boaters. The flow of the Green River is regulated by Flaming Gorge Reservoir; however, flood potentials are estimated for the Yampa River and three smaller streams. Facilities in the monument are not endangered by probable mean annual floods, but may sustain some damage to facilities by the 25- or 50-year floods. Major aquifers in the monument are sandstone and limestone formations, but these formations are drained in the higher areas. Alluvium along the major stream channels yields small amounts of water to wells, but some of the water is not of suitable chemical quality for public supply. All public water supplies in 1971 were obtained from wells, and the use of water during 1970 was estimated to be 15 million gallons (46 acre-feet or 0.057 cubic hectometres). Most of the ground water obtained from sandstone and limestone is of suitable chemical quality for public supply.

Colorado, Utah↗
USGS1978

Erosion, sediment discharge, and channel morphology in the Upper Chattahoochee River basin, Georgia

Average annual rates of sheet erosion and sediment discharge were computed for several watersheds in the Upper Chattahoochee River basin in Georgia. Erosion yields ranged from about 900 to 6,000 tons per year per square mile in nine watersheds and were greatest where land use is largely agricultural or transitional. Suspended sediment yields from the same watershed ranged from about 300 to 800 tons per year per square mile and were greatest from urban areas and least from mostly forested watersheds. The impact of suspended sediment on stream quality was evaluated for 14 watersheds. In general, 60 percent or more of the total annual discharge of trace metals and phosphorus was contributed by suspended sediment. Yields of trace metals and nutrients in suspension were consistently greater in urban watersheds. Turbidity in basin streams increased geometrically with increasing concentrations of suspended sediment. (Woodard-USGS)

Georgia↗
USGS1978

Ages of flow units in the far eastern lunar maria based on crater density

The distribution of major geologic units of uniform relative age exposed in the far eastern maria (i.e., Mare Marginis, Mare Smythii, and Mare Crisium) and Mare Humorum was compiled in map form on the basis of a crater density mapping technique. Correlation of crater densities and radiometric ages of Apollo landing sites provide estimates of the absolute age for the units. Results indicate that the far eastern maria were emplaced over a period of approximately 1.25 b.y., from about 3.75 b.y. to 2.5 b.y. before present. Extensive young mare units (~ 2.5 ± 0.5 b.y.) occur in all three large far eastern maria. Major old units (~ 3.65 ± 0.05 b.y.) occur in central Mare Crisium and eastern Mare Marginis. Correlation of the age data and remote sensing data suggests that: (1) both young and old units have relatively high Mg/A1 ratios and are relatively rich in Fe and Ti, whereas intermediate age units have lower Mg/Al ratios and less Fe and Ti. A similar relationship previously noted for other maria suggests that this applied throughout the lunar maria; (2) older units generally have higher remnant magnetism than younger units - a relationship also previously noted for other lunar maria and attributed to a steady decline of a primodial lunar magnetic field, and (3) all age units in the eastern maria have relatively low natural radioactivity or abundances of Th, K, and U compared to the western maria (particularly in the Mare Imbrium area). The presence of young lava flows in both the eastern and western maria suggests that the relative abundance of these radioactive elements has played only a minor role in controlling the duration and location of mare volcanism. The crater-density relative age data presented here correlate in a linear fashion with crater-morphology relative age data. A combination of these data provides a nearly complete map of the distribution of units of uniform relative age of the lunar maria and shows that, as previously suggested, the older units (> 3.5 b.y. old) are generally located along the basin edges and the younger units (< 3.5 b.y. old) are generally in the basin centers. However, this map also shows that the vents for the flows of the young units must be located on the edges of the basins. These observations support tectonic models of basin subsidence caused by isostatic adjustment to the weight of the lava and to subsurface evacuation and subsequent collapse as the lavas were erupted.

Open-File Report↗
USGS1979

Preliminary results of the Sabkhah Hazawza gravity project, Wadi as Sirhan area, Kingdom of Saudi Arabia

One hundred thirty seven new gravity stations at an average station density of one station per 17.5 km2 have been established in a 40 x 60 km area centered on Sabkhah Hazawza in the northwestern part of the Kingdom of Saudi Arabia. A successful tie to existing Arabian American Oil Co. (ARAMCO) gravity data was made and a simple Bouguer gravity anomaly map was compiled during the survey. The map shows a distinct gravity low of about -8 mgal associated with the sabkhah, its minimum displaced to the northeast of the longitudinal axis of the sabkhah. However, the continuation of the gravity anomaly under the basalt field to the northeast suggests that the gravity anomaly is due to an older basin-like structure. If the sabkhah deposits are due to damming of ancient Wadi as Sirhan by basalt flows, then the deposits are probably thin. Preliminary estimates give a maximum thickness of about 270 m for the sedimentary fill causing the gravity anomaly.

Wadi as Sirhan area↗