Ground-penetrating radar and terrestrial laser scanning reconstruction of the prison and Civil War era historic fortifications on Alcatraz Island

Summary

Between 2012 and 2013 we conducted a cultural resources assessment and historic preservation project with the National Park Service on Alcatraz Island using terrestrial laser scanning and ground-penetrating radar. Alcatraz is most (in)famous for its brief period as a Federal Penitentiary (1934-1963); however, for the vast majority of its history it was a military fortification – Fortress Alcatraz - under the U.S. Army. As the need for harbor defense diminished, the island was converted into a military prison during the 1860’s. The conversion of the island to a prison greatly reduced the surface record of this historic period. An analysis of georectified historic maps showed that historic masonry and earthen work fortification structures once stood in the Parade Ground and Recreation Area of the island. Ground-penetrating radar with 200 and 500 MHz antennas was used to detect the presence, integrity, and extent of these significant historic remains below the islands current prison facade. Laser scanning was undertaken to obtain a current 3D reproduction of the island. The integration of GPR and laser scanning data was used to create a 3D reconstruction, which allowed for a greater understanding of the process of change over time on the island.

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This Resource is Part of the Following Collections

• Society for American Archaeology 80th Annual Meeting, San Francisco, CA (2015)

Keywords

Spatial Coverage