Publications

To improve our understanding of the interaction of methane gas hydrate with host sediment, we studied: (1) the effects of gas hydrate and ice on acoustic velocity in different sediment types, (2) effect of different hydrate formation mechanisms on measured acoustic properties (3) dependence of shear strength on pore space contents, and (4) pore pressure effects during undrained shear. A...

A field evaluation of two new dissolved-oxygen sensing technologies, the Aanderaa Instruments AS optode model 3830 and the Sea-Bird Electronics, Inc., model SBE43, was carried out at about 32-m water depth in western Massachusetts Bay. The optode is an optical sensor that measures fluorescence quenching by oxygen molecules, while the SBE43 is a Clark polarographic membrane sensor...

A series of process-oriented numerical simulations is carried out in order to evaluate the relative role of locally generated residual flow and overtides on net sediment transport over linear sandbanks. The idealized bathymetry and forcing are similar to those present in the Norfolk Sandbanks, North Sea. The importance of bottom drag parameterization and bank orientation with respect to...

An 8500-year Holocene simulation developed in GEOMBEST provides a possible scenario to explain the evolution of barrier coast between Rodanthe and Cape Hatteras, NC. Sensitivity analyses suggest that in the Outer Banks, the rate of sea-level rise is the most important factor in determining how barrier islands evolve. The Holocene simulation provides a basis for future simulations, which...

In North Carolina, shoreline change rates are an important component of the state's coastal management program. To enhance methods of measuring shoreline change, the NC Division of Coastal Management (DCM) is considering using mean high water (MHW) shorelines extracted from lidar data together with traditional wet/dry shorelines digitized from aerial photography. To test their...

Diverse late middle Miocene dinoflagellate floras, obtained from two sites along the western edge of the Atlantic Coastal Plain in central Virginia, indicate that the eastern Virginia Piedmont was covered by marine waters about 12-13 Ma. This transgression extended farther westward across the Virginia Piedmont than any other transgression that has been documented. Extensive fluvial...

The Hudson Shelf Valley (HSV) is the largest physiographic feature on the U.S. mid-Atlantic continental shelf. The 150-km long valley is the submerged extension of the ancestral Hudson River Valley that connects to the Hudson Canyon. Unlike other incised valleys on the mid-Atlantic shelf, it has not been infilled with sediment during the Holocene. Analyses of multibeam bathymetry...

Cold seeps in deep marine settings emit fluids to the overlying ocean and are often associated with such seafloor flux indicators as chemosynthetic biota, pockmarks, and authigenic carbonate rocks. Despite evidence for spatiotemporal variability in the rate, locus, and composition of cold seep fluid emissions, the shallow subseafloor plumbing systems have never been clearly imaged in...

Thermal conductivity, thermal diffusivity and specific heat of sI methane hydrate were measured as functions of temperature and pressure using a needle probe technique. The temperature dependence was measured between −20°C and 17°C at 31.5 MPa. The pressure dependence was measured between 31.5 and 102 MPa at 14.4°C. Only weak temperature and pressure dependencies were observed. Methane...

The question of the amount of seabed to which a coastal nation is entitled is addressed in the United Nations Convention on the Law of the Sea (UNCLOS). This treaty, ratified by 153 nations and in force since 1994, specifies national obligations, rights, and jurisdiction in the oceans, and it allows nations a continental shelf out to at least 200 nautical miles or to a maritime boundary...

It is difficult and expensive to calculate changes in sediment volume for large sections of sandy beaches. Shoreline change could be a useful proxy for volume change because it can be collected quickly and relatively easily over long distances. In this paper, we summarize several studies that find a high correlation between shoreline change and subaerial volume change. We also examine...

Part of the 2006 industrial minerals review. During 2006, total U.S. gemstone trade with all countries and territories exceeded $28.3 billion. Estimates indicate that U.S. gemstone markets accounted for over 35 percent of world gemstone demand in 2006. Natural gemstone production from U.S. deposits during 2006 was worth an estimated $13.3 million, a slight decrease from 2005, and...