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Walsh discovered a quasi-permanent upwelling zone in East Bay, between South Pass and Southwest Pass of the Mississippi delta. He applied remote sensing to the study of physical characteristics of the sea surface around the delta. The purpose of cruise 68-A-14 of the R/V Alaminos was to verify Walsh's findings and to see if they were reflected in the bottom sediment.
In spite of a norther (cold front) coming over during the first days of the cruise and mixing the water body to a certain degree, the presence of cells with higher surface salinity and temperature than the surrounding water was substantiated. The bottom sediment distribution pattern shows an oval area underneath the salinity-temperature cells which is more silty than the surrounding sediments. Cores reveal that the cells were present during the accumulation of at least 7 m of sediment, indicating that the phenomenon is natural and not caused by warm brines released by the activities of the oil industry in this area.
Bathymetry analyses show a large variation in small topographic features and fewer gullies than indicated by Shepard a decade earlier. Comparing his and the present results, a trend of shallowing of East Bay seems to continue, but at a rather low rate.
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