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At least 325 records · Page 18Linked to original sources
USGS2020

NHDPlus High Resolution (NHDPlus HR)---A hydrography framework for the Nation

Reliable and accurate high-resolution mapping of the Nation’s waters are critical inputs to models and decision support systems used to predict risk and enable response to impacts on water resources. It is necessary to know where the water is and how it relates to features beyond the stream network like forests, cities, and infrastructure. An up-to-date, high-resolution national hydrography framework is required for modeling the occurrence of water and to provide the ability to connect detailed information from the surrounding landscape to the stream network. To support this, the U.S. Geological Survey is developing NHDPlus High Resolution (NHDPlus HR), the next generation of NHDPlus using updated, high-resolution datasets to create a modern, scalable, and openly accessible hydrography framework for the inland waters of the Nation.

Fact Sheet↗
USGS1986

Recent developments in hydrologic instrumentation

The programs of the U.S. Geological Survey require instrumentation for collecting and monitoring hydrologic data in cold regions. The availability of space-age materials and implementation of modern electronics and mechanics is making possible the recent developments of hydrologic instrumentation, especially in the area of measuring streamflow under ice cover. Material developments include: synthetic-fiber sounding and tag lines; polymer (plastic) sheaves, pulleys, and sampler components; and polymer (plastic) current-meter bucket wheels. Electronic and mechanical developments include: a current-meter digitizer; a fiber-optic closure system for current-meters; non-contact water-level sensors; an adaptable hydrologic data acquisition system; a minimum data recorder; an ice rod; an ice foot; a handled sediment sampler; a light weight ice auger with improved cutter head and blades; and an ice chisel.

American Water Resources Association Technical Pub↗
USGS1995

Seafloor environments within the Boston Harbor- Massachusetts Bay sedimentary system: A regional synthesis

Modern seafloor sedimentary environments within the glaciated, topographically complex Boston Harbor and Massachusetts Bay area have been interpreted and mapped from an extensive collection of sidescan sonar records and supplemental marine geologic data. Three categories of environments are present that reflect the dominant long-term processes of erosion or nondeposition, deposition, and sediment reworking. (1) Environments of erosion or nondeposition comprise exposures of bedrock, glacial drift, coarse lag deposits, and possibly coastal plain rocks that contain sediments (where present) ranging from boulder fields to gravelly sands and occur in areas of relatively strong currents. (2) Environments of deposition contain fine-grained sediments ranging from muddy sands to muds that have accumulated in areas of predominantly weak bottom currents. (3) Environments of sediment reworking contain patches with textures ranging from sandy gravels to muds that have been produced by a combination of erosion and deposition in areas with variable bottom currents. The distribution of sedimentary environments across the Boston Harbor-Massachusetts Bay area is extremely patchy. Locally, this patchiness is due either to modifications of bottom-current strength (caused by the irregular topography and differences in water depth) or to small-scale changes in the supply of fine-grained sediments. Regional patchiness, however, reflects differences in geologic and oceanographic conditions among the estuarine, inner shelf, and basinal parts of the sedimentary system. The estuarine part of the system (Boston Harbor) is a depositional trap for fine-grained sediments because it is protected from large waves, has generally weak and variable tidal currents, and receives a large supply of fine grained detritus from natural and anthropogenic sources. The inner shelf, on the other hand, is largely an area of erosion or nondeposition due to sediment removal and redistribution during past sea-level changes, to sediment resuspension and winnowing by modern waves and currents, and to an inadequate supply of fine-grained sediments. The basinal part of the system (Stellwagen Basin) is mainly a tranquil depositional environment in which fine-grained sediments from several potential sources settle through the water column and accumulate under weak bottom currents. This study indicates areas within the Boston Harbor-Massachusetts Bay sedimentary system where fine-grained sediments and associated contaminants are likely to be either moved or deposited. It also provides a guide to the locations and variability of benthic habitats.

Massachusetts Bay↗
USGS1993

Geologic and geomorphic controls of coal development in some Tertiary Rocky Mountain basins, USA

Previous investigations have not well defined the controls on the development of minable coals in fluvial environments. This study was undertaken to provide a clearer understanding of these controls, particularly in of the lower Tertiary coal-bearing deposits of the Raton and Powder River basins in the Rocky Mountain region of the United States. In this region, large amounts of coals accumulated in swamps formed in the flow-through fluvial systems that infilled these intermontane basins. Extrabasinal and intrabasinal tectonism partly controlled the stratigraphic and facies distributions of minable coal deposits. The regional accumulation of coals was favored by the rapid basin subsidence coupled with minimal uplift of the source area. During these events, coals developed in swamps associated with anastomosed and meandering fluvial systems and alluvial fans. The extensive and high rate of sediment input from these fluvial systems promoted the formation of ombrotrophic, raised swamps, which produced low ash and anomalously thick coals. The petrology and palynology of these coals, and the paleobotany of the associated sediments, suggest that ombrotrophic, raised swamps were common in the Powder River Basin, where the climate during the early Tertiary was paratropical. The paleoecology of these swamps is identical to that of the modern ombrotrophic, raised swamps of the Baram and Mahakam Rivers of Borneo.

International Journal of Coal Geology↗
USGS1973

Deep-sea fan paleocurrent patterns of the Eocene Butano Sandstone, Santa Cruz Mountains, California

The Butano Sandstone is an Eocene continental borderland deep-sea fan deposit located in the Santa Cruz Mountains, Calif. Paleoslope measurements from contorted strata within it yield a regional northward paleoslope for the fan. Detailed paleocurrent measurements from conglomerate clast orientations, flute casts, groove casts, current-ripple markings, small-scale cross-strata, convolute laminations, and flame structures yield a sediment-dispersal pattern characterized by northward transport of coarser grained sediments downfan along major channels and transport of finer grained sediments outward and away from channels by overspilling. The overall paleocurrent pattern is oriented radially outward from the fan apex and indicates that the growth, development, and dispersal of sediments on this ancient deep-sea fan resembled that on modern deep-sea fans.

California↗
USGS2025

Fisheries research and monitoring activities of the Lake Erie Biological Station, 2024

A comprehensive understanding of fish populations and their interactions is the cornerstone of modern fishery management and the basis for Lake Erie’s Fish Community Objectives (FCOs) developed in 2020 (Francis et al. 2020). The 2024 U.S. Geological Survey (USGS) Lake Erie Biological Station Annual Report is responsive to these FCOs and the USGS obligations via a Memorandum of Understanding (MOU 2017) with the Great Lakes Fishery Commission (GLFC) Council of Lake Committees (CLC) to provide scientific information in support of fishery management. Goals for the USGS Great Lakes Deepwater Fish Assessment and Ecological Studies were to monitor long-term changes in the fish community and track population dynamics of key fishes of interest to management agencies. Specific to Lake Erie, expectations were sustained investigations of native percids, prey fish populations, and Lake Trout. All work was conducted as part of the Deepwater Science Program under the authority of the Great Lakes Fishery Research Authorization Act of 2019 (16 USC §941h). The USGS 2024 Deepwater Science Program fieldwork began in Lake Erie in March and concluded in December, using trawl, gill net, hydroacoustic, lower trophic sampling devices, and telemetry methods. This work resulted in 44 bottom trawls covering 41 ha of lake bottom and catching 48,936 fish totaling 995 kg in the West Basin of Lake Erie, with detailed results described below. Overnight gill net sets (n=25) for coldwater species were performed in the East Basin of Lake Erie. A total of 8 km of gillnet was deployed during these surveys, which caught 106 fish, 92 of which were native coldwater species: Lake Trout, Burbot, and Lake Whitefish. Results from coldwater species assessments will be reported in the Coldwater Task Group report to the GLFC and the CLC (CTG 2025). These reports are used to inform Lake Trout stocking decisions and direct lamprey control measures (16 USC §939a). USGS hydroacoustic sampling included twenty-six 5-km transects (130 km total) in the Central Basin as part of a collaborative lake-wide survey with details and results reported by the Forage Task Group (FTG 2025). Lower trophic sampling provided data from zooplankton samples (n=12) and water quality profiles (n=12) to populate a database maintained by the Michigan Department of Natural Resources (MDNR), Ontario Ministry of Natural Resources (OMNR), Ohio Department of Natural Resources (ODNR), Pennsylvania Fish and Boat Commission (PFBC), and New York State Department of Environmental Conservation (NYSDEC). USGS also assisted CLC member agencies with deployment and maintenance of Great Lakes Acoustic Telemetry Observation System (GLATOS) infrastructure throughout all three Lake Erie basins and tributaries, supporting multiple coordinated telemetry investigations. This report presents biomass-based summaries of fish communities in western Lake Erie derived from USGS bottom trawl surveys conducted from 2013 to 2024 during June and September. The survey design compliments the August ODNR- OMNRF effort by reinforcing stock assessments with more robust data. Analyses herein evaluated trends in total biomass, abundance of dominant predator and forage species, non-native species composition, biodiversity, and community structure. Data from this effort are accessible for download (Keretz et al. 2025)

Lake Erie↗
USGS2023

Geology and undiscovered resource assessment of the potash-bearing, Middle Devonian (Givetian), Prairie Evaporite, Elk Point Basin, Canada and United States

The U.S. Geological Survey (USGS) assessed undiscovered potash resources in the Elk Point Basin in Canada and the United States as part of a global mineral resource assessment. The Elk Point Basin is a large, Middle Devonian (Givetian) intracratonic evaporite basin covering approximately 1,200,000 square kilometers (km 2 ) and filled mainly with marine evaporite and minor clastic sedimentary rocks that contain stratabound potash-bearing salt. The potash-bearing salt is concentrated in four stratigraphic members (Patience Lake, Belle Plaine, White Bear, and Esterhazy) in the upper 100 meters (m) of the Prairie Evaporite and are separated by beds of halite (NaCl) that contain lesser—presently non-economic—amounts of sylvite (KCl) and carnallite (KMgCl 3 ·6H 2 O). The principal ore-bearing salt contains mainly sylvite. Four permissive tracts were defined that permit the presence of undiscovered stratabound potash (both sylvite- and carnallite-bearing salt) using geological criteria. Permissive tracts are defined by the spatial extent of each stratigraphic member that is at least 1 m thick, are less than 3 kilometers (km) from the surface, contain at least 4 percent equivalent potassium oxide (K 2 O), and contain the currently known resources. The permissive tracts include known potash deposits and potash occurrences as wells or mines not in production and show where undiscovered potash resources may be present. Well data are used to define the extent, thickness, average K 2 O equivalent grades, and volumes of each member. Data were supplied by the Saskatchewan Geological Survey or were obtained from published National Instrument (NI) 43-101 technical reports and other published reports, such as annual 10-K reports or news releases. The Elk Point Basin is the world’s largest source of potash, producing 23.0 million metric tons (Mt) of potassium chloride (KCl) (the equivalent of about 14.4 Mt of K 2 O) in 2018. In terms of global importance, the Elk Point Basin may contain 40 to greater than 50 percent of the world’s potash resources. Since 1962, potash companies have mined more than 1.5 trillion metric tons of ore containing 605 Mt of KCl (the equivalent of about 380 Mt of K 2 O). The total value of the ore produced through 2018 is on the order of $70 trillion (CAD). Potash is currently produced from eight conventional and three underground solution mines at depths ranging from 900 m to nearly 1,800 m. Estimates of the amount of potash in the Elk Point Basin vary considerably and the data and methods used in those estimations are not well documented. Known potash resources are approximately 99 billion metric tons (Bt) of ore containing 22 Bt of K 2 O equivalent. As a result of new mine openings and increased production capacity at existing mines, the total production capacity of mines in the Elk Point Basin has increased significantly (to about 32.8 Mt of KCl or 22.8 Mt of K 2 O equivalent per year). Additional production capacity of about 31 Mt of KCl (or 17 Mt of K 2 O equivalent) per year could be realized over the next decade if several current (as of 2019) exploration and development projects reach production status. Stratabound potash-bearing salt of the Prairie Evaporite presently underlies a total area of about 188,000 km 2 and has a total volume of about 2,690 cubic kilometers (km 3 ). Post-depositional solution processes considerably modified the mineralogy and presence of the potash-bearing salt. These changes had a profound effect on the volume and grade of potash resources that remained in the Prairie Evaporite and are a major consideration of exploration and mining operations as well as in this assessment of undiscovered potash resources. This USGS assessment includes the locations and possible amounts of undiscovered potash resources in the Prairie Evaporite. Volumes for each stratigraphic member were computed using member thicknesses and areal extent modified by actual, estimated geologic loss owing to salt dissolution and extraction ratios, as well as estimated distribution of carnallite and sylvite. Both sylvite- and carnallite-bearing salts were assessed for potash in this study. The assessment uses modern published grade and tonnage data. The amount of undiscovered potash is estimated by using Monte Carlo simulations to combine volume estimates of the potash-bearing members with probability distributions for average grade and bulk density. Mean potash grades (expressed as percentage of K 2 O equivalent) calculated using drill core analyses are 17.76 for the Patience Lake Member, 15.98 for the Belle Plaine Member, 10.66 for the White Bear Member, and 15.30 for the Esterhazy Member. Geologic losses reported as extraction ratios during mining may range from 27.5 to 41.6 percent and are dependent on mining method and local geologic conditions. The assessment determined that mean estimated undiscovered K 2 O equivalent resources for the Patience Lake, Belle Plaine, White Bear, and Esterhazy Members are 340, 220, 34, and 190 Bt, respectively, and estimated a total mean of 790 Bt for the entire Prairie Evaporite above a depth of 3 km. The total mineralized rock tonnage is estimated to be about 5,000 Bt. Most of the assessed potash is located within Saskatchewan with lesser amounts in Alberta and Manitoba as well as Montana and North Dakota within the United States. Although carnallite is mined for potash in Europe, it has historically been avoided in mining plans for potash-producing companies in Saskatchewan because of mining, processing, and grade considerations. Carnallite-rich salt is locally present in concentrations and volumes that could be a significant resource of magnesium chloride (MgCl 2 ) obtained as a byproduct of processing the carnallite for potash. Previously estimated reserves (not NI 43-101 compliant) of mineralized material from 1955 to 2019 are 695 Mt at 22.1 percent MgCl 2 . The total amount of K 2 O equivalent as carnallite was estimated during this USGS assessment to be about 120 Bt (or 180 Bt KCl). With uncertainties in defining the areal extent of carnallite in each of the potash-bearing members, the amount of MgCl 2 as carnallite in the Elk Point Basin could be approximately 180 Bt.

Elk Point basin↗
USGS1983

Petroleum and mineral resources of Antarctica

No known petroleum or mineral resources occur in Antarctica. The data on these subjects have been collected, mainly since the IGY (International Geophysical Year), 1957-58, as a part of other research carried out by geologists and geophysicists from a number of countries. Specific resource-related studies have not been made. Wright and Williams (1974) summarized what was known of Antarctic mineral resources a decade ago. The U.S. Geological Survey has been actively pursuing various investigations in Antarctica since 194 7. In the course of this work and that of our colleagues elsewhere in the United States and in other countries, much information relevant to petroleum and mineral resources has been obtained. Since 1976, modern state-of-the-art multichannel seismic reflection and aeromagnetic surveys by several countries over the continental margin of Antarctica have indicated thick sedimentary basins. However, no offshore drilling beneath the continental shelf has taken place since the DSDP (Deep Sea Drilling Project) holes in the Ross Sea in 1973. Geologic field investigations begun at the turn of the twentieth century have been intensified in the past two decades; most rock outcrops have been visited and samples collected. Technology to exploit resources, particularly in the Arctic, has been developing at a rapid rate, and much of it could be applied to Antarctica. As a result of the petroleum price increases of the past decade, the attention of a number of countries has turned to Antarctica, but under the policy of "voluntary restraint" adopted by the Antarctic Treaty nations, no active petroleum or mineral exploration is taking place. The Antarctic treaty countries are in the process of negotiating an Antarctic mineral resources regime that is anticipated to be completed within the next several years. Therefore it seemed timely to us to readdress the question of petroleum and mineral resources. These reports review and summarize the available information. The first report summarizes the information relevant to petroleum resources. Although uneconomic at present, petroleum is generally considered more likely to be exploited (if supergiant fields were ever found) in the next few decades than hard minerals. The second report reviews the reported occurrences of minerals in Antarctica and discusses their significance. The final report discusses the Dufek layered mafic intrusion, second only to the Bushveld Complex in size in the world; the Dufek intrusion might be considered as a potential target for mineral exploration.

Circular↗
USGS1978

Results and interpretation of exploratory drilling near the Picacho Fault, south-central Arizona

Modern surface faulting along the Picacho fault, east of Picacho, Arizona, has been attributed to ground-water withdrawal. In September 1977, three exploratory test holes were drilled 5 km east of Picacho and across the Picacho fault to investigate subsurface conditions and the mechanism of the faulting. The holes were logged by conventional geophysical and geologic methods. Piezometers were set in each hole and have been monitored since September 1977. The drilling indicates that the unconsolidated alluvium beneath the surface fault is approximately 310 m thick. Drilling and piezometer data and an associated seismic refraction survey indicate that the modern faulting is coincident with a preexisting, high-angle, normal fault that offsets units within the alluvium as well as the underlying bedrock. Piezometer and neutron log data indicate that the preexisting fault behaves as a partial ground-water barrier. Monitoring of the piezometers indicates that the magnitude of the man-induced difference in water level across the preexisting fault is seasonal in nature, essentially disappearing during periods of water-level recovery. The magnitude of the seasonal difference in water level, however, appears to be sufficient to account for the modern fault offset by localized differential compaction caused by a difference in water level across the preexisting fault. In addition, repeated level surveys since September 1977 of bench marks across the surface fault and near the piezometers have indicated fault movement that corresponds to fluctuations of water level.

Open-File Report↗
USGS2023

Spatial and temporal distribution of sinuous ridges in southeastern Terra Sabaea and the northern region of Hellas Planitia, Mars

Sinuous ridges are an important yet understudied component of Mars' hydrologic history. We have produced a map of sinuous ridges, valleys and channels, and tectonic ridges across southeastern Terra Sabaea and into northern Hellas Planitia (10°-45° S, 35°-80° E) using a CTX mosaic. Although we mapped different types of ridges and negative relief features, the focus of this paper are the sinuous ridges. We present here a new dataset of sinuous ridges that includes basic morphometry (e.g., length, width, sinuosity), morphology, and the types of terrains they are located on. We chose our region of interest because it includes surface ages spanning Mars' geologic history, with emphasis on Noachian and Hesperian terrains. The shift from either a warm and wet or a cold and icy environment to our modern cold and dry climate occurred towards the end of the Noachian and into the Hesperian, a critical temporal window to characterize fluvial landforms. Our CTX-based mapping significantly improved the documentation of fluvial landforms within the study region, with over an order of magnitude increase in the number of valley networks and channels, and nearly 1700 sinuous ridges. Sinuous ridges are found in concentrated settings, with the majority (∼80%) located within impact craters and relatively few (∼20%) on the intercrater plains. Fluvial features are prevalent on Early and Middle Noachian-aged terrain but are relatively rare in the Late Noachian, signifying a shift in fluvial activity that likely led to a decrease in channel incision and subsequent inversion of relief. A subset of sinuous ridges—radial ridges in high-elevation, degraded craters— are possible records of ancient proglacial lakes. The youngest sinuous ridges are associated with intracrater alluvial fans in a narrow zone (∼12°S to 30°S and ∼ 62°E to 77°E). These formed in the Late Hesperian into the Amazonian, reflecting a later epoch of punctuated fluvial events driven by pre-existing topography and solar insolation.

Icarus↗
USGS2024

Uncertainty and spatial correlation in station measurements for mb magnitude estimation

The body‐wave magnitude (⁠⁠) is a long‐standing network‐averaged, amplitude‐based magnitude used to estimate the magnitude of seismic sources from teleseismic observations. The U.S. Geological Survey National Earthquake Information Center (NEIC) relies on in its global real‐time earthquake monitoring mission. Although waveform modeling‐based moment magnitudes are the modern standard to characterize earthquake size, is important because (1) in many cases, waveform modeling is not possible (e.g., low signal‐to‐noise events), (2) is applicable over a broad range of magnitudes, ∼M 4–7, and (3) there is a many decades‐long history of estimating magnitudes. We use the NEIC Preliminary Determination of Epicenters earthquake catalog to investigate the uncertainty in NEIC station measurements. We show that measurements are spatially correlated, which can bias event ⁠, and we describe an empirical relation between this spatial correlation and station‐to‐station distance. We further describe an approach to mitigate bias from the spatial correlation. Accounting for the spatial covariance of observations can change the event from −0.15 to 0.07 units (10th to 90th percentile) for smaller events (⁠⁠). These smaller events have the largest standard deviations ranging from 0.05 to 0.15 units (10th to 90th percentile).

The Seismic Record↗
USGS2026

Abandonment of the Upper Devonian Greenland Gap Group and Scherr Formation and revision of the Upper Devonian Brallier and Foreknobs Formations in the central Valley and Ridge Province

This study revises the lithostratigraphic framework of the Upper Devonian interval traditionally assigned to the Greenland Gap Group across the central Appalachian Valley and Ridge Province. The work aims to modernize and standardize lithostratigraphic nomenclature, establish a new reference section and demonstrate how the revised stratigraphy improves edge-matching of 1:24,000 scale geologic maps and supports compilation mapping at scales of 1:100,000 and larger. The revision eliminates the names Greenland Gap Group, Scherr Formation and the Minnehaha Springs Member of the Scherr Formation; reassigns all strata previously designated as Scherr Formation by Dennison (1970) to the upper Brallier Formation; and abandons the basal Mallow Member of the Foreknobs Formation, placing its strata within the upper Brallier as originally defined by Butts (1918). The contact between the Brallier and Foreknobs formations is placed at the base of the first mappable, ridge-forming package of fine- to coarse-grained, cross-bedded, sandstone beds, often containing rounded quartz pebbles with minor interbeds of shale and siltstone. This contact may be gradational in places but, even in absence of good exposure, can usually be distinguished topographically in recently produced lidar-derived imagery as having elevated relief due to the presence of more resistant, compositionally mature coarse-grained sandstone-rich strata. Applying this criterion for mapping the contact between the Brallier and Foreknobs formations has resulted in reconciliation of mismatches of geologic contacts along several 7.5-minute quadrangle boundaries in the states of Virginia, West Virginia, Maryland and Pennsylvania. A new reference section at Baker, West Virginia showcases the contacts between the Harrell Shale, Brallier Formation, Foreknobs Formation and Hampshire Formation. A digital outcrop model of the reference section is provided for future preservation.

Maryland, Pennsylvania, Virginia, West Virginia↗
USGS2025

Critical Minerals in Ores (CMiO) database

Critical minerals are commodities essential to modern industrial and strategic technologies and are highly vulnerable to supply chain disruption. The Critical Minerals Mapping Initiative (CMMI) is a collaboration among the U.S. Geological Survey (USGS), the Geological Survey of Canada, and Geoscience Australia that aims to deepen global understanding of where critical minerals are located. A key output of this initiative is the Critical Minerals in Ores (CMiO) database that is advancing our collective understanding of critical minerals distributions. For instance, publicly available data on the concentrations of many critical minerals are sparse because these commodities can only be produced in small, yet essential, quantities compared to the primary commodities like copper and zinc. The CMiO database helps bridge this gap by offering high-quality, multielement geochemical data from a wide variety of critical mineral-bearing deposits around the world. Importantly, it uses a novel consensus deposit environment, group, and type classification scheme developed by the agencies that allows comparisons among ore deposits from different regions. The CMiO database contains geochemical data for more than 20,000 samples from more than 100 deposit types comprising 10 deposit environments.

Fact Sheet↗
USGS2020

Fisheries research and monitoring activities of the Lake Erie Biological Station, 2019

A comprehensive understanding of fish populations and their interactions is the cornerstone of modern fishery management and the basis for Fish Community Goals and Objectives for Lake Erie (Ryan et al. 2003). This report is responsive to U.S. Geological Survey (USGS) obligations via Memorandum of Understanding (MOU) with the Great Lakes Council of Lake Committees (CLC) to provide scientific information in support of fishery management. Goals for the USGS Great Lakes Deepwater Fish Assessment and Ecological Studies in 2019 were to monitor long-term changes in the fish community and population dynamics of key fishes of interest to management agencies. Specific to Lake Erie, expectations of this agreement were sustained investigations of native percids, forage (prey) fish populations, and Lake Trout. Our 2019 deepwater program operations began in April and concluded in December, and utilized trawl, gillnet, hydroacoustic, lower trophic sampling, and telemetry methods. This work resulted in 88 bottom trawls covering 65 ha of lake-bottom and catching 24,140 fish totaling 3,622 kg during three separate trawl surveys in the West and Central basins of Lake Erie. Overnight gillnet sets (n=44) for cold water species were performed at 42 unique locations in the West and East basins of Lake Erie. A total of 8.0 km of gillnet was deployed during these surveys, which caught 286 fish, 114 of which were native coldwater species: Lake Trout, Burbot, and Lake Whitefish. USGS hydroacoustic surveys in 2019 produced 240 km of transects, and lower trophic sampling provided data from zooplankton samples (n=21) and water quality profiles (n=21) to populate a database maintained by the Ontario Ministry of Natural Resources and Forestry (OMNRF), Ohio Division of Natural Resources (ODNR), Michigan Division of Natural Resources (MDNR), Pennsylvania Fish and Boat Commission (PFBC), and New York State Department of Environmental Conservation (NYSDEC). USGS also assisted CLC member agencies with deployment and maintenance of the Great Lakes Acoustic Telemetry Observation System (GLATOS) throughout all three Lake Erie sub-basins, supporting multiple coordinated telemetry investigations. In 2019, Lake Trout investigations included annual gill net surveys and acoustic telemetry of spawning migration and habitat use in coordination with OMNRF, NYSDEC, and PFBC. Results from Lake Trout investigations were reported in the Coldwater Task Group annual report to the Great Lakes Fishery Commission (GLFC) and the CLC (Coldwater Task Group 2020). Likewise, interagency forage fish assessments conducted with hydroacoustics were summarized and reported in the Forage Task Group annual report (Forage Task Group 2020). This report presents biomass-based summaries of fish communities in western Lake Erie derived from USGS bottom trawl surveys conducted from 2013 to 2019 during June and September. The survey design provided temporal and spatial coverage that did not exist in the historic interagency trawl database, and thus complemented the August ODNR-OMNRF effort to reinforce stock assessments with more robust data. Analyses herein evaluated trends in: total biomass, abundance of dominant predator and forage species, non-native species composition, biodiversity and community structure. Data from this effort can be explored interactively online (https://lebs.shinyapps.io/western-basin/), and are accessible for download (https://doi.org/10.5066/P9LL6YOR, Keretz et al. 2020). Annual survey data are added to these sources as the data become available.

Lake Erie↗
USGS1978

Trenches across the 1906 trace of the San Andreas Fault in northern San Mateo County, California

Two trenches were excavated across the 1906 trace of the San Andreas fault near fences that were displaced by the 1906 faulting. About 18 displacements equal to the 1906 displacement would account for the offset of a stream adjacent to one of the trenches. Review of divergent reports on the amount of fault displacement in 1906 at 7 localities indicates that right slip ranged from about 2 in (meters) to about 3 m at the main trace and was about 0.6 m on a subsidiary trace near one of the trench sites. Materials exposed in the trenches included Franciscan bedrock, Merced (?) sandstone, alluvial deposits, and modern soils. Visibility of the evidence for faulting covered a wide range. Faulting was expressed in the trenches as conspicuous color differences, abrupt termination of geologic units, fractures, gouge, granulation of rock, streaked contacts, rounding of rock fragments, and slickensides. Irregularly shaped masses of gouge and other materials found in both trenches may also be a manifestation of faulting. Neither caving of the walls nor the inflow of ground water were reliable indicators of the locations of faults in these trenches. The features exposed in the trenches clearly indicated the presence of an important zone of faults with geologically young displacements, but they were inadequate to identify with certainty the 1906 break or the probable 1838 break. For example, evidence of the 1906 rupture could not be seen in a unit 200 mm (millimeters) thick that is believed to predate 1906. The approximate location in the trenches of the 1906 zone of ruptures could, however, be inferred from surface morphology, historic records, and evidence in the trenches. A moderately sharp and steep contact between two surface soils, in itself suggestive of very young faulting, did not have a fault below it. Brass monuments were installed at the trench sites so that future surface ruptures can be related to the faults and other structures mapped in the trenches.

California↗
USGS1997

Core OL-92 from Owens Lake: Project rationale, geologic setting, drilling procedures, and summary

Several lines of evidence indicated that Owens Lake, a now-dry lake in southeast California, would probably yield a continuous and climatically informative sedimentary record. Also, the details of modern climate and runoff in the area are exceptionally well known, providing a firm basis for interpreting various types of evidence from a core in terms of past climates. Drilling was carried out in early 1992 to retrieve this record. The resulting core, OL-92, was taken from the south-central part of the lake (lat 36°22.85′ N, long 117°57.95′ W). Lake surface elevation at the drill site is 1,085 m. The core’s length is 322.86 m, recovery was ~80%, and the age of its basal sediments is ~800 ka. Study of the core has revealed lithologic, chemical, mineralogic, geophysical, and paleontologic evidence that reflects alternating periods of high- and low-volume runoff into Owens Lake. This volume presents these studies and summarizes their paleoclimatic significance.

California↗
USGS1979

Vertical crustal movements in the Charleston, South Carolina-Savannah, Georgia area

First-order vertical level surveys (National Geodetic Survey) repeated between 1955 and 1975 suggest that modern vertical crustal movements have taken place in the Atlantic Coastal Plain between Charleston, South Carolina and Savannah, Georgia. The relative sense of these movements correlates with the sense of displacement of Tertiary strata on known geologic structures. Whereas regional dip of strata in most of the Atlantic Coastal Plain is southeasterly, the regional dip of Tertiary strata in this part of the Coastal Plain averages 2 m/km to the south or southwest. Positive structural features disturb this regional dip along a poorly defined zone, about 25 km wide, parallel to the coast between Savannah and Charleston. Structural relief on these features is as much as 20 m. Repeated level lines that cross the Atlantic Coastal Plain elsewhere generally show an increase in modern relative subsidence from west to east. However, in the Charleston—Savannah area, the amount of relative subsidence remains fairly constant or decreases from west to east across the structural highs. At two localities near Charleston, where Tertiary beds are offset by faults roughly on strike with one another, an abrupt break in a repeated level line occurs where the level line crosses the probable extensions of these faults. The average modern rates of relative uplift and subsidence (assuming they are constant) are compatible with rates noted throughout the Coastal Plain. Long-term extrapolation of modern rates appears unreasonable; episodic or oscillatory movements are much more likely.

Georgia, South Carolina↗