Florida Keys Maritime Archaeological Field School

In The Florida Keys National Marine Sanctuary
Photographs From The 2005 Field School On The Button Wreck
19th July to 9th August

Once the site had been located, the next task was to conduct a geophysical survey.

During the field school, an AX2000 Proton Magnetometer made by Aquascan International Ltd, was used to survey the site.  ADMAT owns one and an additional back up proton magnetometer was kindly loaned to the project by Aquascan International Ltd. Dr Spooner has been using this proton magnetometer for the last 10 years on projects world wide. This is one of the fundamental tools, and is designed to detect ferrous objects, whether they be on the surface or buried under the seabed. Items such as cannons, anchors and rigging can be detected and pinpointed.

The survey required the survey boat to run parallel lanes about 10 meters apart over the entire site and the surrounding area. The magnetometer fish is carefully lowered into the sea and towed on its cable. The AX2000 control panel is watched and any changes in the earths magnetic localised field are recorded. This can be as a result of cannons or other large iron masses. The survey boat has to steer a careful course and at speeds not more than 2 knots, which is very hard to do.

A rectangular area of 500 metres by 600 meters was surveyed, as well as an area to the north of the site. In this survey area there were only two magnetometer hits. The first one was the gudgeons which gave an excellent sign wave on the AX2000 control digital screen. The second was unknown as it is buried under the sand.

The grid was then deployed and constructed underwater by the entire team.