CHC team tackles Alcatraz, Texas shipwreck preservation projects

Researchers from Texas A&M’s Center for Heritage Conservation visited Alcatraz Island in San Francisco Bay June 6-11, 2011 where they employed sophisticated surveying equipment to collect data that will be used to create detailed 2- and 3-D models of the island and its historic structures for documentation purposes.

Used as a military fortress during the Civil War, Alcatraz, from 1934–53, was home to a federal prison that counted among its notable inmates the notorious Chicago gangster Al Capone. Today, as part of the NPS’ Golden Gate National Recreation Area, the island is a popular tourist attraction, with visitors arriving by ferry over the bay’s cold waters from a San Francisco pier.

With the help of students from Chico State University and the National Park Service, Bob Warden and Julie Rogers, CHC director and associate director, used a total station, a tool that employs a laser distance meter to scan and record imaging data that, when entered into computer- aided design software like AutoCAD, yields accurate, highly detailed structural models.

Warden said the project was undertaken at the request of the NPS to demonstrate the types of historic imaging services performed by the CHC, how it could benefit their agency, and as a precursor to possible future collaborations.

Warden and Rogers also documented an outdoor concrete staircase that leads to a garden once tilled by prison inmates and now maintained by volunteers. The stairs are earmarked for restoration and preservation by Chico State students under the direction of Tanya Komas, who holds a Ph.D. in civil engineering from Texas A&M.

The island’s topography and weather conditions provided some challenges for the CHC research duo; the wind was blowing so strongly at times that students had to hold down the tripod supporting the 100-pound total station to perform some of the scans.

They also used the Total Station to scan a level area known as the “parade grounds,” part of an ambitious 19th century plan to level the entire island to increase its suitability as a military installation.

Several bird species discovered that that small portion of the island provided an ideal nesting spot, and since the CHC team’s trip coincided with the birds’ nesting season, measures had to be taken to scan the area without bothering the birds. To accomplish this, Warden said the Total Station was positioned on one of the island’s steep hillsides.

Preserving Texas history

Also this summer, Warden is collaborating with researchers at Texas A&M’s Center for Maritime Archaeology and Conservation to help preserve a 17th century shipwreck; part of the disastrous, final expedition by the French explorer René-Robert Cavelier, Sieur de La Salle.

In 1684, La Salle, who had already gained distinction as the first European to travel the length of the Mississippi River, claiming the land it drained for France, led another expedition to America to establish a colony at the mouth of the river. One of the expedition’s ships, La Belle, sank off the Texas coast in 1686 in what is now known as Matagorda Bay. La Salle was killed by mutineers March 1687 near present-day Navasota, Texas.

Texas A&M’s Center for Maritime Archaeology and Conservation is reconstructing La Belle’s hull and conserving its cargo and equipment, which were discovered in 1995.

Warden’s collaboration includes performing total station scans on the ship’s hull, which is being reassembled in a giant vat filled with water and a stabilizing compound that is gradually hardening the wet wood.

posted June 21, 2011