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Geology topics

D. S. Foster

Publications and source records attributed to D. S. Foster.

At least 37 records · Page 2Linked to original sources
USGS2000

Influence of inner-continental shelf geologic framework on the evolution and behavior of the barrier-island system between Fire Island Inlet and Shinnecock Inlet, Long Island, New York

High-resolution, sea-floor mapping techniques, including sidescan-sonar and subbottom profiling, were used to investigate how the geologic framework of the inner-continental shelf influenced the Holocene evolution and modern behavior of the Fire Island barrier-island system, Long Island, New York. The inner-continental shelf off Long Island is divided into two physiographic provinces by a broad outcrop of Cretaceous coastal-plain strata offshore of Watch Hill; this outcrop was part of a subaerial headland during the Holocene marine transgression. Erosion of the headland during transgression furnished sediment to the inner-continental shelf downdrift to the west. The sediment was, in turn, reworked by oceanographic processes into a series of shoreface-attached sand ridges. The oldest (~1200 yr BP) and most stable part of the barrier-island system is immediately landward of the outcropping coastal-plain strata and thickest sand ridges. East of Watch Hill, Pleistocene sediment either is exposed on the inner-continental shelf or is buried by a veneer of modern reworked sediment. Here the barrier-island system has migrated landward at a faster rate than the segment west of Watch Hill and has been breached by numerous historic inlets. Because the Pleistocene sedimentary deposit is generally of uniform thickness throughout the study area and unconformably overlies the Cretaceous coastal-plain strata, both the Holocene and historical evolution of the Fire Island barrier-island system are controlled by the physiography of this regional unconformity. In particular, the shoreface-connected sand ridges appear to be a significant source of sediment to the western portion of Fire Island. Previous attempts to develop a sediment budget for this coastal system have failed to explain volumetric discrepancies, primarily because poor assumptions were made about the nature of sediment transport in the system. A more realistic sediment budget must include a significantly larger spatial scale, including sediment input from the inner-continental shelf.

New York↗
USGS1999

Archive of 15 cubic inch water gun data collected during USGS Cruise ALPH98013, New York Bight, 10-22, September, 1998

Background This CD-ROM contains copies of the navigation and field water gun subbottom data collected aboard the F/V Alpha & Omega II. The USGS Cruise ALPH98013 was conducted from 10-22 September, 1998, and is a collaborative involving the U.S Army Corps of Engineers, New York District and the United States Geological SurveyCoastal and Marine Geology Program, Woods Hole Field Center. In 1995, the USGS, in cooperation with the U.S Army Corps of Engineers (USACOE), New York District, began a program to generate reconnaissance maps of the sea floor offshore of the New York-New Jersey metropolitan area, one of the most populated coastal regions of the United States. The goal of this mapping program is to provide a regional synthesis of the sea-floor environment, including a description of sedimentary environments, sediment texture, sea-floor morphology, and geologic history to aid in understanding the impacts of anthropogenic activities, such as ocean dumping. This mapping effort differs from previous studies of this area by obtaining digital, sidescan sonar images that cover 100 percent of the sea floor. This investigation was motivated by the need to develop an environmentally acceptable solution for the disposal of dredged material from the New York - New Jersey Port, by the need to identify potential sources of sand for renourishment of the southern shore of Long island, and by the opportunity to develop a better understanding of the transport and long-term fate of contaminants by investigations of the present distribution of materials discharged into the New York Bight over the last 100+ years (Schwab and others, 1997). Sidescan-sonar data collected during USGS Cruises Seax95007 and Seax96004 (May 1995 and May 1996, respectively) were digitally mosaicked to provide a base suitable for use in Geographic Information Systems of the New York Bight Apex region. During USGS Cruise Alph98013, supplemental sidescan sonar and seismic reflection data were collected within the New York Bight Apex region, primarily to augment the seismic reflection portion of the mapping project. Additional sidescan sonar and seismic reflection data were collected east of the Seax95007 and Seax96004 survey areas. These data abut sidescan sonar and seismic reflection data collected off the Southern Long Island shoreline during USGS Cruises Dian96040, Dian97011, and Dian97032 (September 1996, May 1997, October 1997, respectively).

Open-File Report↗
USGS1997

Initial results of high-resolution sea-floor mapping offshore of the New York - New Jersey metropolitan area using sidescan sonar

High-resolution seismic, sidescan-sonar, multibeam bathymetry, and sediment sampling techniques were used to map the surficial geology and shallow subbottom stratigraphy of a segment of the inner shelf and nearshore region of New York-New Jersey metropolitan area. Preliminary analyses of these data provide a sedimentologic framework for addressing a wide range of science and management issues. Principal features identified include: 1) a series of sharply defined, rippled scour depressions in the nearshore areas of Long Island and New Jersey that are thought to be an erosional pattern indicative of storm-induced cross-shelf sediment-transport processes from the shoreface; 2) outcropping Upper Cretaceous to early Tertiary coastal plain strata and associated gravelly lag deposits; 3 ) morphologic and chemical indications of anthropogenic waste disposal and redistribution; 4) extensive deposits of medium- to fine-grained sand northeast and east of the Hudson Shelf Valley; 5) acoustic backscatter patterns on the sidescan imagery and sediment bedforms that indicate a general south-southwest sediment transport direction toward the Hudson Shelf Valley; and 6) the Hudson Shelf Valley is a depositional site for silty sediment and acts as a conduit for cross-shelf pollutant transport.

Northeastern Geology and Environmental Sciences↗
USGS1994

The geologic framework of southern Lake Michigan

The bathymetry is controlled by the underlying bedrock. Bedrock comprises Silurian dolomite and Devonian limestone and shale. Quaternary sediment, 10 to 40 m thick, overlies bedrock. From Waukegan, Illinois, south to Indiana Harbor, the bottom is floored by till, sand, pebbles, and cobbvles. The lake floor is erosional or nondepositional where till or gravel-cobble pavement is exposed. In contrast, north of Waukegan and east of Indiana Harbor, fine sand covers much of the bottom and grades offshore to muddy sand. The complex surficial bottom sediment distribution between Waukegan and Michigan City, Indiana, could be mapped in detail only where sidescan sonar mosaics are available. Sand, important for protecting the substrate from erosion and for maintaining beaches, is not abundant throughout much of the area. -from Authors

Illinois, Indiana, Michigan, Wisconsin↗
USGS1994

A sediment budget for southern Lake Michigan: source and sink models for different time intervals

We have constructed a sediment budget for the southern Lake Michigan basin for sand and for mud during three time periods: the past 100, 5,000, and 10,000 years. For the modern (100-year) sediment budget, accountable sediment sources add up to 93 percent of the calculated sinks. The mud budget has a source deficit of about 40%, probably due to errors in mud:sand ratios and (or) to other sources not included in our model, especially erosion of the lake floor, which accompanies bluff recession. Two terms dominate the modern sediment-budget equation: (1) bluff erosion, which is an order of magnitude larger than either rivers or aerosols as a source, and (2) deposition in the deep basin, which is more than two orders of magnitude greater as a sink than suspended sediment transport out of the basin. About half of the sand derived from bluff erosion is deposited in the deep lake; the other half must be deposited in nearshore sand bodies, beaches, and dunes. Despite the uncertainties in our estimates of sediment sources and sinks, the attempt to reconstruct sediment budgets for time intervals of 100, 5,000, and 10,000 years leads to important insights about erosion and sedimentation processes. Bluff erosion is the dominant source of both sand and mud in the basin. The deep lake floor is the primary sink for mud, whereas both the deep lake and nearshore areas are important sinks for sand. On a long-term basis, rates of bluff erosion have progressively decreased and are apparently independent of anthropogenic effects. Rates of sediment accumulation in the lake basin mirror the decrease in rates of bluff erosion for prehistoric time, but have increased markedly since human settlement, probably because of anthropogenic effects on river and aerosolic inputs.

Journal of Great Lakes Research↗