The sea, any marine archeologist (or buccaneer) will tell you, guards its secrets jealously. First, one must locate a shipwreck and its associated artifacts. Once found, wrecks must be mapped and explored, and artifacts must be retrieved with extreme care. Some lost articles, when exposed to the air after resting safely in the abyss for hundreds or thousands of years, can turn to mush before you can growl "Look lively there, ye lubbers!"
Finding soggy shipwrecks has gotten easier over the past fifty years. With the advent and refinement of scuba technology, they've come within easy reach of marine archeologists -- and of sport and commercial divers who enjoy a good wreck as much as the next swab. It has also helped modern-day scoundrels who, like the pirates of olde, think nothing of pocketing anything that's not nailed down, and even artifacts that are.
How has technology expanded the archeologist's reach to ever deeper waters?
The mainsail of modern underwater archeology technology is the magnetometer, a device that, when towed behind a boat, senses variations in the Earth's magnetic field caused by junk metal -- say ship hulls and cannons. It was this instrument that gave the wreck hunters of Intersal, Inc., the first interesting indications in 20 feet of murky water off North Carolina's Beaufort Inlet. These readings were caused by a submerged wreck that may have belonged to that ogre of a pirate, Blackbeard. We covered that back here, in case you missed it.
Richard Lawrence, the underwater archeologist for the state of North Carolina and the scientist overseeing work on the Queen Anne's Revenge, says using a magnetometer to scour the bottom is "like mowing a big lawn, going back and forth and back and forth, covering 60-foot swaths" of ocean.
For locating wrecks that might add to our store of piratical knowledge, the archeological arsenal now includes nifty toys like the "laser line-scan." This device, also used to search for the wreckage of TWA Flight 800, has a laser-packed head that spins at nearly 3000 RPM. Laser pulses, fired downward, bounce off the sea floor back to the ship, where they are recorded and processed by computer.
"It's a neat instrument that can almost give you photographic coverage of the bottom," says Lawrence.
Lots of underwater archeologists would love to be the first scientist on the block to acquire such a new-fangled toy, but it comes with a hefty price tag, according to David J. Cooper, underwater archeologist for the State Historical Society of Wisconsin.
"One thing about underwater archeology," notes Cooper, "is that the cutting-edge of technology is so expensive most scientists are using tried and true methods" like a trusty old magnetometer towed behind a Boston Whaler.
A menu of new technology
Nevertheless, new technology, much of it developed for the military, is already playing a significant role in reconnoitering Davy Jones' Locker, according to Cooper. The new ways of looking down include:
- High-Resolution Side-Scan Sonar -- A device that shoots out high-frequency sound waves and records the echoes. Processed by computer, the signals can provide near-photographic resolution of the sea floor.
All of these new technologies have the potential to increase the scope and reach of underwater archeology. But if you really want to get your hands on some major treasure-hunting technology, you've gotta go nuclear.
- Sub-Bottom Profiler -- This instruments sends out low-frequency sound pulses that can penetrate the sea bed. It's a very handy thing to have since many relics are covered by sediment.
- Artificial Intelligence -- To sort through acoustic signals and separate the mines from the oil drums floating in the ocean, the military has invested heavily in the development of computer codes to distinguish the harmless from the lethal. Such programs can massage data lickety split, eliminating the tedious and time-consuming task of sorting through mountains of data by eye.
- Global Positioning System -- GPS is a satellite-based navigational aid that provides unprecedented spatial accuracy for anyone on the planet -- with the right equipment. A GPS receiver can tell you precisely where you are on (or near) the planet within a few meters. This is useful for returning to a treasure ship you might discover in a featureless patch of ocean.