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USGS1916

The Navajo country: A geographic and hydrographic reconnaissance of parts of Arizona, New Mexico, and Utah

To my mind the period of direct contact with nature is the true "heroic age" of human history, an age in which heroic accomplishment and heroic endurance are parts of the daily routine. The activities of people on this stage of progress deserve a place among the cherished traditions of the human race. I believe also that the sanest missionary effort includes an endeavor to assist the uncivilized man in his adjustment to natural laws. With these ideas in mind the opportunity to conduct exploratory work in the Navajo country appealed to me with peculiar force. Within this little-known region are the remnants of an almost extinct race whose long occupation of the country is recorded in ruined dwellings and abandoned fields. This country is also the home of the vigorous and promising Navajos - a tribe in remarkably close adjustment to their physical surroundings. To improve the condition of this long-neglected but capable race, to render their life more intelligently wholesome by applying scientific knowledge, gives pleasure in no degree less than that obtained by the study of the interesting geologic problems which this country affords.

Arizona, New Mexico, Utah↗

USGS1952

Preliminary report on diamond-drill exploration on Outlaw Mesa, Mesa County, Colorado

Outlaw Mesa is northeast of the Dolores River, about 10 miles southeast of Gateway, Mesa County, Colo. It is an oval-shaped area of about 17 square miles lying mostly within T. 50 N., R. 17 W«, and T. 50 No, R. 18 W., New Mexico principal meridian. The area is accessible by three unimproved roads from Colorado Highway 141. The altitude of the mesa ranges from about 5,500 feet to over 7,000 feet. Total production from Outlaw Mesa from 1914 to 1949 was about 4,000 tons of carnotite ore, having an estimated grade of about 0.50 percent U30Q and 2.5 percent V 2 O 5 . The production from 1949 to October 1951 was about 18,000 tons, having an estimated grade of about 0.35 percent U 3 O 8 and 1.6 percent V 2 O 5 . About 80 percent of the production from 1949 to October 1951 was from deposits discovered by U. S. Geological Survey diamond-drilling in public land, now leased to the Climax Uranium Co. A more complete history of mining and production OE Outlaw Mesa has been given in earlier reports. The results of Geological Survey exploration on Outlaw Mesa are summarized in this preliminary report. A final and more comprehensive report will be transmitted later. No additional drilling is planned.

Colorado↗

USGS2011

A new tool to assess groundwater resources in the Mississippi embayment

What is the Mississippi Embayment? The Mississippi embayment study area encompasses approximately 78,000 square miles in eight States and includes large parts of Arkansas, Louisiana, Mississippi, and Tennessee, and smaller areas of Alabama, Illinois, Kentucky, and Missouri (fig. 1). The Mississippi embayment is essentially a basin that slopes toward the Gulf of Mexico and is filled with sediments of alternating sand, silt, and clay layers. There are two principal aquifers in the embayment-the Mississippi River Valley alluvial aquifer (alluvial aquifer) and the middle Claiborne aquifer (fig. 1). The shallow alluvial aquifer is the primary source of groundwater for irrigation in the largely agricultural region, while the deeper middle Claiborne aquifer is a primary source of drinking water for many of the 5.2 million people living in the embayment. The U.S. Geological Survey (USGS) is conducting large-scale multidisciplinary regional studies of groundwater availability for the Nation. Studies comprise individual assessments of regional groundwater-flow systems that encompass varied terrains and document a comprehensive regional and national perspective of groundwater resources. Collectively, these studies are the foundation for the national assessment of groundwater availability and are conducted in cooperation with other Federal, State, local governments, and the private sector. Numerical groundwater-flow models are used in these studies to document effects of human activities and climate variability on groundwater levels, changes in aquifer storage, and flow between groundwater and surface-water bodies. As part of the Mississippi Embayment Regional Aquifer Study (MERAS), a numerical model was constructed of 13 layers over 78,000 square miles representing multiple aquifers and confining units for the period of 1870 to 2007. The model is a tool that was used to assess and better understand groundwater resources.

Mississippi↗

USGS2026

Regional models for postfire debris-flow likelihood and rainfall thresholds across the western United States

The U.S. Geological Survey (USGS) uses an empirical model developed with logistic regression (the ‘M1’ model) to rapidly assess debris-flow likelihood and to identify quantitative rainfall thresholds for debris flows after wildfire in the western United States. The M1 model was calibrated to a debris-flow inventory from southern California (United States) and has been applied throughout the western United States. Limited spatial coverage in the calibration dataset has motivated evaluation of M1 model accuracy outside the calibration region (e.g., the Sierra Nevada or the eastern Cascade Range, United States). Previous test cases showed that M1 overpredicts debris-flow likelihood and underpredicts rainfall thresholds for some locations (e.g., Arizona, northern California, Colorado, New Mexico, United States). We sought to improve the regional applicability of a debris-flow likelihood model by expanding the debris-flow inventory used for calibration, testing multiple potential models and generating an updated model framework. The updated inventory includes 3788 observations from 67 burned areas paired with short duration rainfall ratios. The updated model framework consists of a modified model structure and sets of coefficients calibrated separately to the entire updated inventory and to subsets of the inventory that intersect three Environmental Protection Agency (EPA) Level 2 ecoregions (Mediterranean California, Upper Gila Mountains and Western Cordillera). Comparisons of predictions from the updated models with observed rainfall and debris-flow activity show that the updated models outperform the M1 model by ~15%–60% and improve the uniformity of predictive performance across the western United States. The updated models also reduce false positive rates relative to M1 and generate rainfall thresholds that are better aligned with relative differences in regional climatology and debris-flow activity.

Arizona, California, Colorado, Idaho, Montana, Nev↗

USGS1995

Hydrochemistry of aquifer systems and relation to regional flow patterns in Cretaceous and older rocks underlying Kansas, Nebraska, and parts of Arkansas, Colorado, Missouri, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming

Aquifer systems in Cretaceous and older rocks of the Central Midwest are divided on the basis of hydrochemistry and ground-water flow patterns in the Plains subregion, the Western Interior Plains aquifer system contains sodium chloride type water with large concentrations of dissolved solids. Ion ratios suggest that the water was derived from seawater by concentration and by depletion of calcium and sulfate ions. In the overlying Western Interior Plains confining system, concentrations of depositional sea water and dissolution of extensive evaporite deposits have resulted in sodium chloride type water with large concentrations of dissolved solids and sodium. Overlying this confining system in the northwest part of the study area, the Great Plains aquifer system yields water that generally is less mineralized and more variable in water type than the underlying systems. Recharge of meteoric water, concentration of brackish water in which the rocks were deposited, and dissolution of underlying evaporite deposits have contributed to the observed water chemistry. The Great Plains confining system restricts the exchange of water between the underlying Great Plains aquifer system and the overlying unconfined aquifers. In the Ozark subregion, geological units equivalent to the Western Interior Plains aquifer system comprise the Ozark Plateaus aquifer system. Units of this aquifer system are exposed at the land surface, and fresh meteoric water moves rapidly through fractures and solution openings. Water chemistry in this system reflects primarily the dissolution of the predominately carbonate rocks.

Water-Resources Investigations Report↗

USGS1999

A global digital elevation model - GTOP030

GTOP030, the U.S. Geological Survey's (USGS) digital elevation model (DEM) of the Earth, provides the flrst global coverage of moderate resolution elevation data. The original GTOP30 data set, which was developed over a 3-year period through a collaborative effort led by the USGS, was completed in 1996 at the USGS EROS Data Center in Sioux Falls, South Dakota. The collaboration involved contributions of staffing, funding, or source data from cooperators including the National Aeronautics and Space Administration (NASA), the United Nations Environment Programme Global Resource Information Database (UNEP/GRID), the U.S. Agency for International Development (USAID), the Instituto Nacional de Estadistica Geografia e Informatica (INEGI) of Mexico, the Geographical Survey Institute (GSI) of Japan, Manaaki Whenua Landcare Research of New Zealand, and the Scientific Committee on Antarctic Research (SCAR). In 1999, work was begun on an update to the GTOP030 data set. Additional data sources are being incorporated into GTOP030 with an enhanced and improved data set planned for release in 2000.

Fact Sheet↗

USGS1955

Carnotite resources of San Miguel bench, Montrose County, Colorado

San Miguel bench includes about 4 square miles in the southern part of T. 48 N., R. 17 W., New Mexico principal meridian, Montrose County, Colorado. Production of carnotite ore from the area has been about 15,000 short tons having an estimated average grade of 0.31 percent U 3 O 8 and 1.6 percent V 2 O 5 . Nearly all of the carnotite deposits occur in a single continuous sandstone bed near the top of the Salt Wash member of the Jurassic Morrison formation. These deposits consist chiefly of sandstone impregnated with uranium- and vanadium-bearing minerals. They are irregular tabular-shaped masses ranging in size from a few short tons to 30,000 short tons or more of minable carnotite ore. During the period November 27, 1951, to April 17, 1953, the U.S. Geological Survey drilled 309 holes totaling 92,194 feet on the San Miguel bench. Reserves total about 43,000 short tons of material 1 foot or more thick and contain 0.10 percent or More U 3 O 8 or 1.0 percent or more V 2 O 5 . Of these reserves 3,300 short tons occur in private land. These reserves are in ten deposits found by Geological Survey drilling. Potential reserves (reserves based on geologic evidence only) are predicted to total about 15,000 short tons, averaging 0.30 percent U 3 O 8 and 1.6 percent V 2 O 5 . No additional drilling in the San Miguel bench is planned by the Geological Survey. Some drilling by private enterprise is recommended.

Colorado↗

USGS1995

Beyond the petroleum system: GEOHORIZONS

The first joint AAPG/AMGP (Association of Mexican Petroleum Geologists) Hedberg Conference on “Geologic Aspects of Petroleum Systems” was held October 2–6, 1994, in Mexico City, Mexico. This research conference attracted nearly 150 geoscientists from 15 countries; 41 papers and 27 posters were presented. The opposite response occurred when the petroleum-system concept was presented more than 20 yr ago; it was largely overlooked. In the past decade, however, interest in this concept as an exploration tool has been growing rapidly. The research conference addressed the concept itself, its elements and processes, the tools and methods used to identify a petroleum system, and many case studies. We summarize responses by the participants to the following three questions. First, what is gained from using the petroleum-system concept? Second, in what new directions will the petroleum-system concept take us in the future? Third, has anything new come out of this research conference?

American Association of Petroleum Geologists Bulle↗

USGS2015

National assessment of shoreline change: historical change along the north coast of Alaska, U.S.-Canadian border to Icy Cape

Beach erosion is a persistent problem along most open-ocean shores of the United States. Along the Arctic coast of Alaska, coastal erosion is widespread, may be accelerating, and is threatening defense and energy-related infrastructure, coastal habitats, and Native communities. As coastal populations continue to expand and infrastructure and habitat are increasingly threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There also is a need for a comprehensive analysis of shoreline change with metrics that are consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along the open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline change so that periodic, systematic, and internally consistent updates regarding coastal erosion and land loss can be made nationally. This report on shoreline change along the north coast of Alaska, between the U.S.-Canadian border and Icy Cape, is one in a series of regionally focused reports on historical shoreline change. Previous investigations include analyses and descriptive reports for the coasts of the U.S. Gulf of Mexico, the Southeast Atlantic, California, the New England and Mid-Atlantic, portions of Hawaii, and the Pacific Northwest coasts of Oregon and Washington. Similar to the earlier reports in this series, this report summarizes the methods of analysis, documents and describes the results of the analysis, and explains historical trends and rates of shoreline change. This Alaska shoreline change assessment differs from previously published shoreline change assessments in that: (1) only two historical shorelines (from the 1940s and 2000s eras) were available for the Alaska study area whereas four or more shorelines (from 1850 to 2002) were available for the other assessments and, thus, only end-point rates for one long-term analysis period are reported here, compared to a combination of long-term and short-term rates as reported in other studies; (2) modern (2000s era) shorelines in this study represent a visually derived land-water interface position versus an elevation based, tidally referenced shoreline position; and (3) both exposed open-ocean and sheltered mainland-lagoon shorelines and rates of change are included in this study compared to other locations where only exposed open-ocean sandy shorelines or bluff edges were evaluated. No distinction was made between sand or gravel beaches, and the base of the unconsolidated coastal bluff was considered the shoreline where no fronting beach existed.

Alaska↗

USGS1978

Discrimination of fluvial and eolian deposits by number-frequency analysis of sediments of sand through silt size from a point bar, Rio Puerco, New Mexico

Fluvial and eolian deposits are interbedded in ephemeral-stream, arid-region point bars in the channel of the Rio Puerco, west of Albuquerque, N. Mex. Number frequency distributions of grain size for both types of deposits were obtained using an electronic automatic image analyzer for a suite of 10 samples. The number-frequency results were superior to weight-frequency (sieve) results in discriminating between eolian units and fluvial units in a vertical point-bar sequence. The image-analysis technique also identified those fluvial deposits whose size distributions have been altered significantly by winds, as well as fluvial deposits that do not show a prominent eolian-process component.

New Mexico↗

USGS2011

National Assessment of Shoreline Change; historical shoreline change along the New England and Mid-Atlantic coasts

Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of this study, the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the New England and Mid-Atlantic coasts is the fifth in a series of reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the Gulf of Mexico, the Southeast Atlantic, and, for California, the sandy shoreline and the coastal cliffs. The rates of change presented in this report represent conditions up to the date of the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. Because of the geomorphology of the New England and Mid-Atlantic (rocky coastlines, large embayments and beaches) as well as data gaps in some areas, this report presents beach erosion rates for 78 percent of the 1,360 kilometers of the New England and Mid-Atlantic coasts. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long-term shoreline change for the New England and Mid-Atlantic coasts was -0.5 meters per year with an uncertainty in the long-term trend of plus or minus 0.09 meters per year. The rate is based on shoreline change rates averaged from 21,184 individual transects, of which 68 percent were eroding. In both the long and short term, the average rates of shoreline change for New England and the Mid-Atlantic were erosional. Long-term erosion rates were generally lower in New England than in the Mid-Atlantic. This is a function of the dominant coastal geomorphology; New England has a greater percentage of shore types that tend to erode more slowly (rocky coasts, pocket beaches, and mainland beaches), whereas the Mid-Atlantic is dominated by more vulnerable barrier islands and dynamic spit/inlet environments. However, the percentage of coastline eroding was higher in New England than in the Mid-Atlantic, highlighting that although rates of shoreline erosion may not be extreme, coastal erosion is still widespread along this region of the U.S. coastline. The average rate of short-term shoreline change for the New England and Mid-Atlantic coasts was also erosional but the rate of erosion decreased in comparison to long-term rates. The net short-term rate as averaged along 17,045 transects was -0.3 meters per year. Uncertainties for these rates range from 0.06 to 0.1 meters per year depending on the data sources used in the rate calculations. Of transects used to measure short-term change, 60 percent were erosional, as compared to 65 percent of coast eroding in the long term. The slight decrease (5 percent) in the amount of coastline eroding may be related to an increase in the frequency and extent of nourishment programs and (or) the effects of hardened structures during the more recent time period. The most stable (lower rates of erosion) beaches were more commonly found in New England. Despite an overall lowering of the average rates of erosion from long-term to short-term, the amount

Open-File Report↗

USGS2014

Seismic investigation of gas hydrates in the Gulf of Mexico: 2013 multi-component and high-resolution 2D acquisition at GC955 and WR313

The U.S. Geological Survey led a seismic acquisition cruise at Green Canyon 955 (GC955) and Walker Ridge 313 (WR313) in the Gulf of Mexico from April 18 to May 3, 2013, acquiring multicomponent and high-resolution 2D seismic data. GC955 and WR313 are established, world-class study sites where high gas hydrate saturations exist within reservoir-grade sands in this long-established petroleum province. Logging-while-drilling (LWD) data acquired in 2009 by the Gulf of Mexico Gas Hydrates Joint Industry Project provide detailed characterization at the borehole locations, and industry seismic data provide regional- and local-scale structural and stratigraphic characterization. Significant remaining questions regarding lithology and hydrate saturation between and away from the boreholes spurred new geophysical data acquisition at these sites. The goals of our 2013 surveys were to (1) achieve improved imaging and characterization at these sites and (2) refine geophysical methods for gas hydrate characterization in other locations. In the area of GC955 we deployed 21 ocean-bottom seismometers (OBS) and acquired approximately 400 km of high-resolution 2D streamer seismic data in a grid with line spacing as small as 50 m and along radial lines that provide source offsets up to 10 km and diverse azimuths for the OBS. In the area of WR313 we deployed 25 OBS and acquired approximately 450 km of streamer seismic data in a grid pattern with line spacing as small as 250 m and along radial lines that provide source offsets up to 10 km for the OBS. These new data afford at least five times better resolution of the structural and stratigraphic features of interest at the sites and enable considerably improved characterization of lithology and the gas and gas hydrate systems. Our recent survey represents a unique application of dedicated geophysical data to the characterization of confirmed reservoir-grade gas hydrate accumulations.

Gulf Of Mexico↗

USGS2013

Historical methane hydrate project review

In 1995, U.S. Geological Survey made the first systematic assessment of the volume of natural gas stored in the hydrate accumulations of the United States. That study, along with numerous other studies, has shown that the amount of gas stored as methane hydrates in the world greatly exceeds the volume of known conventional gas resources. However, gas hydrates represent both a scientific and technical challenge and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of gas hydrates in nature, (2) assessing the volume of natural gas stored within various gas hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural gas hydrates, and (5) analyzing the effects of methane hydrate on drilling safety. Methane hydrates are naturally occurring crystalline substances composed of water and gas, in which a solid water-‐lattice holds gas molecules in a cage-‐like structure. The gas and water becomes a solid under specific temperature and pressure conditions within the Earth, called the hydrate stability zone. Other factors that control the presence of methane hydrate in nature include the source of the gas included within the hydrates, the physical and chemical controls on the migration of gas with a sedimentary basin containing methane hydrates, the availability of the water also included in the hydrate structure, and the presence of a suitable host sediment or “reservoir”. The geologic controls on the occurrence of gas hydrates have become collectively known as the “methane hydrate petroleum system”, which has become the focus of numerous hydrate research programs. Recognizing the importance of methane hydrate research and the need for a coordinated effort, the U.S. Congress enacted Public Law 106-‐193, the Methane Hydrate Research and Development Act of 2000. This Act called for the Secretary of Energy to begin a methane hydrate research and development program in consultation with other U.S. federal agencies. At the same time a new methane hydrate research program had been launched in Japan by the Ministry of International Trade and Industry to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. Since this early start we have seen other countries including India, China, Canada, and the Republic of Korea establish large gas hydrate research and development programs. These national led efforts have also included the investment in a long list of important scientific research drilling expeditions and production test studies that have provided a wealth of information on the occurrence of methane hydrate in nature. The most notable expeditions and projects have including the following: -‐Ocean Drilling Program Leg 164 (1995) -‐Japan Nankai Trough Project (1999-‐2000) -‐Ocean Drilling Program Leg 204 (2004) -‐Japan Tokai-‐oki to Kumano-‐nada Project (2004) -‐Gulf of Mexico JIP Leg I (2005) -‐Integrated Ocean Drilling Program Expedition 311 (2005) -‐Malaysia Gumusut-‐Kakap Project (2006) -‐India NGHP Expedition 01 (2006) -‐China GMGS Expedition 01 (2007) -‐Republic of Korea UBGH Expedition 01 (2007) -‐Gulf of Mexico JIP Leg II (2009) -‐Republic of Korea UBGH Expedition 02 (2010) -‐MH-‐21 Nankai Trough Pre-‐Production Expedition (2012-‐2013) -‐Mallik Gas Hydrate Testing Projects (1998/2002/2007-‐2008) -‐Alaska Mount Elbert Stratigraphic Test Well (2007) -‐Alaska Iġnik Sikumi Methane Hydrate Production Test Well (2011-‐2012) Research coring and seismic programs carried out by the Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP), starting with the ODP Leg 164 drilling of the Blake Ridge in the Atlantic Ocean in 1995, have also contributed greatly to our understanding of the geologic controls on the formation, occurrence, and stability of gas hydrates in marine environments. For the most part methane hydrate research expeditions carried out by the ODP and IODP provided the foundation for our scientific understanding of gas hydrates. The methane hydrate research efforts under ODP-‐IODP have mostly dealt with the assessment of the geologic controls on the occurrence of gas hydrate, with a specific goal to study the role methane hydrates may play in the global carbon cycle. Over the last 10 years, national led methane hydrate research programs, along with industry interest have led to the development and execution of major methane hydrate production field test programs. Two of the most important production field testing programs have been conducted at the Mallik site in the Mackenzie River Delta of Canada and in the Eileen methane hydrate accumulation on the North Slope of Alaska. Most recently we have also seen the completion of the world’s first marine methane hydrate production test in the Nankai Trough in the offshore of Japan. Industry interest in gas hydrates has also included important projects that have dealt with the assessment of geologic hazards associated with the presence of hydrates. The scientific drilling and associated coring, logging, and borehole monitoring technologies developed in the long list of methane hydrate related field studies are one of the most important developments and contributions associated with methane hydrate research and development activities. Methane hydrate drilling has been conducted from advanced scientific drilling platforms like the JOIDES Resolution and the D/V Chikyu, which feature highly advanced integrated core laboratories and borehole logging capabilities. Hydrate research drilling has also included the use of a wide array of industry, geotechnical and multi-‐service ships. All of which have been effectively used to collect invaluable geologic and engineering data on the occurrence of methane hydrates throughout the world. Technologies designed specifically for the collection and analysis of undisturbed methane hydrate samples have included the development of a host of pressure core systems and associated specialty laboratory apparatus. The study and use of both wireline conveyed and logging-‐while-‐drilling technologies have also contributed greatly to our understanding of the in-‐situ nature of hydrate-‐bearing sediments. Recent developments in borehole instrumentation specifically designed to monitor changes associated with hydrates in nature through time or to evaluate the response of hydrate accumulations to production have also contributed greatly to our understanding of the complex nature and evolution of methane hydrate systems. Our understanding of how methane hydrates occur and behave in nature is still growing and evolving – we do not yet know if methane hydrates can be economically produced, nor do we know fully the role of hydrates as an agent of climate change or as a geologic hazard. But it is known for certain that scientific drilling has contributed greatly to our understanding of hydrates in nature and will continue to be a critical source of the information to advance our understanding of methane hydrates.

Report↗

USGS1977

Pleistocene apparent ages by U-Pb isotope and U-series methods for uranium ore in Dakota Sandstone near Gallup, New Mexico

Radiometric dates of a high-grade uranium ore from the Hogback No. 4 mine in Dakota Sandstone near Gallup, N. Mex., indicate a late Pleistocene age of mineralization. The 206 Pb/ 238 U and 207 Pb/ 235 U apparent ages of about 70 000 yr and 100000 yr, respectively, are discordant, but are in broad agreement with the discordant 230 Th/ 238 U and 231 Pa/ 235 U apparent ages of 130000 yr and 78000 yr, respectively. Although it is not clear how the analyzed sample relates to the main period of mineralization at this mine, these dates are consistent with previous age limits suggested for Dakota Sandstone uranium-ores.

New Mexico↗

USGS2002

Geologic map of the Frisco quadrangle, Summit County, Colorado

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift?partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts the northeastern corner of the quadrangle. The oldest rocks in the quadrangle underlie the Tenmile Range and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, Ogden, 1987, Rock units of the Precambrian- basement in Colorado: U.S. Geological Survey Professional Paper 1321-A, 54 p.). The oldest sedimentary unit is the Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. The sedimentary rocks are intruded by sills and dikes of dacite porphyry sills of Swan Mountain, dated at 44 Ma (Marvin, R.F., Mehnert, H.H., Naeser, C.W., and Zartman, R.E., 1989, U.S. Geological Survey radiometric ages, compilation ?C??Part five?Colorado, Montana, Utah, and Wyoming: Isochron/West, no. 53, p. 14-19. Simmons, E.C., and Hedge, C.E., 1978, Minor-element and Sr-isotope geochemistry of Tertiary stocks, Colorado mineral belt: Contributions to Mineralogy and Petrology, v. 67, p. 379-396.). Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Tertiary, on the south flank of Tenderfoot Mountain, (2) deeply weathered, very coarse gravel deposits, mostly along Gold Run and underlying Mesa Cortina; the gravels are gold bearing and were mined by hydraulic methods in the 1800's, (3) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene) that were derived from large valley glaciers that flowed down Tenmile and North Tenmile Creeks; the town of Frisco is underlain mostly by Pinedale-age glacial outwash, (4) recent landslide deposits, including one large (about 1 square kilometer) area just downslope from Lilly Pad Lake, west of I-70, and (5)extensive colluvial and alluvial deposits. The latest seismic events appear to be middle Pliestocene in age and are associated with small scarps that cut Bull Lake till but do not cut Pinedale till.

Miscellaneous Field Studies Map↗

USGS1994

Neogene and Quaternary foraminifera and paleoenvironments of a corehole from Horn Island, Mississippi

The only semipermanent surface water available on the Southern High Plains plateau of Texas and New Mexico is contained in saline lakes and in the playa lakes that form in shallow depressions, called playa basins, following heavy rainfall. The playas generally are accepted as the main source of recharge to the underlying High Plains (Ogallala) aquifer of the region, and they constitute the major wildlife habitat on the Southern High Plains. Their use as water sources, holding ponds, and waste-disposal sites by agricultural and industrial operations may potentially lead to ground-water contamination and habitat degradation. Therefore, playa lakes will play an essential role in the collection of surface-water quality and ecological data for the Southern High Plains study unit of the National Water-Quality Assessment program of the U.S. Geological Survey.

Open-File Report↗

USGS2013

Postwildfire debris-flow hazard assessment of the area burned by the 2012 Little Bear Fire, south-central New Mexico

A preliminary hazard assessment was developed of the debris-flow potential from 56 drainage basins burned by the Little Bear Fire in south-central New Mexico in June 2012. The Little Bear Fire burned approximately 179 square kilometers (km 2 ) (44,330 acres), including about 143 km2 (35,300 acres) of National Forest System lands of the Lincoln National Forest. Within the Lincoln National Forest, about 72 km 2 (17,664 acres) of the White Mountain Wilderness were burned. The burn area also included about 34 km 2 (8,500 acres) of private lands. Burn severity was high or moderate on 53 percent of the burn area. The area burned is at risk of substantial postwildfire erosion, such as that caused by debris flows and flash floods. A postwildfire debris-flow hazard assessment of the area burned by the Little Bear Fire was performed by the U.S. Geological Survey in cooperation with the U.S. Department of Agriculture Forest Service, Lincoln National Forest. A set of two empirical hazard-assessment models developed by using data from recently burned drainage basins throughout the intermountain Western United States was used to estimate the probability of debris-flow occurrence and volume of debris flows along the burn area drainage network and for selected drainage basins within the burn area. The models incorporate measures of areal burn extent and severity, topography, soils, and storm rainfall intensity to estimate the probability and volume of debris flows following the fire. Relative hazard rankings of postwildfire debris flows were produced by summing the estimated probability and volume ranking to illustrate those areas with the highest potential occurrence of debris flows with the largest volumes. The probability that a drainage basin could produce debris flows and the volume of a possible debris flow at the basin outlet were estimated for three design storms: (1) a 2-year-recurrence, 30-minute-duration rainfall of 27 millimeters (mm) (a 50 percent chance of occurrence in any given year); (2) a 10-year-recurrence, 30-minute-duration rainfall of 42 mm (a 10 percent chance of occurrence in any given year); and (3) a 25-year-recurrence, 30-minute-duration rainfall of 51 mm (a 4 percent chance of occurrence in any given year). Thirty-nine percent of the 56 drainage basins modeled have a high (greater than 80 percent) probability of debris flows in response to the 2-year design storm; 80 percent of the modeled drainage basins have a high probability of debris flows in response to the 25-year design storm. For debris-flow volume, 7 percent of the modeled drainage basins have an estimated debris-flow volume greater than 100,000 cubic meters (m 3 ) in response to the 2-year design storm; 9 percent of the drainage basins are included in the greater than 100,000 m 3 category for both the 10-year and the 25-year design storms. Drainage basins in the greater than 100,000 m 3 volume category also received the highest combined hazard ranking. The maps presented herein may be used to prioritize areas where emergency erosion mitigation or other protective measures may be needed prior to rainstorms within these drainage basins, their outlets, or areas downstream from these drainage basins within the 2- to 3-year period of vulnerability. This work is preliminary and is subject to revision. The assessment herein is provided on the condition that neither the U.S. Geological Survey nor the U.S. Government may be held liable for any damages resulting from the authorized or unauthorized use of the assessment.

New Mexico↗

USGS1999

Sea-floor images and data from multibeam surveys in San Francisco Bay, Southern California, Hawaii, the Gulf of Mexico, and Lake Tahoe, California-Nevada

Accurate base maps are a prerequisite for any geologic study, regardless of the objectives. Land-based studies commonly utilize aerial photographs, USGS 7.5-minute quadrangle maps, and satellite images as base maps. Until now, studies that involve the ocean floor have been at a disadvantage due to an almost complete lack of accurate marine base maps. Many base maps of the sea floor have been constructed over the past century but with a wide range in navigational and depth accuracies. Only in the past few years has marine surveying technology advanced far enough to produce navigational accuracy of 1 meter and depth resolutions of 50 centimeters. The Pacific Seafloor Mapping Project of the U.S. Geological Survey's, Western Coastal and Marine Geology Program, Menlo Park, California, U.S.A., in cooperation with the Ocean Mapping Group, University of New Brunswick, Fredericton, Canada, is using this new technology to systematically map the ocean floor and lakes. This type of marine surveying, called multibeam surveying, collects high-resolution bathymetric and backscatter data that can be used for various base maps, GIS coverages, and scientific visualization methods. This is an interactive CD-ROM that contains images, movies, and data of all the surveys the Pacific Seafloor Mapping Project has completed up to January 1999. The images and movies on this CD-ROM, such as shaded relief of the bathymetry, backscatter, oblique views, 3-D views, and QuickTime movies help the viewer to visualize the multibeam data. This CD-ROM also contains ARC/INFO export (.e00) files and full-resolution TIFF images of all the survey sites that can be downloaded and used in many GIS packages.

Data Series↗