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At least 217 records · Page 12Linked to original sources
USGS1976

Regional geologic framework off northeastern United States

Six multichannel seismic-reflection profiles taken across the Atlantic continental margin off the northeastern United States show an excess of 14 km of presumed Mesozoic and younger sedimentary rocks in the Baltimore Canyon trough and 8 km in the Georges Bank basin. Beneath the continental rise, the sedimentary prism thickness exceeds 7 km south of New Jersey and Maryland, and it is 4.5 km thick south of Georges Bank. Stratigraphically, the continental slope–outer edge of the continental shelf is a transition zone of high-velocity sedimentary rock, probably carbonate, that covers deeply subsided basement. Acoustically, the sedimentary sequence beneath the shelf is divided into three units which are correlated speculatively with the Cenozoic, the Cretaceous, and the Jurassic-Triassic sections. These units thicken offshore, and some have increased seismic velocities farther offshore. The uppermost unit thickens from a fraction of a kilometer to slightly more than a kilometer in a seaward direction, and velocity values range from 1.7 to 2.2 km/sec. The middle unit thickens from a fraction of a kilometer to as much as 5 km (northern Baltimore Canyon trough), and seismic velocity ranges from 2.2 to 5.4 km/sec. The lowest unit thickens to a maximum of 9 km (northern Baltimore Canyon), and velocities span the 3.9 to 5.9-km/sec interval. The spatial separation of magnetic and gravity anomalies on line 2 (New Jersey) suggests that in the Baltimore Canyon region the magnetic-slope anomaly is due to edge effects and that the previously reported free-air and isostatic gravity anomalies over the outer shelf may be due in part to a lateral increase in sediment density (velocity) near the shelf edge. The East Coast magnetic anomaly and the free-air gravity high both coincide over the outer shelf edge on line 1 (Georges Bank) but are offset by 20 km from the ridge on the reflection profile. Because the magnetic-slope-anomaly wavelength is nearly 50 km across, a deep source is likely. In part, the positive free-air gravity anomaly likewise may represent the significant lateral density increase within the sedimentary section toward the outer edge of the shelf.

American Association of Petroleum Geologists Bulle↗
USGS1982

A regional assessment of potential environmental hazards to and limitations on petroleum development of the Southeastern United States Atlantic continental shelf, slope, and rise, offshore North Carolina

More than 11,000 km of high-resolution seismic-reflection data, 325 km of mid-range sidescan-sonar data, and 500 km of long-range sidescan-sonar data were examined and used to construct an environmental geology map of the Continental Shelf, Slope, and Rise for the area of the U.S. Atlantic margin between lats. 32?N. and 37?N. Hardgrounds and two faults described in previous literature also are shown on the map. On the Continental Shelf, at least two faults, the Helena Banks fault and the White Oak lineament, appear to be tectonic in origin. However, a lack of historical seismicity associated with these faults indicates that they are probably not active at the present time. Hardgrounds are widely scattered but are most abundant in Onslow Bay. Although paleostream channels are common nearshore, they do not appear to be common on the central and outer shelf except off Albemarle Sound where extensive Pleistocene, Pliocene, and late Miocene channels extend across the shelf. Mobile bottom sediments are confined mainly to the shoals off Cape Romain, Cape Fear, Cape Lookout, and Cape Hatteras. Elsewhere the sand cover is thin, and older more indurated rocks are present in subcrop. No slope-instability features were noted on the Florida-Hatteras slope off North Carolina. The lack of features indicates that this slope is relatively stable. Evidence for scour by strong currents is ubiquitous on the northern Blake Plateau although deep-water reefs are sparse. The outer edge of the plateau is dominated by a major growth fault and numerous splay and antithetic faults. These faults are the product of salt tectonism in the Carolina trough and thus are not associated with seismicity. Displacements observed near the sea floor and breached diapirs offshore indicate that the main fault is still moving. Associated with the faults are collapse features that are interpreted to be caused by karst solution and cavernous porosity in Eocene and Oligocene limestones at depth. Major slumps have taken place in two large areas of the Continental Slope. Seismic-reflection profiles of the southern area, centered on the lower slope at 1at. 33?N., long. 76?W., show a 80-m-hlgh scarp in which bedding has been truncated. Rotational slump faults are present in this area on the middle and upper slope. Sidescan images show that large blocks have slid downslope from the scarp face, furrowing the bottom. High-resolution (3.5-kHz) records show that the rotational slump faults upslope are active. The association of these slumps and the scarps with salt diapirs suggests subsidence accompanying salt tectonism as the cause. Seismic-reflection records over the northern area, at about fat. 36?20'N., long. 74?40'W., show two steep scarps, each about 225 m high on the upper and middle-slope. These slump scars and an absence of Pleistocene sediments indicate that large blocks of the slope have been removed by slumping. The slope north of fat. 35?N. is highly dissected by canyons. Mid-range sidescan-sonar records suggest that the canyons are the product of mass wasting and have probably formed largely by slumping. Sediments in a wide zone on the upper rise are highly disturbed and faulted owing to salt tectonism. Twenty-six salt diapirs are mapped, as is a zone of disturbed bottom related to salt tectonism. An area of frozen bottom (clathrate) under which shallow free gas is trapped underlies the outer Blake Plateau, the slope, and the upper rise. Although the hazards of drilling into or through clathrates have not been tested, the release of gas from beneath this frozen layer may prove to be a primary hazard to exploration.

Open-File Report↗
USGS2017

Groundwater quality in the Northern Atlantic Coastal Plain aquifer system, eastern United States

Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Northern Atlantic Coastal Plain aquifer system constitutes one of the important areas being evaluated. One or more inorganic constituents with human-health benchmarks were detected at high concentrations in about 15 percent of the study area and at moderate concentrations in about 17 percent. Organic constituents were not detected at high concentrations in the study area.

Northern Atlantic Coastal Plain↗
USGS2014

Effects of 2010 Hurricane Earl amidst geologic evidence for greater overwash at Anegada, British Virgin Islands

A post-hurricane survey of a Caribbean island affords comparisons with geologic evidence for greater overwash at the same place. This comparison, though of limited application to other places, helps calibrate coastal geology for assessment of earthquake and tsunami potential along the Antilles Subduction Zone. The surveyed island, Anegada, is 120 km south of the Puerto Rico Trench and is near the paths of hurricanes Donna (1960) and Earl (2010), which were at or near category 4 when at closest approach. The survey focused on Earl's geologic effects, related them to the surge from Hurricane Donna, and compared them further with erosional and depositional signs of southward overwash from the Atlantic Ocean that dates to 1200–1450 AD and to 1650–1800 AD. The main finding is that the geologic effects of these earlier events dwarf those of the recent hurricanes. Hurricane Earl's geologic effects at Anegada, observed mainly in 2011, were limited to wrack deposition along many of the island's shores and salt ponds, accretion of small washover (spillover) fans on the south shore, and the suspension and deposition of microbial material from interior salt ponds. Earl's most widespread deposit at Anegada, the microbial detritus, was abundantly juxtaposed with evidence for catastrophic overwash in prior centuries. The microbial detritus formed an extensive coating up to 2 cm thick that extended into breaches in beach-ridge plains of the island's north shore, onto playas that are underlain by a sand-and-shell sheet that extends as much as 1.5 km southward from the north shore, and among southward-strewn limestone boulders pendant to outcrops as much as 1 km inland. Earl's spillover fans also contrast with a sand-and-shell sheet, which was dated previously to 1650–1800, by being limited to the island's south shore and by extending inland a few tens of meters at most. These findings complement those reported in this issue by Michaela Spiske and Robert Halley (Spiske and Halley, 2014), who studied a coral-rubble ridge that lines part of Anegada's north shore. Spiske and Halley attribute the ridge to storms that were larger than Earl. But they contrast the ridge with coral boulders that were scattered hundreds of meters inland by overwash in 1200–1450.

Anegada↗
USGS2016

Geology and geomorphology of the Carolina Sandhills, Chesterfield County, South Carolina

This two-day field trip focuses on the geology and geomorphology of the Carolina Sandhills in Chesterfield County, South Carolina. This area is located in the updip portion of the U.S. Atlantic Coastal Plain province, supports an ecosystem of longleaf pine ( Pinus palustris ) and wiregrass ( Aristida stricta ), and contains three major geologic map units: (1) An ~60–120-m-thick unit of weakly consolidated sand, sandstone, mud, and gravel is mapped as the Upper Cretaceous Middendorf Formation and is interpreted as a fluvial deposit. This unit is capped by an unconformity, and displays reticulate mottling, plinthite, and other paleosol features at the unconformity. The Middendorf Formation is the largest aquifer in South Carolina. (2) A 0.3–10-m-thick unit of unconsolidated sand is mapped as the Quaternary Pinehurst Formation and is interpreted as deposits of eolian sand sheets and dunes derived via remobilization of sand from the underlying Cretaceous strata. This unit displays argillic horizons and abundant evidence of bioturbation by vegetation. (3) A <3-m-thick unit of sand, pebbly sand, sandy mud, and mud is mapped as Quaternary terrace deposits adjacent to modern drainages. In addition to the geologic units listed above, a prominent geomorphologic feature in the study area is a north-trending escarpment (incised by headwater streams) that forms a markedly asymmetric drainage divide. This drainage divide, as well as the Quaternary terraces deposits, are interpreted as evidence of landscape disequilibrium (possibly geomorphic responses to Quaternary climate changes).

South Carolina↗
USGS1980

Outer Continental Shelf oil and gas activities in the Mid-Atlantic and their onshore impacts: a summary report, November 1979

Outer continental shelf (OCS) activity in the Mid-Atlantic Region to date has been limited to exploratory drilling. The first rig began drilling in March 1978. More rigs quickly moved into the Region, and as many as nine were working at the same time for a brief period in January 1979. As of November 1979, nineteen exploratory wells and two stratigraphic test wells had been drilled by the oil companies. One of these test wells and three exploratory wells have had shows of natural gas, but none of the oil companies has yet announced that it has found enough gas to go forward with plans for production. Because of the somewhat disappointing results so far, exploratory drilling has declined. Only one company is currently operating a rig, and one other company has announced plans to begin drilling this winter. The most recent risked estimates by the U.S. Geological Survey of undiscovered, economically recoverable oil and gas resources in the Mid-Atlantic tracts currently under lease are 8 million barrels of oil and 860 billion cubic feet of natural gas. The resource estimate for oil does not represent a commercially producible quantity. On the basis of the geologic information gained from wells completed to date and the huge capital costs of building a pipeline to bring the gas ashore, the natural gas estimate for currently leased tracts in the Mid-Atlantic Region appears to be short of a commercially producible amount. To date, onshore impacts resulting from OCS exploration consist of two support bases: a helicopter base in Atlantic City, New Jersey, from which crews are flown out to the drilling rigs; and a support base in Davisville, Rhode Island, from which equipment and supplies are ferried out to the rigs by boat. It is expected that exploratory activity will remain close to present levels for at least the next six months; consequently, support activity at Davisville and Atlantic City for Mid-Atlantic OCS operations during the same period is expected to correspond to current levels.

New Jersey;Rhode Island↗
USGS2019

Geology of the Hardeeville NW Quadrangle and parts of the Brighton and Pineland Quadrangles, Jasper County, South Carolina

Introduction This publication portrays the geology of the Hardeeville NW quadrangle and parts of the Brighton and Pineland quadrangles that are within Jasper County, South Carolina. The study area is located in the Atlantic Coastal Plain province, approximately 50 to 70 kilometers (km) inland from the coast. The data are compiled from geological field mapping, light detection and ranging (lidar) elevation data, cores, optically stimulated luminescence ages, radiocarbon ages, and biostratigraphic interpretations. Most of the study area is occupied by the valley of the Savannah River, and exposures of geologic units are very limited. Traditional geologic mapping in this area is difficult because of limited access, subdued topography, extensive swamps, and abundant vegetation. The Savannah River flows predominantly southeast, and forms most of the border between the States of South Carolina and Georgia. The river is approximately 483 km long and has a total drainage area of approximately 15,850 square km. Although upstream tributaries drain the southeastern side of the Appalachian Blue Ridge province, the Savannah River begins in the Piedmont province and then flows across the Atlantic Coastal Plain province to the Atlantic Ocean. For much of its extent, the modern channel of the Savannah River is located on the southwestern side of the river valley, and the southwestern bank of the valley is the active cut bank. Within the study area, the valley of the Savannah River trends southeast and is relatively straight. The valley has relatively low relief, although the southwestern valley wall is steeper and has greater relief than the northeastern valley wall. Elevations within the valley mostly range from 3 to 15 meters (m) above sea level, whereas elevations on the high terrace that forms the eastern margin of the Savannah River valley are 15 to 20 m above sea level. The width of the valley is 6 to 7 km in the northern part of the study area and expands to 10 to 12 km farther south. The modern river channel occupies the southwestern side of the valley, and some modern (active) creeks enter the river from the west. Sand hills and low-relief terraces are present to the east of the modern river channel, and the eastern side of the valley is characterized by abandoned meandering and linear channels. Fan-shaped deposits of sand and mud are present where relict (inactive) channels enter the eastern side of the valley. Abandoned meandering channels of low relief (<3 m) are also present to the east on the high terrace (>15 m elevation) that forms the eastern margin of the Savannah River valley. Within the study area, most of the Savannah River valley is covered by alluvial wetland community vegetation dominated by cypress and tupelo trees, although sand hills within the valley are covered by xeric sand community vegetation dominated by pine trees.

South Carolina↗
USGS2009

SHRIMP U-Pb dating of recurrent Cryogenian and Late Cambrian-Early Ordovician alkalic magmatism in central Idaho: Implications for Rodinian rift tectonics

Composite alkalic plutonic suites and tuffaceous diamictite, although discontinuously exposed across central Idaho in roof pendants and inliers within the Idaho batholith and Challis volcanic-plutonic complex, define the >200-km-long northwest-aligned Big Creek-Beaverhead belt. Sensitive highresolution ion microprobe (SHRIMP) U-Pb zircon dates on these igneous rocks provide direct evidence for the orientation and location of the Neoproterozoic-Paleozoic western Laurentian rift margin in the northern U.S. Cordillera. Dating delimits two discrete magmatic pulses at ca. 665-650 Ma and 500-485 Ma at the western and eastern ends, respectively, of this belt. Together with the nearby 685 Ma volcanic rocks of the Edwardsburg Formation, there is a 200 Ma history of recurrent extensional magmatic pulses along the belt. A similar history of recurrent uplift is reflected in the stratigraphic record of the associated miogeoclinal and cratonal platform basins, suggesting that the Big Creek-Beaverhead belt originated as a border fault during continental rift events. The magmatic belt is paired with the recurrently emergent Lemhi Arch and narrow miogeoclinal facies belts and it lies inboard of a northwest-striking narrow zone of thinned continental crust. These features define a northeast-extending upper-plate extensional system between southeast Washington and southeast Idaho that formed a segment of the Neoproterozoic-Paleozoic miogeocline. This segment was flanked on the north by the St. Mary-Moyie transform zone (south of a narrow southern Canadian upper-plate margin) and on the south by the Snake River transfer zone (north of a broad Great Basin lower-plate margin). These are the central segments of a zigzagshaped Cordilleran rift system of alternating northwest-striking extensional zones offset by northeast-striking transfers and transforms. The data substantiate polyphase rift and continental separation events that included (1) pre-and syn-Windermere rifting, (2) Windermere margin subsidence, (3) late Ediacaran-Cambrain rifting, and (4) welldeveloped late Ediacaran-Devonian passive margin subsidence and deposition. Timing and geometries support synchronous but opposing divergence along Cordilleran and Atlantic rifts with a junction in Southern California-Sonora. ?? 2010 Geological Society of America.

Geological Society of America Bulletin↗
USGS2013

Archive of post-Hurricane Isabel coastal oblique aerial photographs collected during U.S. Geological Survey Field Activity 03CCH01 from Ocean City, Maryland, to Fort Caswell, North Carolina and Inland from Waynesboro to Redwood, Virginia, September 21 - 23, 2003

On September 21 - 23, 2003, the United States Geological Survey (USGS) conducted an oblique aerial photographic survey along the Atlantic coast from Ocean City, Md., to Fort Caswell, N.C., and inland oblique aerial photographic survey from Waynesboro to Redwood, Va., aboard a Navajo Piper twin-engine airplane. The coastal survey was conducted at an altitude of 500 feet (ft) and approximately 1,000 ft offshore. For the inland photos, the aircraft tried to stay approximately 500 ft above the terrain. These coastal photos were used to document coastal changes like beach erosion and overwash caused by Hurricane Isabel, while the inland photos looked for potential landslides caused by heavy rains. The photos may also be used as baseline data for future coastal change analysis. The USGS and the National Aeronautics and Space Administration (NASA) surveyed the impact zone of Hurricane Isabel to better understand the changes in vulnerability of the Nation’s coasts to extreme storms (Morgan, 2009). This report serves as an archive of photographs collected during the September 21 - 23, 2003, post-Hurricane Isabel coastal and inland oblique aerial survey along with associated survey maps, KML files, navigation files, digital Field Activity Collection System (FACS) logs, and Federal Geographic Data Committee (FGDC) metadata. Refer to the Acronyms page for expansions of all acronyms and abbreviations used in this report. The USGS St. Petersburg Coastal and Marine Science Center (SPCMSC) assigns a unique identifier to each cruise or field activity. For example, 03CCH01 tells us the data were collected in 2003 for the Coastal Change Hazards (CCH) study and the data were collected during the first field activity for that project in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the ID number. The photographs provided here are Joint Photographic Experts Group (JPEG) scanned images of the analog 35 millimeter (mm) color positive slides. The photograph locations are estimates of the location of the plane (see the Navigation page). The metadata values for photo creation time, GPS latitude, GPS longitude, GPS position (latitude and longitude), keywords, credit, artist, caption, copyright, and contact were added to each photograph's EXIF header using EXIFtool (Subino and others, 2012). Photographs can be opened directly with any JPEG-compatible image viewer by clicking on a thumbnail on the contact sheet, or, when viewing the Google Earth KML file, by clicking on the marker and then clicking on either the thumbnail or the link below the thumbnail. Nathaniel Plant (USGS - St. Petersburg, Fla.), and Ann Marie Ascough (formerly contracted at the USGS - St. Petersburg, Fla.) helped with the creation of KML files. To view the photos and survey maps, proceed to the Photos and Maps page.

Maryland, North Carolina, Virginia↗
USGS1986

Free-air gravity anomaly map of the Long Island Platform

The U.S. Geological Survey (USGS) has collected marine gravity data along the U.S. Atlantic continental margin during the last decade. This map of the Long Island platform combines the data used to make the preliminary free-air gravity anomaly map of the Atlantic continental margin (Grow and others, 1976) with the new gravity values collected aboard the RV Gilliss in 1979 and the RV Gyre in 1981. Carl Bowin provided the USNS Kealthley data from the Woods Hole Oceanographic Institution gravity data-base. We thank Bab Bowles (USGS) for his advice on editing the navigation and gravity data.

Long Island↗
USGS2022

U.S. Geological Survey coastal plain amplification virtual workshop

In early October of 2020, the U.S. Geological Survey (USGS) held a virtual workshop to discuss Gulf and Atlantic Coastal Plains site-response models. Earthquake researchers came together to assess (1) research related to proposed Coastal Plains amplification models and (2) USGS plans for implementing these models. Presentations spanned a broad range of topics from Atlantic and Gulf Coastal Plains geophysical properties including seismic velocity and attenuation, to ground motion amplification models and their impacts on seismic hazard. Interspersed with these presentations were discussions regarding the definition and extent of the Atlantic and Gulf Coastal Plains, potential complexities of wave propagation in the Atlantic and Gulf Coastal Plains, and problems that need to be overcome to implement various proposed site-response models. Based on feedback from this workshop, the USGS working group on Coastal Plain Amplification is considering applying published models that depend on sediment thickness. The working group is also exploring potential application of models that depend on the length of path traversed across the Coastal Plain, including the Gulf Coastal Plain ground-motion model adjustments from the Next Generation Attenuation Relationships for the Eastern United States.

Gulf and Atlantic Coast Plains↗
USGS1970

Streamflow from the United States into the Atlantic Ocean during 1931-1960

Streamflow from the United States into the Atlantic Ocean, between the international stream St. Croix River, inclusive, and Cape Sable, Fla., averaged about 355,000 cfs (cubic feet per second) during the 30-year period 1931-60, or roughly 20 percent of the water that, on the average flows out of the conterminous United States. The area drained by streams flowing into the Atlantic Ocean is about 288,000 square miles, including the Canadian part of the St. Croix and Connecticut River basins, or a little less than 10 percent of the area of the conterminous United States. Hence, the average streamflow into the Atlantic Ocean, in terms of cubic feet per second per square mile, is about twice the national average of the flow that leaves the conterminous United States. Flow from about three-fourths of the area draining into the Atlantic Ocean is gaged at streamflow measuring stations of the U.S. Geological Survey. The remaining one-fourth of the drainage area consists mostly of low-lying coastal areas from which the flow was estimated, largely on the basis of nearby gaging stations. Streamflow, in terms of cubic feet per second per square mile, decreases rather progressively from north to south. It averages nearly 2 cfs along the Maine coast, about 1 cfs along the North Carolina coast, and about 0.9 cfs along the Florida coast.

Water Supply Paper↗
USGS1987

Passive margins: U.S. Geological Survey Line 19 across the Georges Bank basin

Georges Bank is a shallow part of the Atlantic continental shelf southeast of New England (Emery and Uchupi, 1972, 1984). This bank, however, is merely the upper surface of several sedimentary basins overlying a block-faulted basement of igneous and metamorphic crystalline rock. Sedimentary rock forms a seaward-thickening cover that has accumulated in one main depocenter and several ancillary depressions, adjacent to shallow basement platforms of paleozoic and older crystalline rock. Georges Bank basin contains a thickness of sedimentary rock greater than 10 km, whereas the basement platforms that flank the basin are areas of thin sediment accumulation (less than 5 km).

AAPG Studies in Geology↗
USGS1964

Geology and ground-water resources of southeastern New Hampshire

The continued growth and development of southeastern New Hampshire, an area of about 390 square miles adjacent to the Atlantic Ocean, will depend partly on effectively satisfying the demand for water, which has increased rapidly since World War II. The report identifies and describes the principal geologic units with respect to the occurrence of ground water. These units include bedrock and the various unconsolidated deposits that mantle the bedrock surface discontinuously throughout the area. The bedrock formations, consisting of igneous and metamorphic rocks, chiefly of Paleozoic age, form a single water-bearing unit. Ground water is in joints and fractures. The fractures are small and scattered and therefore impart only a low permeability to the rocks. Wells in the bedrock commonly produce small but reliable supplies of ground water at depths of less than 150 feet. The yields of about 80 wells inventoried for this report ranged from 1? to 100 gpm (gallons per minute) and the median was 912 gpm. Depths ranged from 45 to 600 feet. The unconsolidated deposits consist of glacial drift of Pleistocene age; swamp deposits, alluvium, and beach deposits of Recent age; and eolian deposits of Pleistocene -and Recent age. For this report the glacial drift is divided into till, ice-contact deposits, marine deposits, and outwash and shore deposits. Glacial till forms a discontinuous blanket, commonly less than 15 but in some hills (drumlins) as much as about 200 feet thick. It has a low permeability but, because of its widespread outcrop area, it has been utilized as a source of water for numerous domestic supplies. Because most wells in till are shallow, many fail to meet modern demands during dry summers. Ice-contact deposits locally form kames, kame terraces, kame plains, and ice-channel fillings throughout the area. They overlie bedrock and till and range in thickness from less than 1 foot to as much as 190 feet. In general, the ice-contact deposits are coarse textured and permeable, but variations in- the physical and hydrologic properties of a single deposit and from deposit to deposit are common. Ice-contact deposits are the source of the larger ground-water supplies in southeastern New Hampshire. Marine deposits underlie lowlands and valleys to a distance of about 20 miles inland from the present coastline. They commonly overlie bedrock and till and at places overlie or are interbedded with ice-contact deposits. Marine deposits range in thickness from less than 1 foot to possibly 75 feet. They are fine textured and impermeable; they do not yield water to wells in southeastern New Hampshire but generally act as a barrier to ground-water movement. Outwash and shore deposits form broad sand plains or gently sloping terraces of small extent. At most places the outwash and shore deposits, which range in thickness from less than 1 foot to about 50 feet, overlie marine deposits, but at some places they overlie bedrock, till, or ice-contact deposits. The outwash and shore deposits are fine textured and moderately permeable. They commonly yield enough ground water to meet the needs of farms, homes, and small industries. Alluvium underlies the flood plains and channels of the principal streams and overlies bedrock and older unconsolidated deposits wherever streams cross the older units. The alluvium generally is not tapped by wells. Beach deposits occupy areas along the Atlantic Ocean between promontories of bedrock or till. In general beach deposits are permeable and are a source of water supplies for domestic use. Yields of wells are limited, however, by the danger of drawing in salty water. Recharge in southeastern New Hampshire is derived principally from precipitation on outcrop areas of ice-contact deposits and outwash and shore deposits during the nongrowing season. Ground water is discharged naturally by springs, by effluent seepage to streams and other bodies of surface water, and by evapotranspiration. It

Water Supply Paper↗
USGS2011

Surficial geology and benthic habitat of the German Bank seabed, Scotian Shelf, Canada

To provide the scientific context for management of a newly opened scallop fishing ground, surficial geology and benthic habitats were mapped on German Bank on the southern Scotian Shelf off Atlantic Canada. To provide a seamless regional dataset, multibeam sonar surveys covered 5320 sqaure kilometres of the bank in water depths of 30–250 m and provided 5 m horizontal resolution bathymetry and backscatter strength. Geoscience data included high-resolution geophysical profiles (seismic reflection and sidescan sonar) and seabed sediment samples. Geological interpretation and is overlain in places by glacial and postglacial sediment. Biological data included seafloor video transects and photographs from which 127 taxa of visible megabenthos were identified. Trawl bycatch data were obtained from government annual research surveys. Statistical analysis of revealed that bedrock is exposed at the seafloor on much of German Bankthese two datasets and a suite of oceanographic environmental variables demonstrated that significantly different fauna exist on bedrock, glacial sediment and postglacial sediment.

German Bank seabed, Scotian Shelf↗
USGS2005

Evidence of cold climate slope processes from the New Jersey Coastal Plain: Debris flow stratigraphy at Haines Corner, Camden County, New Jersey

Excavations through surficial deposits across the New Jersey Coastal Plain commonly reveal homogenized surficial sediments, deformed sedimentary structures, chaotically rearranged bed-forms, and wedge-shaped cracks filled with sand from the top-most layers of extant soil profiles. As a whole, these abundant, broadly distributed phenomena are best explained as artifacts of an era of frozen ground during the last Pleistocene glacial maximum. Vigorous freeze-thaw processes and abundant seasonal rainfall created a landscape of low relief covered by highly mobile surficial deposits. The surficial deposits are at grade into broad, flat bottomed valleys now drained by small, tightly meandering, under-fit streams. Modern fluvial, aeolian, and slope processes are ineffectual in either creating or modifying these landscapes. One particularly brief exposure of complex slope deposits was documented at Haines Corner, Camden County, during the field work (1986) for the Surficial Geologic Map of southern and central New Jersey. The exposure, now presented and interpreted here, provides previously unavailable details of a system of freeze-thaw driven processes that unfolded upon a frozen, impermeable substrate 80 miles south of the southern margin of the Wisconsinan glacial advance to Long Island, N.Y. At the time of these extreme processes, the presently sub-aerial New Jersey Coastal Plain was not proximal to moderating effects of the Atlantic Ocean, being about 100 miles inland and 300 feet above the lowered sea level. Current studies of analogous deposits across the mid-Atlantic Coastal Plain now benefit from dating techniques that were not available during the geologic mapping field work (1985-'92). During the mapping in New Jersey, hundreds of exposures failed to produce datable carbon remains within the stratigraphy of the surficial deposits. Recently reported TL dates from wind-blown sand filling frost wedges, exposed elsewhere in New Jersey, indicate that the widely distributed surficial deposits of the New Jersey Coastal Plain were active during the maximum cold period of the late Pleistocene (around 18,000 years ago).

New Jersey↗
USGS1997

Geophysical database of the east coast of the United States; southern Atlantic margin, stratigraphy and velocity in map grids

In 1990, the Naval Oceanographic Office and the U.S. Geological Survey agreed to develop a digital data base of stratigraphy and acoustic properties of sediments along the U.S. East Coast of the United States. The objective of this work was to utilize more than 25,000 km of publicly available multichannel seismic-reflection profiles (Sheridan et al., 1988) in order to assign acoustic properties to the continental margin postrift sediments in an internally consistent, geologically meaningful, regionally extensive, digital form. The acoustic properties of interest include thickness, depth, compressional- and shear-wave velocity, compressional- and shear-wave attenuation, density, and lithology. This data base subdivides the 0- to 14-km thick Jurassic and younger postrift deposits into 18 mappable horizons. The spatial scale of gridding is 5' latitude by 5 ' longitude, or about 9x8 km. This report describes the second part of developing the data base for the continental margin between Florida and Cape Hatteras: spatial gridding of the digital stratigraphic and velocity data, derivative calculations of density, shear-wave velocity, and attenuation, and construction of the final data base. The first report (Hutchinson et al., 1995) describes how the stratigraphy and velocity were digitized from the original profiles. Complementary reports that describe the data base for the area between Cape Hatteras and Georges Bank are given in Klitgord and Schneider (1994) and Klitgord et al. (1994).

Open-File Report↗