Chasing the Gradient: A New Diver-Held Tool for Locating Buried Shipwreck Remains in Magnetically Challenging Environments

Summary

This is an abstract from the session entitled "Plus Ultra: An examination of current research in Spanish Colonial/Iberian Underwater and Terrestrial Archaeology in the Western Hemisphere." , at the 2020 annual meeting of the Society for Historical Archaeology.

A new diver-held magnetometer was developed that directly senses the total magnetic gradient, and therefore effectively provides a direct signal if a magnetic (e.g., ferrous) object is in its vicinity, regardless of other ambient geomagnetic effects. The small (7cm diameter x75cm length), battery-powered device is neutrally buoyant, and provides an audio interface to the diver. The magnetometer was designed for and used in July 2019 during the Lost Ships of Cortés Project offshore Villa Rica, Mexico, an area with strong underlying volcanic geology and large quantities of magnetic sediment that mask buried archaeological materials. Magnetic anomalies were recorded during boat-towed magnetometer surveys, but divers could not identify their source using traditional underwater metal detectors. The new magnetometer decisively relocated an early 16th-century anchor at a range of several meters that was completely buried with its shallowest point at 50cm below the seafloor.

This Resource is Part of the Following Collections

• Society for Historical Archaeology 2020   •
• Plus Ultra: An examination of current research in Spanish Colonial/Iberian Underwater and Terrestrial Archaeology in the Western Hemisphere.

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Individual & Institutional Roles

Contact(s): Society for Historical Archaeology

Record Identifiers

PaperId(s): 943