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J. C. Hill

Publications and source records attributed to J. C. Hill.

15 recordsLinked to original sources
USGS2014

Seabed fluid expulsion along the upper slope and outer shelf of the U.S. Atlantic continental margin

Identifying the spatial distribution of seabed fluid expulsion features is crucial for understanding the substrate plumbing system of any continental margin. A 1100 km stretch of the U.S. Atlantic margin contains more than 5000 pockmarks at water depths of 120 m (shelf edge) to 700 m (upper slope), mostly updip of the contemporary gas hydrate stability zone (GHSZ). Advanced attribute analyses of high-resolution multichannel seismic reflection data reveal gas-charged sediment and probable fluid chimneys beneath pockmark fields. A series of enhanced reflectors, inferred to represent hydrate-bearing sediments, occur within the GHSZ. Differential sediment loading at the shelf edge and warming-induced gas hydrate dissociation along the upper slope are the proposed mechanisms that led to transient changes in substrate pore fluid overpressure, vertical fluid/gas migration, and pockmark formation.

Atlantic Margin↗
USGS2001

Archive of water gun subbottom data collected during USGS cruise SEAX 95007 New York Bight, 7-25, May 1995

Beginning in 1995, the USGS, in cooperation with the U.S Army Corps of Engineers (USACE), 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, seafloor 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). Data collected in 1996, USGS cruise SEAX 96004, augments data collected in 1995 with sidescan sonar and seismic reflection data collected within the New York Bight Apex region. This report is an archive of the boomer seismic reflection data collected in 1996.

New Jersey, 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↗