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USGS1985

Geologic history of Goban Spur, Northwest Europe continental margin

Drilling on Leg 80 of the Deep Sea Drilling Project-International Phase of Ocean Drilling was conducted on a transect of four sites (548-551) across the continent-ocean boundary at Goban Spur, a prominent southwest-trending structural and topographic high on the Irish continental slope. Drilling results have been integrated with physiographic, gravimetric, paleomagnetic, and seismostratigraphic data to provide a comprehensive interpretation of the geologic history of this sediment-starved passive margin. The geologic history of Goban Spur and adjacent regions may be divided into three periods: (1) a pre-rift period, beginning at the end of the Hercynian orogeny, was marked by several phases of regional faulting. From the late Paleozoic to the Triassic, a major phase was responsible for the development of northeast-trending grabens and horsts, which were especially active areas of deposition during the early and middle Mesozoic. A second phase created northwesttrending listric, normal fault systems which delineated the pre-Atlantic rift system of the Early Cretaceous. (2) A terminal period of active rifting began approximately at the Jurassic/Cretaceous boundary (late Cimmerian phase), and was marked by a regional emergence. Syn-rift deposition is recorded at Goban Spur by accumulation of a transgressive sequence of hyposaline to pelagic sediments, chiefly Barremian. Interpretation of seismic profiles indicates that (?)Aptian sequences also were deposited in the deeper half-grabens during this phase of rifting. Volcanic rocks appear to be rare or absent in the syn-rift deposits on Goban Spur. (3) The post-rifting period began when ocean crust was accreted in a trough approximately 2000 m deep, beneath what is now the Porcupine Abyssal Plain. This period was marked by the outpouring of pillows and flows of typical oceanic tholeiites, some of which were recovered at Site 550. At the same time, the seaward edge of the continental crust appears to have been deeply intruded by oceanic tholeiites, forming an intermediate crust of transitional geophysical characteristics. Post-rift sedimentation started in the early Albian, and was accompanied by continuous regional subsidence. Before the Campanian, variable depositional environments produced quite diverse sedimentary sequences in the isolated halfgrabens. Carbonaceous shales were recovered in Cenomanian strata of the deepest site (550) and in lower Turonian beds at sites of intermediate depth (549-551). Depositional environments became more uniform across the margin after the late Campanian, and sedimentation was clearly influenced by more regional or global oceanographic events. Sea-level oscillations, climatic variations, changes in bottom circulation, and vertical fluctuations of the carbonate compensation depth (CCD) were responsible for lithologic changes and major hiatuses.

Initial reports of the Deep Sea Drilling Project↗

USGS1978

Summary appraisals of the nation's ground-water resources – Mid-Atlantic region

The Mid-Atlantic Region covers a total area of about 108,000 square miles. It includes parts of Vermont, Massachusetts, New York, Pennsylvania, Maryland, West Virginia, and Virginia, the entire States of New Jersey and Delaware, and the District of Columbia. It encompasses the entire drainage basins (within the United States) of the Hudson, Delaware, Susquehanna, Potomac, and the James River and includes Long Island and the coastal drainage of New Jersey, Delaware, Maryland, and Virginia. Ground water in the region occurs in three broad types of geologic terrane: (1) unconsolidated deposits in the Coastal Plain seaward of the Fall Line; (2) hard, consolidated sedimentary rocks and crystalline igneous and metamorphic rocks in the remainder of the region; and (3) unconsolidated sand, gravel, and other deposits of glacial origin that overlie the older rocks extensively in the glaciated northern part of the region. Ground water is derived primarily from precipitation; it can be intercepted for use by pumping from wells before it reaches the streams or before it drains into coastal wetlands or the ocean. The natural discharge from the aquifers in the region is estimated to be at about 38.6 billion gallons per day; in addition, at least 140-350 trillion gallons is stored in the rocks. About 949 billion gallons of fresh ground water was withdrawn in 1970. This quantity represents about 9 percent of the total freshwater use of 10,220 billion gallons. Available ground-water reserves indicate that a considerable part of the additional supplies needed for the anticipated increase in economic activity in the region could be developed from ground water.

Delaware, Maryland, Massachusetts, New Jersey, New↗

USGS2014

Hydrogeology, hydraulic characteristics, and water-quality conditions in the surficial, Castle Hayne and Peedee aquifers of the greater New Hanover County area, North Carolina, 2012-13

A major issue facing the greater New Hanover County, North Carolina, area is the increased demand for drinking water resources as a result of rapid growth. The principal sources of freshwater supply in the greater New Hanover County area are withdrawals of surface water from the Cape Fear River and groundwater from the underlying Castle Hayne and Peedee aquifers. Industrial, mining, irrigation, and aquaculture groundwater withdrawals increasingly compete with public-supply utilities for freshwater resources. Future population growth and economic expansion will require increased dependence on high-quality sources of fresh groundwater. An evaluation of the hydrogeology and water-quality conditions in the surficial, Castle Hayne, and Peedee aquifers was conducted in New Hanover, eastern Brunswick, and southern Pender Counties, North Carolina. A hydrogeologic framework was delineated by using a description of the geologic and hydrogeologic units that compose aquifers and their confining units. Current and historic water-level, water-quality, and water-isotope data were used to approximate the present boundary between freshwater and brackish water in the study area. Water-level data collected during August–September 2012 and March 2013 in the Castle Hayne aquifer show that recharge areas with the highest groundwater altitudes are located in central New Hanover County, and the lowest are located in a discharge area along the Atlantic Ocean. Between 1964 and 2012, groundwater levels in the Castle Hayne aquifer in central New Hanover County have rebounded by about 10 feet, but in the Pages Creek area groundwater levels declined in excess of 20 feet. In the Peedee aquifer, the August–September 2012 groundwater levels were affected by industrial withdrawals in north-central New Hanover County. Groundwater levels in the Peedee aquifer declined more than 20 feet between 1964 and 2012 in northeastern New Hanover County because of increased withdrawals. Vertical gradients calculated between the Castle Hayne and Peedee aquifers at six well cluster sites were downward in August–September 2012 and March 2013 with the exception of one well pair that had a slight upward gradient in March 2013. Major ion chemistry results from samples collected in August–September 2012 from 97 well sites suggest that seawater is mixing with groundwater in both the Castle Hayne and Peedee aquifers in several locations in Brunswick, New Hanover, and Pender Counties. The 250 milligram per liter line of equal chloride concentration has moved inland in both aquifers since 1965, with the area between Futch and Pages Creeks in northeastern New Hanover County experiencing the greatest increase. Groundwater from the surficial, Castle Hayne, and Peedee aquifers had a stable isotope of water composition similar to that of modern precipitation. A comparison of chloride concentration data collected from public-supply wells in the 1960s with that collected in 2012 shows marked increases in chloride concentrations in the Peedee aquifer near the town of Carolina Beach at the southern end of New Hanover County.

North Carolina↗

USGS1980

Plan of study for the Northern Atlantic Coastal Plain Regional Aquifer System Analysis

Sediments of Cretaceous to Holocene age compose the Northern Atlantic Coastal Plain aquifer system in an area of 50,000 square miles in parts of New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina. The aquifer system is a major source of water supply in the area. About 1.4 billion gallons is withdrawn from its aquifers each day. Increasing withdrawal of ground water has created or intensified several problems such as declining water levels, development of large cones of depression, saltwater intrusion, spreading of ground-water contamination, and land subsidence. The U.S. Geological Survey has begun a comprehensive study that will define the geology, hydrology, and geochemistry of the aquifer system. The effects of future utilization of the aquifer system will be determined and alternative plans for water withdrawal will be evaluated through computer simulation modeling. This report describes the objectives, organization, and work plans of the study, and describes the work to be accomplished in each U.S. Geological Survey District of the study area.

Delaware;Maryl;New Jersey;North Carolina;Virginia↗

USGS1991

Submarine processes of the middle Atlantic continental rise based on GLORIA imagery

Approximately 6100 km of 3.5-kHz echo-sounding profiles was correlated with a GLORIA side-scan sonar image of the mid-Atlantic United States (34??N, 70??W) lower slope-upper continental rise. The image allows us to map the major erosional and depositional features and to identify major processes that have shaped the area. Interpretation of GLORIA imagery and echo-sounding profiles indicates that mass movement is the predominant process affecting sediment on the United States east coast mid-Atlantic slope and upper rise and that isobath-parallel sediment movement by geostrophic currents is restricted mainly to the lower continental rise. The mass-movement processes evident on the rise probably were most active during the Pleistocene, when sea level was lower and sediment input more active. -from Authors

Geological Society of America Bulletin↗

USGS2013

Hurricane Irene and associated floods of August 27-30, 2011, in New Jersey

Intense rainfall from Hurricane Irene during August 27–30, 2011, inundated streams throughout New Jersey resulting in peak streamflows exceeding the 100-year recurrence interval at many streamgages and causing heavy property and road damage. The rain event affected the entire State. Some notably affected areas were the Passaic and Hackensack River Basins in northeastern New Jersey with new peaks of record at 10 continuous-record streamflow-gaging stations on streams such as the Hackensack River, Ramapo River, Rockaway River, and Green Pond Brook. In the Atlantic Coastal Basin, new peaks of record were recorded at 6 continuous-record streamflow-gaging stations, 2 of which were on the Manasquan River, 1 on Toms River, 1 on the Mullica River, 1 on the North Branch Metedeconk River, and 1 on the West Branch Wading River. Several tributaries to the Delaware River, such as the Pequest River, Flat Brook, and Assunpink Creek, also experienced major flooding with new peaks of record at nine continuous-record streamflow-gaging stations. The U.S. Geological Survey (USGS) documented peak streamflows and water-surface elevations at 125 continuous-record streamflow-gaging stations, 27 crest-stage partial-record stations, and peak water-surface elevations at 24 continuous-record tide gages within the State of New Jersey. With rainfall totals averaging more than 10 inches throughout the State, peak-of-record flood elevations and streamflows occurred at 32 continuous-record streamflow-gaging stations. Flood-frequency recurrence-intervals were recomputed for 80 gages with 20 or more years of record; 25 crest-stage gages ranged from 25 years to greater than 500 years for the peak-of-record floods. The maximum peak streamflow per square mile ranged from 20 to 759 cubic feet per second per square mile. The August 27–30, 2011, flood peaks rank as the peaks of record for 32 continuous-record streamflow-gaging stations with a period of record of 23 to 100 years, as the second highest peaks for 21 continuous-record streamflow-gaging stations with a period of record of 21 to 114 years, and the third highest peaks of record for 11 continuous-record streamflow-gaging stations with a period of record of 43 to 96 years. Several gages have documented peaks dating back to 1903. About 1 million people across the State were evacuated, and every county was eventually declared a Federal disaster area. Property damage in New Jersey was estimated to be $1 billion. Governor Chris Christie declared a State of Emergency for New Jersey on August 31, 2011. After assessment of the damage by the Federal Emergency Management Agency, President Obama declared all 21 counties major disaster areas in the State of New Jersey on August 31, 2011.

New Jersey↗

USGS1996

Expanded record of Quaternary oceanographic change: Amerasian Arctic Ocean

Four sediment cores collected from the Northwind and Mendeleyev ridges, Arctic Ocean, from 1089 m to 1909 m water depth, provide an oceanographic record extending back into the Matuyama reversed polarity chron. Benthic foraminiferal analyses show four prominent assemblage zones: Bolivina arctica , Cassidulina teretis , Bulimina aculeata , and Oridorsalis tener from the upper Matuyama reversed polarity chronozone through the Brunhes normal polarity chronozone. These assemblage zones represent depth-dependent benthic foraminiferal biofacies changes associated with oceanographic events that occurred in the Amerasian basin at ∼780 and 300 ka, and indicate oceanographic influence from the North Atlantic. Recognition of these benthic assemblage zones in Arctic cores from the Alpha Ridge indicates that the benthic foraminiferal zonations in intermediate to deep water (>1000 m) Arctic cores may be more useful than preexisting lithostratigraphic zonations and should provide important information pertaining to the Quaternary paleoceanographic evolution of the Arctic Ocean.

Geology↗

USGS2020

Sediments and the sea floor of the continental shelves and coastal waters of the United States—About the usSEABED integrated sea-floor-characterization database, built with the dbSEABED processing system

Since the second half of the 20th century, there has been an increase in scientific interest, research effort, and information gathered on the geologic sedimentary character of the continental margins of the United States. Data and information from thousands of sources have increased our scientific understanding of the character of the margin surface, but rarely have those data been combined and integrated. Initially, the U.S. Geological Survey (USGS), in cooperation with the Institute of Arctic and Alpine Research at the University of Colorado Boulder, created the usSEABED database to provide surficial sea-floor-characterization data for USGS assessments of marine-based aggregates and for studies of sea-floor habitat. Since then, the USGS has continued to build up the database as a nationwide resource for many uses and applications. Previously published data derived from the usSEABED database have been released as three USGS data series publications containing data covering the U.S. Atlantic margin, the Gulf of Mexico and Caribbean regions, and the Pacific coast. An updated USGS data release unifies the three publications, incorporates additional data and sources including data from Alaska, Hawaii, and U.S. overseas territories, and provides revised output files that fix known errors and add known or inferred sampling dates. This report accompanies the data release and contains information on the methodology and products of the usSEABED database.

Open-File Report↗

USGS1968

A fossil assemblage from the wicomico formation in Berkeley County, South Carolina

Both megafossils and fossil Foraminifera have been obtained from unconsolidated sediments of the Wicomico Formation , which underlies the Penholoway terrace, a coastal feature that formed when the shoreline of the Atlantic Ocean stood about 70 feet higher than at present. Some of the fossils are Tertiary species and are assumed to have been derived from rocks of that age; the others are species commonly found in near-shore deposits of Quaternary age as well as in present-day south -Atlantic coastal waters. The Penholoway terrace in this area is shown to have been formed during a pause in marine regression from the Wicomico stand, when the sea stood near 100 feet. The relation of the Wicomico and Penholoway terraces to other coastal terraces suggests a Yarmouth age for the fossil -yielding beds.

South Carolina↗

USGS1990

Silicoflagellate and diatom biostratigraphy in successive Burdigalian transgressions, middle Atlantic coastal plain

The earliest Miocene strata on the Middle Atlantic Coastal Plain were deposited in two distinct marine transgressions separated by a hiatus in sedimentation of approximately one million years. The older unit (Bed 3A of the Calvert Formation and its correlatives) was deposited in a relatively restricted basin of middle Burdigalian (middle early Miocene) age. The younger unit (Bed 3B of the Calvert Formation and its correlatives) was deposited in a much more widespread basin of late Burdigalian (late early Miocene) age. The older deposit was completely overlapped by the younger deposit. These two beds of substantially differing geologic age are difficult, if not impossible, to distinguish solely by lithostratigraphy. They are, however, readily differentiated on the basis of their distinctive silicoflagellate and diatom assemblages.

Delaware, Maryland, New Jersey↗

USGS2010

Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Bedrock Geology

This tabular data set represents the area of bedrock geology types in square meters compiled for every catchment of MRB_E2RF1 catchments for Major River Basins (MRBs, Crawford and others, 2006). The source data set is the "Geology of the Conterminous United States at 1:2,500,000 Scale--A Digital Representation of the 1974 P.B. King and H.M. Beikman Map" (Schuben and others, 1994). The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every MRB_E2RF1 catchment for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).

Data Series↗

USGS2004

National Assessment of Shoreline Change: Part 1, Historical Shoreline Changes and Associated Coastal Land Loss Along the U.S. Gulf of Mexico

EXECUTIVE SUMMARY Beach erosion is a chronic problem along most 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 is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii and Alaska. One purpose of this work is to develop standard repeatable methods for mapping and analyzing shoreline movement so that periodic updates regarding coastal erosion and land loss can be made nationally that are systematic and internally consistent. This report on states bordering the Gulf of Mexico (Florida, Alabama, Mississippi, Louisiana, and Texas) represents the first in a series that will eventually include the Atlantic Coast, Pacific Coast, and parts of Hawaii and Alaska. The report summarizes the methods of analysis, interprets the results, provides explanations regarding the historical and present trends and rates of change, and describes how different coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical shorelines with a recent shoreline derived from lidar (Light Detection and Ranging) topographic surveys. The historical shorelines generally represent the following periods: 1800s, 1920s-1930s, and 1970s, whereas the lidar shoreline is 1998-2002. Long-term rates of change are calculated using all four shorelines (1800s to lidar shoreline), whereas short-term rates of change are calculated for the most recent period (1970s to lidar shoreline). The historical rates of change presented in this report represent past conditions and therefore are not intended for predicting future shoreline positions or rates of change. Rates of erosion for the Gulf of Mexico region are generally highest in Louisiana along barrier island and headland shores associated with the Mississippi delta. Erosion is also rapid along some barrier islands and headlands in Texas, and barrier islands in Mississippi are migrating laterally. Highest rates of erosion in Florida are generally localized around tidal inlets. The most stable Gulf beaches are along the west coast of Florida where low wave energy and frequent beach nourishment minimize erosion. Some beach segments in Texas have accreted as a result of net longshore drift convergence, and around tidal inlets that have been stabilized by long jetties. Seawalls and riprap revetments were constructed in all the Gulf Coast states as initial community responses to long-term beach erosion. Although some states, such as Florida, still permit shoreline stabilization structures, beach nourishment has become the preferred method of mitigating long-term erosion.

Open-File Report↗

USGS1977

Atlantic Margin Coring Project 1976: Preliminary Report on Shipboard and Some Laboratory Geotechnical data

This report presents reduced shipboard geotechnical data collected during the 1976 Atlantic Margin Coring Project; results of laboratory tests of specific gravity, water content, bulk density, and Atterberg limits; and sedimentation-compression e log p curves showing consolidation. A description of the procedures used at sea and in the laboratory and a short preliminary summary of the shipboard results also is included. The involvement of Marine Geotechnical Laboratory (MGL), Lehigh University, personnel in the 1976 Atlantic Margin Coring Project can be divided into two phases. In Phase One, the Lehigh nuclear-transmission densitometer was rebuilt to process cores at sea more rapidly than previously had been done in the laboratory, the equipment was assembled and tested aboard the Glomar Conception, and at-sea geotechnical measurements were made during the duration of the cruise. Data sheets were prepared for both unopened core sections (Appendix III) and split-core samples (Appendix IV). Completed data forms are on file at the MGL and at the Geological Survey in Woods Hole. Phase Two included reduction of the shipboard data, testing of all geotechnical samples taken from cores split aboard the ship, and certain other analytical work ashore utilizing the geotechnical measurements. Water content and weight/volume bulk density tests were performed at the MGL. Specific gravity and Atterberg limit tests and certain calculations were performed by Geological Survey personnel at the Corpus Christi, Texas, laboratory. During Phase One, 37 unopened, 1.5-m-long core sections were selected by Lehigh personnel for subsequent static and dynamic triaxial and consolidation testing ashore. The disposition of these cores is controlled by Geological Survey Project personnel; they are not further discussed in this report. A depth convention has been adopted in this report for the convenience of labeling core sections and analyzing the data. Each 9.2-m-long (30 ft) core liner had a maximum penetration depth referenced to the water-sediment interface; these data are given in Hathaway, et al. (1976). Each 9.2-m-long core liner was cut into six or fewer sections, each 1.5 m (5 ft) in length, aboard the ship. To the maximum penetration depth, 0.2 m was subtracted to obtain the depth at the bottom of the first 1.5 m section above the core catcher. To obtain values at the bottom of the remaining 1.5 m sections, an additional 1.5 m was added for each section. The depth of the bottom of each core section was used for all values obtained using the nuclear densitometer. Tests within core sections and samples collected from core sections were assigned depths based on the location of the test or sample within the core section. It should be clearly recognized that all depths within a 9.2-m-long core are estimates of the true depth, which cannot be uniquely calculated because of the uncertainty of the relationship of sediment contained within the core liner to true in situ depths. This report is considered to be preliminary because the author has not had access to the final lithologic logs or paleontological results, upon which a more accurate description of geotechnical results could be based. It would be inappropriate to comment on geological hazards until this information is made available.

Atlantic Ocean↗

USGS2017

Geology of the Petersburg batholith, eastern Piedmont, Virginia

The 295-300 Ma Petersburg batholith in east-central Virginia forms one of the largest and northernmost of the Alleghanian plutonic complexes in the southern Appalachian Piedmont. The batholith is primarily composed of granite including massive and foliated (both magmatic and solid-state fabrics) varieties. The plutonic complex intruded medium-grade metamorphosed volcanic/plutonic rocks of the Roanoke Rapids terrane. The western edge of the batholith experienced right lateral transpressional deformation associated with movement on the Hylas fault zone during the Alleghanian orogeny; this was followed by normal faulting and exhumation during the development of the Triassic Richmond basin. Much of the batholith was buried by a thin veneer of primarily Cenozoic siliciclastic sediments at the western edge of the Atlantic Coastal Plain. Granite rocks of the Petersburg batholith have long been quarried for both dimension and crushed stone. The purpose of this trip is to discuss the age, origin, and tectonic significance of the Petersburg batholith.

Virginia↗

USGS2010

Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Artificial Drainage (1992) and Irrigation (1997)

This tabular data set represents the estimated area of artifical drainage for the year 1992 and irrigation types for the year 1997 compiled for every MRB_E2RF1 catchment of Major River Basins (MRBs, Crawford and others, 2006). The source data sets were derived from tabular National Resource Inventory (NRI) data sets created by the National Resources Conservation Service (NRCS, U.S. Department of Agriculture, 1995, 2000). Artificial drainage is defined as subsurface drains and ditches. Irrigation types are defined as gravity and pressure. Subsurface drains are described as conduits, such as corrugated plastic tubing, tile, or pipe, installed beneath the ground surface to collect and/or convey drainage. Surface drainage field ditches are described as graded ditches for collecting excess water. Gravity irrigation source is described as irrigation delivered to the farm and/or field by canals or pipelines open to the atmosphere; and water is distributed by the force of gravity down the field by: (1) A surface irrigation system (border, basin, furrow, corrugation, wild flooding, etc.) or (2) Sub-surface irrigation pipelines or ditches. Pressure irrigation source is described as irrigation delivered to the farm and/or field in pump or elevation-induced pressure pipelines, and water is distributed across the field by: (1) Sprinkle irrigation (center pivot, linear move, traveling gun, side roll, hand move, big gun, or fixed set sprinklers), or (2) Micro irrigation (drip emitters, continuous tube bubblers, micro spray or micro sprinklers). NRI data do not include Federal lands and are thus excluded from this dataset. The tabular data for drainage were spatially apportioned to the National Land Cover Dataset (NLCD, Kerie Hitt, U.S. Geological Survey, written commun., 2005) and the tabular data for irrigation were spatially apportioned to an enhanced version of the National Land Cover Dataset (NLCDe, Nakagaki and others, 2007). The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every MRB_E2RF1 catchment for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).

Data Series↗

USGS1969

Errors in using modern stream-load data to estimate natural rates of denudation

The practice of calculating natural rates of denudation from routinely collected data on the loads of suspended and dissolved matter in modern rivers is subject to several significant errors. The sources of these errors are demonstrated by examples from the Atlantic drainage of the United States, where their total effect has apparently doubled the natural rate of erosion. The largest error is caused by assuming that modern sediment loads in populated areas represent natural erosion, whereas in fact they mainly reflect the influence of man. Conversion of forests to croplands in the middle Atlantic states causes about a tenfold increase in sediment yield. Coal mining, urbanization, and highway construction have added extra loads of sediment to the streams. Modern sediment loads in the Atlantic-draining rivers are probably 4 to 5 times greater than they would be if the area had remained undisturbed by man. Errors in calculating the chemical denudation are caused by atmospheric contributions to the dissolved loads of streams and by pollutants that are added directly to stream waters. About one-quarter of the salts in Atlantic-draining streams were contributed from the atmosphere, either as recycled sea salts or as pollutants and soil dust that originally became airborne as a result of the activities of man. Perhaps another one-tenth of the dissolved load consists of industrial and agricultural wastes or acid mine waters that have been added directly to the streams.

Connecticut, Delaware, Georgia, Maryland, Massachu↗

USGS2007

Integrated geologic and geophysical studies of North American continental intraplate seismicity

The origin of earthquakes within stable continental regions has been the subject of debate over the past thirty years. Here, we examine the correlation of North American stable continental region earthquakes using five geologic and geophysical data sets: (1) a newly compiled age-province map; (2) Bouguer gravity data; (3) aeromagnetic anomalies; (4) the tectonic stress field; and (5) crustal structure as revealed by deep seismic-reflection profiles. We find that: (1) Archean-age (3.8–2.5 Ga) North American crust is essentially aseismic, whereas post-Archean (less than 2.5 Ga) crust shows no clear correlation of crustal age and earthquake frequency or moment release; (2) seismicity is correlated with continental paleorifts; and (3) seismicity is correlated with the NE-SW structural grain of the crust of eastern North America, which in turn reflects the opening and closing of the proto– and modern Atlantic Ocean. This structural grain can be discerned as clear NE-SW lineaments in the Bouguer gravity and aeromagnetic anomaly maps. Stable continental region seismicity either: (1) follows the NE-SW lineaments; (2) is aligned at right angles to these lineaments; or (3) forms clusters at what have been termed stress concentrators (e.g., igneous intrusions and intersecting faults). Seismicity levels are very low to the west of the Grenville Front (i.e., in the Archean Superior craton). The correlation of seismicity with NE-SW–oriented lineaments implies that some stable continental region seismicity is related to the accretion and rifting processes that have formed the North American continental crust during the past 2 b.y. We further evaluate this hypothesis by correlating stable continental region seismicity with recently obtained deep seismicreflection images of the Appalachian and Grenville crust of southern Canada. These images show numerous faults that penetrate deep (40 km) into the crust. An analysis of hypocentral depths for stable continental region earthquakes shows that the frequency and moment magnitude of events are nearly uniform for the entire 0–35 km depths over which crustal earthquakes extend. This is in contradiction with the hypothesis that larger events have deeper focal depths. We conclude that the deep structure of the crust, in particular the existence of deeply penetrating faults, is the controlling parameter, rather than lateral variations in temperature, rheology, or high pore pressure. The distribution of stable continental region earthquakes in eastern North America is consistent with the existence of deeply penetrating crustal faults that have been reactivated in the present stress field. We infer that future earthquakes may occur anywhere along the geophysical lineations that we have identified. This implies that seismic hazard is more widespread in central and eastern North America than indicated by the limited known historical distribution of seismicity.

Special Paper of the Geological Society of America↗

USGS2026

Strengthening ties between the U.S. Geological Survey and Interstate Fisheries Commissions

Fish inhabiting marine coastal and Great Lakes waters of the United States forage, migrate, and reproduce without regard to human-made boundaries. In the mid-20th century, the 32 states along the U.S. coasts and Great Lakes recognized the growing need for coordinated, interjurisdictional fisheries management and formed four interstate or international fisheries commissions through federal legislation. While distinct in their authorities, each commission shares functions to support their regional partners, including coordinating fisheries science and supporting information sharing. The U.S. Geological Survey (USGS) is a federal bureau focused exclusively on science with substantial fisheries research capacity. This empowers USGS to serve as an independent broker of scientific information, which is greatly appreciated by decision-making agencies. The USGS does not maintain broad infrastructure for engaging partners across regions. Therefore, collaboration between the USGS and fisheries commissions ensures that USGS fisheries science helps address the most pressing interjurisdictional management priorities. The USGS has worked with fisheries commissions for decades to a greater or lesser extent in each of the four coastal regions: Atlantic, Pacific, Gulf, and Great Lakes. In 2020, the USGS began efforts to cohesively strengthen these partnerships across the regions. In 2024, leadership from four USGS fisheries science centers and headquarters met with the four fisheries commissions in person for the first time during the American Fisheries Society Annual Meeting. During the gathering, the new Interstate Fisheries Commissions–USGS Partnership developed coordination mechanisms and identified shared science priorities where the USGS capacity best aligns with the science needs of the commissions. Here we describe the history of collaboration between the USGS and fisheries commissions and the emerging interregional partnership.

Fisheries↗