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Second Quarter Cuise News: R/V G.K. Gilbert

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4/22-5/5: Transited from St. Petersburg to St. Augustine to study the flow characteristics, bathymetry, and sub-bottom profile of a "fresh"-water spring located 2 1/2 miles off the coast of Crescent Beach, FL. The spring is emanating from a depression ~130 ft deep that is located in surrounding water depths of ~65 ft. Divers experienced a complete lack of visibility and could sense only a little flow, although a sulfide-smelling boil was apparent on the surface. A pumped-CTD cast indicated a minimum salinity of about 6 PSU at depth. A sidescan survey around the spring showed the depression is 200 ft wide. Seismic data indicate it is probably a relict sinkhole that penetrated the shallow coastal aquifer and has been kept open (sediment-free) by artesian flow. Several vibracores were taken to determine the geotechnical stability of the overburden. Dr. Peter Swarzenski from USGS-St. Pete was aboard for geochemical sampling in the company of Jeff Davis of the St. John's River Water Management District (SJRWMD).

5/10-5/14: Seismic surveys were conducted along the coast of Daytona Beach, FL, to search for additional leaky collapse features. The 50-mile reconnaissance survey found at least 8 relict holes that may have penetrated the aquiclude, but which have been filled with sediments of an unknown porosity. Future studies could determine if fresh water is leaking from the aquifer through the overburdens. Based on the number of holes found during this first cursory investigation, future studies could also locate more. Jeff Davis of the SJRWMD was aboard conducting this survey.

5/21-5/28: Transited to Charleston, SC, to investigate the sedimentary environment surrounding the sunken Civil War submarine, H.L. Hunley. The first submarine ever lost in combat, the H.L. Hunley was found by Clive Cussler's National Underwater Marine Agency in May, 1995. The Naval Historical Center in Washington, D.C., is assessing the risks involved in raising her for subsequent preservation. Sidescan surveys, sub-bottom profiles, and vibracores around the site provided the shallow sedimentary data needed to develop a safe recovery/excavation plan. Dr. David L. Conlin, an underwater archeologist from the Naval Historical Center in Washington, D.C., was aboard overseeing these operations. Mark Hansen of USGS-St. Pete coordinated the interagency, cooperative effort.

6/8-6/21: Transited north to the Myrtle Beach, SC, area to conduct a seismic/sidescan/chirp-sonar survey of the nearshore sediments from Little River Inlet to south of Winyah Bay. Vibracores were taken to determine the composition and depositional sequences of Holocene/late Quaternary sediments. Vibracores were also taken wherever seismic data showed outcrops of the underlying unconformity. This is the first year of a multi-year program to define Holocene sediment thickness and distribution around the headlands. The data will be used by the USGS and Carolina Coastal University to determine historical barrier-island migration patterns, and by the State of South Carolina to assess future coastal stability. Dr. Robert Morton of USGS-St. Pete and Dr. Paul Gayes of Coastal Carolina University planned the surveys and designated the core sites.

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in this issue: Fieldwork cover story:
Grand Canyon

Gulf of Mexico Cruise

Georges Bank Benthic Habitat

Channel Islands

Lake Mead

Cruise News: R/V Gilbert

Great Bahama Bank

Outreach Nat'l Ocean Sciences Bowl

Meetings FL-AL-MS Geological Surveys

North Carolina Co-op

North East Mapping Organization

Atlantic Offshore Minerals Assessment

Staff & Center News WHFC Staff News


New Staff

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