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Bradford Butman

Publications and source records attributed to Bradford Butman.

At least 91 records · Page 5Linked to original sources
USGS1984

Bathymetric map of Lydonia Canyon, U.S. Atlantic Outer Continental Shelf

Lydonia Canyon is one of several large submarine canyons that indent the eastern U.S. Continental Shelf along the southern flank of Georges Bank (Index map). This bathymetric map of the upper part of Lydonia Canyon (water depths shallower than about 2,00 m) was prepared as part of a study of the physical oceanography and geology of Lydonia Canyon (Butman and others, 1983; Twichell, 1983). An accurate map of the canyon at a scale of at least 1:50,000 was needed for placement of current-meter morrings, for location of hydrographic and sediment sampling stations, and for interpretation of current-meter and geologic data. The map covers the area from 40°10'N. to 40°40'N. and from 67°28'W. to 67°50'W.

Atlantic Outer Continental Shelf, Lydonia Canyon↗
USGS1984

Long-term observations of bottom conditions and sediment movement on the Atlantic continental shelf; time-lapse photography from instrumented tripod

An instrument system that measures bottom current, temperature, light transmission, and pressure, and that photographs the bottom at 2- to 6-hour intervals has been developed to study sediment transport on the Atlantic Continental Shelf. Instruments have been deployed extensively along the United States East Coast Continental Shelf for periods of from 2 to 6 months to study the frequency, direction, and rate of bottom sediment movement, and the processes causing movement. The time-lapse photographs are used to (1) characterize the bottom benthic community and surface microtopography; (2) monitor changes in the bottom topography and near-bottom water column caused by currents and storms (for example, ripple generation and migration, sediment resuspension); and (3) monitor seasonal changes in the bottom benthic community and qualitative effects of this community on the bottom sediments.

Conference Paper↗
USGS1981

Morphology and processes associated with the accumulation of the fine-grained sediment deposit on the southern New England shelf

A 13,000 km 2 area of the southern New England Continental Shelf which is covered by anomalously fine-grained sediment has been surveyed by means of high-resolution, seismic-reflection and side-scan sonar techniques to map its morphology and structure, and a near-bottom instrument system contributed to understanding present activity of the deposit. Seismic-reflection profiles show that the fine-grained deposit, which is as much as 13 m thick, has accumulated during the last transgression because it rests on a reflector that is geomorphically similar to and continuous with the Holocene transgressive sand sheet still exposed on the shelf to the west. The ridge and swale topography comprising the sand sheet on the shelf off New Jersey and Long Island are relict in origin as these same features are found buried under the fine sediment deposit. Southwestward migrating megaripples observed on the sonographs in the eastern part of the deposit are evidence that sediment is still actively accumulating in this area. In the western part of the deposit, where surface sediment is composed of silt plus clay, evidence of present sediment mobility consists of changes in the near-bottom, suspended-matter concentrations primarily associated with storms. Nantucket Shoals and Georges Bank are thought to be the sources for the fine-textured sediment. Storms and strong tidal currents in these shoal areas may still erode available fine-grained material, which then is transported westward by the mean drift to the southern New England Shelf, where a comparatively tranquil environment permits deposition of the fine material.

Journal of Sedimentary Petrology↗
USGS1981

The Sea Data 651-4 data logger

This paper describes a digital data logger used as the primary controller and data collection device for the U.S. Geological Survey Sediment Monitoring Tripod Program. The tripods are deployed at sea in water depths up to 100 m for periods of 3 to 6 months. The system measures bottom current speed and direction, pressure, temperature, light transmission, and photographs the bottom. This report is intended to provide a description of the unit and its operation.

Open-File Report↗