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At least 1,783 records · Page 99Linked to original sources
USGS2022

Maybe so, maybe not: Canis lepophagus at Hagerman Fossil Beds National Monument, Idaho, USA

A canid dentary is described from the Pliocene Glenns Ferry Formation at Hagerman Fossil Beds National Monument, south-central Idaho, USA. The specimen possesses traits in alliance with and measurements falling within or exceeding those of Canis lepophagus . The dentary, along with a tarsal IV (cuboid) and an exploded canine come from the base of the fossiliferous Sahara complex within the monument. Improved geochronologic control provided by new tephrochronologic mapping by the U.S. Geological Survey-National Park Service Hagerman Paleontology, Environments, and Tephrochronology Project supports an interpolated age of approximately 3.9 Ma, placing it in the early Blancan North American Land Mammal Age. It is conservatively referred to herein as Canis aff. C . lepophagus with the caveat that it is an early and robust example of that species. A smaller canid, initially assigned to Canis lepophagus and then to Canis ferox , is also known from Hagerman. Most specimens of Canis ferox , including the holotype, were recently reassigned to Eucyon ferox , but specimens from the Hagerman and Rexroad faunas were left as Canis sp. and possibly attributed to C . lepophagus. We agree that these smaller canids belong in Canis and not Eucyon but reject placing them within C . lepophagus ; we refer to them here as Hagerman-Rexroad Canis . This study confirms the presence of two approximately coyote-sized canids at Hagerman and adds to the growing list of carnivorans now known from these fossil beds.

Idaho↗
USGS2005

Shelf-edge deltas and drowned barrier-island complexes on the northwest Florida outer continental shelf

A high-resolution multibeam survey of the northwest Florida shelf mapped six relict shelf-edge deltas, each with a drowned barrier-island system developed on its south and southwestern rims. The deltas appear to have formed during periods of sea-level stasis that occurred between 58,000 and 28,000 years ago. The barrier islands formed on the deltas during periods of slow regression during this same time interval. Large fields of asymmetric dunes are found on the delta surfaces as well as on the south and southwestern flanks of the deltas. The asymmetry and orientation of the dunes suggest that a northward-flowing current was sheared by the presence of the delta topography, and as a result, the upper layer of the flow continued to the north, whereas the lower layer was steered by the topography. The topographic steering accelerated the northward flow around the south and southwestern flanks with speeds adequate to form large dunes. The flow slowed after rounding southwestern flank but accelerated again as it encountered the next delta flank to the north. The age of the dune formation is unknown, and no northward-flowing geostrophic flow has been reported in the literature from this area. ?? 2004 Elsevier B.V. All rights reserved.

Geomorphology↗
USGS2012

Comparison of soil thickness in a zero-order basin in the Oregon Coast Range using a soil probe and electrical resistivity tomography

Accurate estimation of the soil thickness distribution in steepland drainage basins is essential for understanding ecosystem and subsurface response to infiltration. One important aspect of this characterization is assessing the heavy and antecedent rainfall conditions that lead to shallow landsliding. In this paper, we investigate the direct current (DC) resistivity method as a tool for quickly estimating soil thickness over a steep (33–40°) zero-order basin in the Oregon Coast Range, a landslide prone region. Point measurements throughout the basin showed bedrock depths between 0.55 and 3.2 m. Resistivity of soil and bedrock samples collected from the site was measured for degrees of saturation between 40 and 92%. Resistivity of the soil was typically higher than that of the bedrock for degrees of saturation lower than 70%. Results from the laboratory measurements and point-depth measurements were used in a numerical model to evaluate the resistivity contrast at the soil-bedrock interface. A decreasing-with-depth resistivity contrast was apparent at the interface in the modeling results. At the field site, three transects were surveyed where coincident ground truth measurements of bedrock depth were available, to test the accuracy of the method. The same decreasing-with-depth resistivity trend that was apparent in the model was also present in the survey data. The resistivity contour of between 1,000 and 2,000 Ωm that marked the top of the contrast was our interpreted bedrock depth in the survey data. Kriged depth-to-bedrock maps were created from both the field-measured ground truth obtained with a soil probe and interpreted depths from the resistivity tomography, and these were compared for accuracy graphically. Depths were interpolated as far as 16.5 m laterally from the resistivity survey lines with root mean squared error (RMSE) = 27 cm between the measured and interpreted depth at those locations. Using several transects and analysis of the subsurface material properties, the direct current (DC) resistivity method is shown to be able to delineate bedrock depth trends within the drainage basin.

Oregon↗
USGS2014

Pb-Sr-Nd-O isotopic characterization of Mesozoic rocks throughout the northern end of the Peninsular Ranges batholith: Isotopic evidence for the magmatic evolution of oceanic arc–continental margin accretion during the Late Cretaceous of southern California

Within the duration of the U.S. Geological Survey (USGS)–based Southern California Areal Mapping Project (SCAMP), many samples from the northern Peninsular Ranges batholith were studied for their whole-rock radioisotopic systematics (rubidium-strontium [Rb-Sr], uranium-thorium-lead [U-Th-Pb], and samarium-neodymium [Sm-Nd]), as well as oxygen (O), a stable isotope. The results of three main studies are presented separately, but here we combine them (>400 analyses) to produce a very complete Pb-Sr-Nd-O isotopic profile of an arc-continent collisional zone—perhaps the most complete in the world. In addition, because many of these samples have U-Pb zircon as well as argon mineral age determinations, we have good control of the timing for Pb-Sr-Nd-O isotopic variations. The ages and isotopic variations help to delineate at least four zones across the batholith from west to east—an older western zone (126–108 Ma), a transitional zone (111–93 Ma), an eastern zone (94–91 Ma), and a much younger allochthonous thrust sheet (ca. 84 Ma), which is the upper plate of the Eastern Peninsular Ranges mylonite zone. Average initial 87 Sr/ 86 Sr (Sr i ), initial 206 Pb/ 204 Pb ( 206 Pb i ), initial 208 Pb/ 204 Pb (average 208 Pb i ), initial epsilon Nd (average ε Ndi ), and δ 18 O signatures range from 0.704, 18.787, 38.445, +3.1, and 4.0‰–9.0‰, respectively, in the westernmost zone, to 0.7071, 19.199, 38.777, −5, and 9‰–12‰, respectively, in the easternmost zone. The older western zone is therefore the more chemically and isotopically juvenile, characterized mostly by values that are slightly displaced from a mantle array at ca. 115 Ma, and similar to some modern island-arc signatures. In contrast, the isotopic signatures in the eastern zones indicate significant amounts of crustal involvement in the magmatic plumbing of those plutons. These isotopic signatures confirm previously published results that interpreted the Peninsular Ranges batholith as a progressively contaminated magmatic arc. The Peninsular Ranges batholith magmatic arc was initially an oceanic arc built on Panthalassan lithosphere that eventually evolved into a continental margin magmatic arc collision zone, eventually overriding North American cratonic lithosphere. Our Pb-Sr-Nd data further suggest that the western arc rocks represent a nearshore or inboard oceanic arc, as they exhibit isotopic signatures that are more enriched than typical mid-ocean-ridge basalt (MORB). Isotopic signatures from the central zone are transitional and indicate that enriched crustal magma sources were becoming involved in the northern Peninsular Ranges batholith magmatic plumbing. As the oceanic arc–continental margin collision progressed, a mixture of oceanic mantle and continental magmatic sources transpired. Magmatic production in the northern Peninsular Ranges batholith moved eastward and continued to tap enriched crustal magmatic sources. Similar modeling has been previously proposed for two other western margin magmatic arcs, the Sierra Nevada batholith of central California and the Idaho batholith. Calculated initial Nd signatures at ca. 100 Ma for Permian–Jurassic and Proterozoic basement rocks from the nearby San Gabriel Mountains and possible source areas along the southwestern Laurentian margin of southern California, southwestern Arizona, and northern Sonora strongly suggest their involvement with deep crustal magma mixing beneath the eastern zones of the Peninsular Ranges batholith, as well as farther east in continental lithospheric zones. Last, several samples from the allochthonous, easternmost upper-plate zone, which are considerably younger (ca. 84 Ma) than any of the rocks from the northern Peninsular Ranges batholith proper, have even more enriched average Sr i , 206 Pb i , 208 Pb i , and ε Ndi signatures of 0.7079, 19.344, 38.881, and −6.6, respectively, indicative of the most-evolved magma sources in the northern Peninsular Ranges batholith and similar to radioisotopic values for rocks from the nearby Transverse Ranges, suggesting a genetic connection between the two.

Book chapter↗
USGS2011

Ontology patterns for complex topographic feature types

Complex feature types are defined as integrated relations between basic features for a shared meaning or concept. The shared semantic concept is difficult to define in commonly used geographic information systems (GIS) and remote sensing technologies. The role of spatial relations between complex feature parts was recognized in early GIS literature, but had limited representation in the feature or coverage data models of GIS. Spatial relations are more explicitly specified in semantic technology. In this paper, semantics for topographic feature ontology design patterns (ODP) are developed as data models for the representation of complex features. In the context of topographic processes, component assemblages are supported by resource systems and are found on local landscapes. The topographic ontology is organized across six thematic modules that can account for basic feature types, resource systems, and landscape types. Types of complex feature attributes include location, generative processes and physical description. Node/edge networks model standard spatial relations and relations specific to topographic science to represent complex features. To demonstrate these concepts, data from The National Map of the U. S. Geological Survey was converted and assembled into ODP.

Cartography and Geographic Information Science↗
USGS2019

Combining dynamic rupture simulations with ground motion data to characterize seismic hazard from Mw 3-5.8 earthquakes in Oklahoma and Kansas

Many seismically active areas suffer from a lack of near‐source ground‐motion recordings, making ground‐motion prediction difficult at distances within ∼ 40    km "> ∼ 40 km ∼40 km from an earthquake. We aim to aid the development of near‐source ground‐motion prediction equations (GMPEs) by generating synthetic ground‐motion data via simulation. Building on previous work using point‐source moment tensor sources to simulate small ( ⁠ M w "> M w Mw 3–4) earthquakes for a target region encompassing north central Oklahoma and south central Kansas, we perform dynamic rupture simulations of earthquakes up to M w "> M w Mw 5.8. We introduce complexity into the rupture process by adding stochastically generated heterogeneity to initial stress conditions. Our simulated ground‐motion data are added to a catalog of recorded ground‐motion data to construct a composite recorded‐simulated ground‐motion catalog that we use to develop a GMPE for the target region. This procedure can be generalized and used for GMPE development in other regions with near‐source ground‐motion data scarcity, which could directly benefit critical applications such as the National Seismic Hazard Maps produced by the U.S. Geological Survey (USGS).

Kansas, Oklahoma↗
USGS2009

Mid-Pliocene planktic foraminifer assemblage of the North Atlantic Ocean

The US Geological Survey Pliocene Research, Interpretation and Synoptic Mapping (PRISM) North Atlantic faunal data set provides a unique, temporally constrained perspective to document and evaluate the quantitative geographic distribution of key mid-Pliocene taxa. Planktic foraminifer census data from within the PRISM time slab (3.29 to 2.97 Ma) at thirteen sites in the North Atlantic Ocean have been analyzed. We have compiled Scanning Electron Micrographs for an atlas of mid-Pliocene assemblages from the North Atlantic with descriptions of each taxon to document the taxonomic concepts that accompany the PRISM data. In mid-Pliocene assemblages, the geographic distributions of extant taxa are similar to their present day distributions, although some are extended to the north. We use the distribution of extinct taxa to assess previous assumptions regarding environmental preferences.

Micropaleontology↗
USGS1987

Distribution and abundance of tidal marshes along the coast of Maine

Planimetry studies of coastal geology maps prepared by the Maine Geological Survey show that there is more than an order of magnitude more tidal marsh area in the state of Maine than documented in previously published estimates. The highly convoluted coast of Maine, which is approximately 5,970 km long, contains almost 79 km 2 of salt marsh, far more than any other New England state, New York, or the Bay of Fundy region. Reasonable estimates for the per-unit primary productivity of salt marshes lead to projections of total marsh productivity on the order of 10 10 g dry weight yr −1 for the Maine coast and 10 11 g dry weight yr −1 for the Gulf of Maine as a whole. Distribution of tidal marsh area is strongly controlled by coastal geomorphology, which varies considerably along the coast of Maine. The salt marsh area is concentrated in the southwestern coastal region of arcuate bays, where marshes have developed behind sandy beaches. A series of long islands and bedrock peninsulas in the south-central portion of the coast also provides sheltered areas where large marshes occur. Northeast of Penobscot Bay salt marshes become more numerous and smaller in average areal extent. A lack of protection from waves, along with limited sources of glacio-fluvial and glacio-marine sediments, restricts the occurrence of salt marshes in that region to the frignes of coves and tidal rivers.

Maine↗
USGS1992

An aeromagnetic survey over the northwestern Ross Ice Shelf and the McMurdo Sound area

As part of the expedition GANOVEX VI 1990/91, the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), the Alfred Wegener Institute for Polar and Marine Research (AWI), and the United States Geological Survey (USGS) carried out an airborne magnetic survey over the northwestern Ross Ice Shelf and McMurdo Sound between Ross Island, the Transantarctic Mountains, and Minna Bluff. The area planned for the aeromagnetic survey connects directly with the GANOVEX IV survey area (BGR & USGS 1987, BACHEM et al. 1989a) which terminated along an approximately cast-west line at about the latitude of Cape Bird. The GANOVEX IV survey covered the Victoria Land Basin - which is the westernmost of the three north/south striking basins in the Ross Sea - from its northern end in the Terra Nova Bay region to its known southern end at Ross Island. A possible southem extension of the Victoria Land Basin and its central graben structure (the Terror Rift as found from seismic surveys (COOPER et al. 1987) and what has been referred to as Victoria Graben in the aeromagnetic interpretation of the GANOVEX IV data (BOSUM et al. 1989) was one of the major targets for this survey. The survey was laid out in the form of blocks. A 135 km wide transect from the Transantarctic Mountains to about 175° W formed the focal block of the survey (Fig. 1) in which all major scientific objectives could be covered. Other survey blocks were planned to the south of this. During the course of the survey it turned out that in the time available no further area could be covered. Indeed, the unfavourable weather conditions made it impossible to complete even the above described main section fully. In detail, the lay-out of the survey area was closely following that of the GANOVEX IV survey to assure compatibility and direct continuation between the two data sets. The line spacing was chosen again to 4.4 km with a tic-line separation of 22 km. The survey altitude of 2,000 ft (610 m) corresponds to that of the Ross Sea section of the GANOVEX IV survey to which this survey area is directly adjacent. The profile lines were aligned approximately E-W, the tie-lines N-S. As part of the survey area is covered by the maps of the USGS Antarctica Reconnaissance Series 1:250,000 the Lambert conformal conic projection used for these maps was also used for the preparation of a flight line grid.

Polarforschung↗
USGS2018

Evaluating riparian vegetation change in canyon-bound reaches of the Colorado River using spatially extensive matched photo sets

Much of what we know about the functional ecology of aquatic and riparian ecosystems comes from work on regulated rivers (Johnson et al. 2012). What little we know about unregulated conditions on many of our larger rivers is often inferred from recollections of individuals, personal diaries, notes, maps, and collections from early scientific surveys (Webb et al. 2007) and from repeat photography (Turner and Karpiscak 1980; Webb 1996). Later surveys often included photographs typically taken at specific and relatively few locations. Because rivers and their related riparian ecosystems vary in both longitudinal and lateral dimensions, such records provide relatively general and incomplete information about historical resource conditions, especially at large spatial scales and over long spans of time.

Arizona, Colorado↗
USGS2023

Early Pliocene (Zanclean) stratigraphic framework for PRISM5/PlioMIP3 time slices

Global reconstructions of Pliocene climate provide important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. These reconstructions have been used extensively in paleoclimate modeling experiments for comparison to simulated conditions, and as boundary conditions.Most previous work focused on the Late Pliocene interval known as the mid Piacenzian Warm Period (mPWP), the interval originally identified by the U.S. Geological Survey Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM) as the PRISM interval or Mid Pliocene Warm Period. The term Mid Pliocene Warm Period is a misnomer due to changes to the geological time scale, and its use should be discontinued. The Pliocene Model Intercomparison Project (PlioMIP), now in its third phase, is expanding to include a focus on the Early Pliocene (Zanclean). PlioMIP3 experiments will allow comparison of environmental and climatic conditions before and after closure of the Central American Seaway (CAS). PlioMIP3 used the annual insolation pattern at the top of the atmosphere to determine time slices in the Zanclean that have orbital configurations that are most similar to modern. Two have been selected by PlioMIP and adopted by PRISM for inclusion in future studies: PRISM5.1 (4.474 Ma) and PRISM5.2 (4.870 Ma). Here we establish the stratigraphic framework for these Early Pliocene time slices and furnish information to help locate these intervals in proxy records of paleoenvironmental data using oxygen isotope stratigraphy, paleomagnetic stratigraphy, biostratigraphy, and biochronology (calibrated planktic foraminifer and calcareous nannofossil events).

Stratigraphy↗
USGS1991

Catalog of maps

This publication contains brief descriptions about the various types of maps made by the U.S. Geological Survey.

General Information Product↗
USGS2006

Chapter 7. The GIS project for the geologic assessment of undiscovered oil and gas in the Cotton Valley group and Travis Peak and Hosston formations, East Texas basin and Louisiana-Mississippi salt basins provinces

A geographic information system (GIS) focusing on the Upper Jurassic-Lower Cretaceous Cotton Valley Group and the Lower Cretaceous Travis Peak and Hosston Formations in the northern Gulf Coast region was developed as a visual-analysis tool for the U.S. Geological Survey's 2002 assessment of undiscovered, technically recoverable oil and natural gas resources in the East Texas Basin and Louisiana-Mississippi Salt Basins Provinces. The Central Energy Resources Team of the U.S. Geological Survey has also developed an Internet Map Service to deliver the GIS data to the public. This mapping tool utilizes information from a database about the oil and natural gas endowment of the United States-including physical locations of geologic and geographic data-and converts the data into visual layers. Portrayal and analysis of geologic features on an interactive map provide an excellent tool for understanding domestic oil and gas resources for strategic planning, formulating economic and energy policies, evaluating lands under the purview of the Federal Government, and developing sound environmental policies. Assessment results can be viewed and analyzed or downloaded from the internet web site, http://energy.cr.usgs.gov/oilgas/noga/ .

Alabama, Arkansas. Florida, Georgia, Louisiana, Mi↗
USGS2006

Chapter 4: The GIS Project for the Geologic Assessment of Undiscovered Oil and Gas in the Upper Cretaceous Navarro and Taylor Groups, Western Gulf Province, Texas

A geographic information system (GIS) focusing on the Upper Cretaceous Navarro and Taylor Groups in the Gulf Coast region was developed as a visual-analysis tool for the U.S. Geological Survey's 2003 assessment of undiscovered, technically recoverable oil and natural gas resources in the Western Gulf Province. The Central Energy Resources Team of the U.S. Geological Survey has also developed an Internet Map Service to deliver the GIS data to the general public. This mapping tool utilizes information from a database about the oil and natural gas endowment of the United States - including physical locations of geologic and geographic data - and converts the data into visual layers. Portrayal and analysis of geologic features on an interactive map provide an excellent tool for understanding domestic oil and gas resources for strategic planning, formulating economic and energy policies, evaluating lands under the purview of the Federal Government, and developing sound environmental policies. Assessment results can be viewed and analyzed or downloaded from the internet web site.

Data Series↗
USGS2026

Divisions of geologic time—Major chronostratigraphic and geochronologic units

Introduction The reports and maps of our Nation’s geological surveys inform and benefit the public, private industry, government officials, and scientists. The use of clear and consistent nomenclature and classifications can improve communication of data and interpretations. Since 1899, the U.S. Geological Survey (USGS) Geologic Names Committee (GNC) has been responsible for defining standards that promote uniform geologic nomenclature and classifications among geoscientists. The GNC periodically publishes a geologic time scale, the “Divisions of Geologic Time,” that serves as the national standard for USGS publications (for example, refer to Orndorff and others, 2023). Authors may use other published geologic time scales, such as those of the Geological Society of America (GSA) or the International Commission on Stratigraphy (ICS), provided that they are clearly specified and referenced. Access to the USGS, GSA, and ICS geologic time scales is also available from the U.S. Geologic Names Lexicon (Geolex) website https://ngmdb.usgs.gov/Geolex/stratres/timescales. The geologic time scale serves a dual purpose by enabling authors to distinguish earth material units by position (chronostratigraphic) and time (geochronologic), as outlined in order of decreasing rank.

Fact Sheet↗
USGS1892

Chattanooga Folio, Tennessee

The Geological Survey is making a large topographic map and a large geologic map of the United States, which are being issued together in the form of a Geologic Atlas. The parts of the atlas are called folios. Each folio contains a topographic map and a geologic map of a small section of country, and is accompanied by explanatory and descriptive texts. The complete atlas will comprise several thousand folios.

Folios of the Geologic Atlas↗
USGS1975

Water resources of the Cedar River watershed, southeastern Minnesota

The Cedar River Watershed Unit (as established by the states of Minnesota) consists of 1,204 square miles (3,118 square kilometres) of flat or gently undulating plain. The watershed is drained by the Cedar River and several smaller streams that flow south into Iowa and eventually into the Mississippi River. Its easternmost neck is part of a broad, flat, well-drained plain, covered by a thin sheet of glacial drift. Sinkholes have formed in the near surface carbonate bedrock, and a karst topography is developing. Farther north, along the east boundary, the drift is more than 200 feet (61 m) thick, and the land surface reaches altitudes of more than 1,450 feet (442 m) – the highest area in southeastern Minnesota. In the central part of the watershed in the southern flood plain of the Cedar River, the drift is less than 100 feet (30 m) thick, and the land surface altitude is less than 1,140 feet (347 m). The western part is dominated by a terminal moraine of the last Wisconsin glacier. Here the drift is more than 300 feet (91 m) thick, is poorly drained, and has numerous lakes. The watershed is mostly prairie and is well suited for farming, which is the dominant economic activity. Topographic quadrangle maps published by the U.S. Geological Survey are available for the entire watershed.

Minnesota↗