Cultural Resource Investigation of Submerged Anomalies, Breton Sound Disposal Area, Plaquemines Parish, Louisiana. Phase 2.
GOODWIN (R CHRISTOPHER) AND ASSOCIATES INC NEW ORLEANS LA
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Five clusters of magnetic anomalies were recommended for ground truthing following Phase I remote sensing survey of the proposed Breton Sound Disposal Area, Plaquemines Parish, Louisiana. The present project concerned Phase II investigation of these clusters. Research methods involved magnetic survey of the five clusters at an interval of 15 m 50 ft, and examination of four of the clusters by divers. Search and excavation procedures were employed to locate the source of magnetic perturbation. Diving investigations and subsequent geophysical tests determined that the magnetic anomalies were caused by discreet areas of biological or chemical remnant magnetism associated with methane or natural gas seeps common throughout coastal Louisiana. The areas of anomalous magnetism are confined to a small zone around the gas seep and produce a magnetic signature that closely resembles that produced by a shipwreck. Recommendations were made to the New Orleans District to add sub-bottom profilers to the suite of equipment deployed on cultural resource surveys. Sub-bottom records will show gas vents as a blank area or blow out, which, when correlated with a magnetic anomaly, will suggest that the source is geologic rather than anthropogenic.
- Humanities and History
- Magnetic and Electric Field Detection and Detectors