Monday, May 21, 2012

In the Gulf’s depths, a rare time capsule

NOAA's Seirios Camera Platform, operating above the Little Hercules ROV, images the ROV and an anchor inside the hull of a copper-sheathed shipwreck in the Gulf of Mexico.
The wood has nearly all disintegrated after more than a century on the seafloor.

From NYT

Four thousand feet beneath the surface of the Gulf of Mexico and 200 miles south of Louisiana’s marshy coastline, a machine called Little Hercules levitates in the darkness above the bow of a decaying wooden ship.
Much of the wreckage has disintegrated over the many decades that the ship has soaked on the ocean floor, but Little Hercules’ lights illuminate a skeletal scrub forest of sea creatures thriving on what remains.
Little Hercules, a remotely operated vehicle, was put to work a few months ago by the National Oceanic and Atmospheric Administration to search the nooks and crannies of the Gulf of Mexico’s depths.

From March to April 2012, a team of scientists and technicians both at-sea and on shore will conduct exploratory investigations on the diversity and distribution of deep-sea habitats and marine life in the northern Gulf of Mexico.
The video footage was captured by the Little Hercules ROV and Seirios Camera Sled platform during the April 3rd ROV dive.

Using bright lights and an assortment of high-definition video and still cameras, the R.O.V. has been exploring deep-sea habitats and possible shipwrecks and reporting back to members of a NOAA expedition onboard the ship, the Okeanos Explorer.

While most of the ship's wood has long since disintegrated, copper that sheathed the hull beneath the waterline as a protection against marine-boring organisms remains, leaving a copper shell retaining the form of the ship.
The copper has turned green due to oxidation and chemical processes over more than a century on the seafloor.
Oxidized copper sheathing and possible draft marks are visible on the bow of the ship.

On the night of April 26, Little Hercules’ high-definition cameras revealed the exciting wreckage of the copper-hulled ship, which archaeologists think probably dates from the early 1800s.

“This wreck is from a period very critical to the history of the Gulf of Mexico,” said Jack Irion, a maritime archeologist with the federal Bureau of Ocean Energy Management, a partner in the expedition. He said that because the wreck laid so deep underwater, “it’s virtually untouched by any sort of storm or human activity.”
Dr. Irion has dated the wreckage primarily on the basis of a ceramic plate he saw in the photographs and videos of the wreckage.
He said that this sort of “pearlware,” with a green strip around the scalloped outer edge of the plate, was highly popular from around 1800 to 1830.

An anemone lives on top of a musket that lies across a whole group of muskets at the site of the shipwreck.

Early in the 19th century, many empires – Spanish, French, British, the United States – were vying for power in the Americas, and the Gulf of Mexico brimmed with vessels out to pirate, battle and trade, Dr. Irion said.
Riches taken from Central and South America were often shipped from the Mexican port of Veracruz, where the ships caught a loop current sweeping along the rim of the gulf toward the Florida Keys, he said.
“Little is known about the gulf and the cultural resources that exist there,” said Frank Cantelas, a maritime archaeologist with NOAA who will continue analyzing imagery from the wreckage.
He said that researchers can learn a lot about the people who lived in a specific time and place through the remains of a sunken ship.
“Wrecks are like a time capsule,” Mr. Cantelas said. So far, he has  seen a variety of hourglasses, navigational tools, cannons, muskets and glass bottles, some holding their original contents, in ship wreckage.

Researchers are not yet sure of this ship’s national origin or mission.
At the suggestion of the ocean energy bureau, Little Hercules and the researchers aboard the Okeanos Explorer investigated five different shipwrecks during the expedition, which ended on April 29.
Oil companies and other businesses that wish to develop parts of the ocean floor must first get permission from the bureau.
Usually those companies will use sonar equipment to independently explore the places they would like to develop.

 A map produced by NOAA Ship Okeanos Explorer's sonar shows the West Florida Escarpment, a steep undersea cliff.
The base of the escarpment (2,600 meters deep) is shown in blue with the upper rim more than 600 meters above.
ROV dives explored the physical structure of the seafloor and biodiversity on soft and hard bottom areas.

They create basic bathymetric maps of the sea floor and then submit their maps to the bureau.
The agency used the maps to pick out areas on the bottom of the Gulf of Mexico that seemed out of the ordinary – perhaps a shipwreck, but maybe just a pile of sediment – so that NOAA could look more closely.
The oil giant Shell was the first to notice the strange bathymetric blip that proved to be the exceptional wreckage of the 19th-century ship.

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