USA: Florida II Survey Vessel Suitable for Archaeological Research
The Florida II is a survey vessel, but it has the capability to provide much more information than just water depth. The design specifications and specialized equipment it carries make it possible to do many different types of surveys, and suitable for underwater archaeological research.
“As part of National Environmental Policy Act (NEPA) compliance, we have to do cultural resource surveys on all projects we initiate, whether they are terrestrial or underwater, at least a year in advance of work being done,” said Natalie Garrett, archaeologist. “That includes upland dredge disposal sites and inlets like Jacksonville Harbor. We need to make sure that there are no historic sites, including shipwrecks, such as those from the Civil War and World War II.”
“We have to identify any sites within our project areas and coordinate with the State Historic Preservation Officer (SHPO) and Tribal Historic Preservation Officer (THPO) and take any actions required to make sure the sites aren’t adversely affected,” said Wendy Weaver, an archeologist with special training in underwater archaeology, who has been evaluating terrestrial and submerged cultural resources with the U.S. Army Corps of Engineers for five years.
During a cultural resources survey, archaeologists look for historic properties, including structures, shipwrecks and potential prehistoric or other archaeological sites.
Shipwrecks are protected by the state of Florida, and in federal waters, they are protected under the National Historic Preservation Act (NHPA) and the Abandoned Shipwrecks Act. Sometimes there will be a buffer zone around a site, and prohibitions against any bottom-disturbing activities, such as dredging, dumping or anchoring.
“I was really impressed with the capabilities of the Florida II. We are capable of doing many archaeological surveys in house, rather than having to contract [the work] out,” said Weaver.
The Florida II is fully equipped with specialized software, hardware and equipment that is deployed and towed off the stern of the vessel. One specialized piece of equipment that can be towed is a magnetometer, which is similar to a metal detector. It picks up on materials that have some component of iron, but does not detect gold, silver, aluminum or brass. Things like fiberglass hulls would not be picked up, but rigging and engine parts would. Metal ship hulls, cannons, anchors and anchor chains and even old wooden shipwrecks with nails could be detected, as well as things like unexploded ordnance. Magnetometers are also helpful for finding shipwrecks that have been covered by sand during hurricanes.
Another feature is the side scan sonar, which takes a picture of the surface using sound waves. It can find boats, debris and objects like crab traps sitting on the surface.
The sub-bottom profiler penetrates below the surface. It shows reef areas and other formations that might support marine life, as well as old shorelines, where it is common to have archeological sites. It can show things like old riverbeds and shell middens, piles of shell that may indicate that there was an archaeological site there before the sea level rose and covered it.
Archaeologists know that archaeological sites on land often project out onto the continental shelf, since some of the areas that are currently underwater once were previously on dry land. For example, when the paleochannels (former river channels that don’t exist anymore because they are now totally underwater) of the Econfina and Aucilla Rivers were followed three miles out into the Gulf of Mexico, archaeologists found a mastodon kill site in about 15 feet of water. Arrowheads, mastodon teeth and bones were evidence that the site was where a huge mastodon was killed and butchered.
“That’s why it’s important to look for archaeological sites underwater,” said Weaver. “There’s always the potential for them to occur. We have found some promising sub-bottom data on the Atlantic Coast, but haven’t identified any archaeological sites as of yet.”
“We have done some surveys in smaller vessels in shallower water, but offshore, the Florida II provides a bigger, more stable platform that allows work to continue even in rougher weather,” said Weaver. “In addition, the survey grid is programmed in, so the transects that the vessel follows are very uniform.”
USACE, July 23, 2014