An Archaeological Remote-Sensing Survey and Target Assessment for a Borrow Area Offshore of Tybee Island, Chatham County, Georgia

Olsen Associates. Inc. is the project engineer that represents the City of Tybee Island in its

efforts to develop an offshore borrow site for beach nourishment material. In order to

determine the proposed project's effects on potentially significant submerged cultural

resources, Olsen Associates contracted with Tidewater Atlantic Research, Inc. of

Washington, North Carolina to conduct a magnetometer and side-scan sonar survey of the

proposed borrow site. Field research for the project was conducted between 12 and 14

January 2008. Analysis of the remote sensing data generated during the survey identified a

total of 54 magnetic anomalies. None of the magnetic anomalies had an associated acoustic

signature. Analysis of the data indicated that twelve clusters composed of 21 of anomalies

have signature characteristics consistent with shipwreck material and/or other potentially

significant submerged cultural resource. All twelve target clusters are formed by spatially

associated anomalies. Because the survey area had a high potential for historically significant

shipwrecks, those twelve target sites are recommended for avoidance or additional

investigation. The remaining 33 targets are small single source signatures that appear to have

been generated by modern debris such as fish an l crab traps, pipes, small diameter rods, cable,

wire, rope, chain, small boat anchors. No additional investigation of those site is

recommended in conjunction with the proposed dredging. In order to identify and assess

material generating two or the potentially significant targets diver reconnaissance of the

anomalies was subsequently authorized by Olsen Associates a11d was carried out by

Tidewater Atlantic Research on 14 February 2008. Material generating the primary anomaly

at each target site proved to b modem d bris. Systematic probing carried out to depths

of 10 feet below bottom surface at both target sites to ensure that modern material was no

masking earlier and potentially significant submerged cultural resources No additional

investigation of these sites is recommended in conjunction with the proposed dredging plan

for Area 2. Areas l and 3 contain no anomalies and no additional investigation is

recommended. Should future dredging be required in the remaining northern portion of the

Survey area, anomaly avoidance or additional investigation is recommended to assess the

historical significance and impacts of dredging on material generating those targets.