Publications

In shallow waters surface gravity waves (tides) propagate with a speed proportional to the square root of water depth (c=g(h+η)). As the ratio of free surface displacement to mean depth (η/h) approaches unity the wave will travel noticeably faster at high tide than at low tide, creating asymmetries in the tidal form. This physical process is explained analytically by the increased...

Mobile fishing gear reduces seafloor habitat complexity through the removal of structure-building fauna, e.g. emergent organisms that create pits and burrows, as well as by smoothing of sedimentary bedforms (e.g. sand ripples). In this study, we compared the relative abundance of microhabitat features (the scale at which individual fish associate with seafloor habitat) inside and outside...

This paper presents results of shear strength and acoustic velocity (p-wave) measurements performed on: (1) samples containing natural gas hydrate from the Mallik 2L-38 well, Mackenzie Delta, Northwest Territories; (2) reconstituted Ottawa sand samples containing methane gas hydrate formed in the laboratory; and (3) ice-bearing sands. These measurements show that hydrate increases shear...

Measures that describe and summarize sediment grain-size distributions are important to geologists because of the large amount of information contained in textural data sets. Statistical methods are usually employed to simplify the necessary comparisons among samples and quantify the observed differences. The two statistical methods most commonly used by sedimentologists to describe...

This report presents time-series photographs of the sea floor obtained from an instrumented tripod deployed at Site A in western Massachusetts Bay (42° 22.6' N., 70? 47.0' W., 30 m water depth, from June 1997 through June 1998. Site A is approximately 1 km south of an ocean outfall that began discharging treated sewage effluent from the Boston metropolitan area into Massachusetts Bay in...

We present new magnetostratigraphic and stable isotopic (𝜹18C, 𝜹13Ccarb) data to help improve correlations among three late Eocene impact craters and their inferred breccia and ejecta deposits. Our analyses also shed light on potential global environmental consequences attributable to the impacts. The new data come from a continuously cored interval of the subsurface Chickahominy...

Acoustic mapping of the EEZ sea floor using GLORIA side-scan sonar tool includes the margins of the continental United States, Alaska, Hawaii, and Johnston Island. This decade-long program was undertaken in cooperation with the United Kingdom's Institute of Oceanographic Sciences at the Deacon Laboratory (now the Southampton Oceanography Centre).

No abstract available.

Louisiana's barrier islands are eroding so quickly that according to some estimates they will disappear by the end of this century. Although there is little human habitation on these islands, their erosion may have a severe impact on the environment landward of the barriers. As the islands disintegrate, the vast system of sheltered wetlands along Louisiana's delta plain are exposed to...

No abstract available.

Estimating the in situ methane hydrate volume from seismic surveys requires knowledge of the rock physics relations between wave speeds and elastic moduli in hydrate/sediment mixtures. The elastic moduli of hydrate/sediment mixtures depend on the elastic properties of the individual sedimentary particles and the manner in which they are arranged. In this chapter, we present some rock...

One of the few attempts to date to map gas hydrate over a large area has been made on the Atlantic continental margin of the United States (Dillon et al., 1993, 1994, 1995). This work has resulted in the production of an extensive data base of seismic reflection lines including both single and multichannel lines, and complete GLORIA sidescan sonar coverage. This work was part of the...