Nautical archaeology

Nautical archaeology (pronounced NAW-tih-kul ar-kee-OL-low-jee) is the science of finding, collecting, preserving, and studying human objects that have become lost or buried under water. It is a fairly modern field of study since it depends primarily on having the technology both to locate submerged objects and to be able to remain underwater for some time to do real work. Whether it is conducted in freshwater or in the sea, and whether it finds sunken ships, submerged cities, or things deliberately thrown into the ocean, nautical archaeology is but another way of exploring and learning more about the human past.

Archaeology done underwater

Although some use the words nautical archaeology to mean a specialized branch of underwater archaeology, which is concerned only with ships and the history of seafaring, most consider the term to mean the same as the words underwater archaeology, undersea archaeology, marine archaeology, or maritime archaeology. All of these interchangeable terms mean simply that it is the study of archaeology being done underwater. Archaeology is the scientific study of the artifacts or the physical remains of past human cultures. By studying objects that ancient people have made, we can learn more about how they lived and even what they were like. In fact, studying ancient artifacts is the only way to learn anything about human societies that existed long before the invention of writing. For those later societies that are studied, being able to examine the actual objects made and used by those people not only adds to the written records they left behind, but allows us to get much closer to the reality of what life was like when they lived. Also, if we pay close attention to how the objects were made and used and what were their purposes, we begin to get a much more realistic picture of what these people were really like.

Underwater repositories of human history

Ever since the beginning of civilization and mankind's ability to move over water, the bottoms of nearly all oceans, lakes, and rivers became the final resting place for whatever those vessels were carrying. Once real trade began, it is safe to say that nearly every object made by humans was probably transported over water at some point in time, and just as frequent were mishaps and accidents of all sorts that resulted in those objects sinking to the bottom. Vessels of all types—from canoes, rafts, and barges to seafaring ships—became victims of every imaginable disaster. Vessels were sunk by severe weather and fierce storms, by construction defects and collisions, by robbery and warfare, by hidden sandbars and jagged reefs, and probably just as often by simple human error and misjudgment. Some cultures may have thrown things into the sea, perhaps to appease an angry god, while others conducted burials at sea. Finally, entire coastal cities are known to have been totally and permanently submerged as the result of an earthquake. All of these and more resulted in the creation of what might be called underwater repositories of human history.

Destroyed or preserved

Not all of these objects survived either the trip down to, or their stay on, the bottom. Their fate depended on where they landed. If an object sank near the seashore, chances are that it would have been broken by wave action. Even if it sank far below the action of waves, it still might not have survived, since it could have landed on submerged rocks and been broken by ocean currents. Sometimes underwater creatures, like snails and worms, burrowed inside and ate them, while others like coral or barnacles may have cemented themselves on the surface of an object and rotted or rusted away its inside.

However, besides hiding or destroying objects, the sea can also preserve them. Objects that sank into deep layers of mud were hidden from sight but were usually well-preserved. Often the saltiness of the water discouraged the growth of bacteria that can rot organic materials like wood. Other times, metals were buried in mud that allowed little or no air to get in, thus preventing them from corroding. It is not unusual, therefore, to discover ancient ships that have been deeply buried whose parts—from their wood boards to their ropes, masts, and nails—and cargos of pottery or weapons or even leather and cloth have been perfectly preserved.

Underwater technology

People have been finding submerged objects of all sorts for as long as they have been able to get and stay below the surface. Early sponge divers were probably among the first, since they were expert at holding their breath and working underwater. Although primitive diving suits were used as early the sixteenth century, it was not until the nineteenth century that helmet diving gear was invented that allowed a person to "walk" on the bottom and explore it. Connected to the surface by an air hose and wearing what must have felt like a heavy suit of armor, the diver was clumsy and very slow and could never get very much done during his short trips to the bottom.

Nautical fossils are examined in much the same way as fossils found on dry land. (Reproduced by permission of

The Corbis Corporation [Bellevue]

.)

Nautical archaeology did not become a feasible pursuit until the invention in 1943 of an underwater breathing device by French naval officer and ocean explorer Jacques-Yves Cousteau (1910–1997) and Emile Gagnan, also of France. Called scuba gear for self-contained underwater breathing apparatus (and trademarked under the name Aqua-Lung), it revolutionized diving and allowed a person to swim freely down to about 180 feet (55 meters) wearing only a container of highly compressed air on his back. It was later improved by using a mixture of oxygen and helium rather than normal air (which is oxygen and nitrogen), and this allowed a diver to descend as deep as 1,640 feet (500 meters). Until this invention, actual underwater exploring had been done mostly by professional divers who were directed by archaeologists. With this new scuba gear, however, archaeologists could explore themselves. From this, modern nautical archaeology was born.

Improving technology

The first underwater site to be excavated (exposed by digging) by diving archaeologists was a Bronze Age (c. 1200 B.C. ) ship wrecked off the coast of Turkey. It was explored by Americans Peter Throckmorton and George Bass, who became pioneers in the field. They and all others to follow used nearly the same techniques that archaeologists on land always

This fossilized spadefish is over 50 million years old. (Reproduced by permission of

The Corbis Corporation [Bellevue]

.)

follow, although working underwater made their job one of the most difficult and demanding of all scientific activities.

Today, nautical archaeologists employ a variety of technologies and techniques that make their job easier. They sometimes use aerial photographs to get detailed pictures of shallow, clear water. They often use metal detectors or a magnetometer (pronounced mag-neh-TAH-meh-ter) to find metal objects. Sonar devices send waves of sound through the water that bounce off solid objects and return as echoes, which are recorded by electronic equipment. Underwater cameras are regularly used, as are remotely operated vehicles that can penetrate to extreme depths where severe cold, high pressure, and total darkness would prevent humans from going. Finally, before excavating, nautical archaeologists carefully study and map a site (the location of a deposit or a wreck). This is probably the most time-consuming part of the job, as each artifact is drawn on a map to note its exact location. Only after the entire site is mapped will removal begin. This is done using several different methods. Balloons or air bags are often used to raise large or heavy objects. Vacuum tubes called airlifts are used to suck up smaller objects or pieces. Certain objects brought to the surface must be properly cared for or they can fall apart in a matter of days. Nautical archaeologists must therefore have ready a thorough plan to preserve these fragile objects once they are raised.

Nautical archaeology is still a young science, but it has achieved some spectacular results. Entire ships, like the Swedish warship Vasa , which sank in 1628, and the even older English ship Mary Rose, have been raised. The Vasa took five years to raise; the Mary Rose took nearly twice that long. The wreck of the Titanic, which sunk in 1912 after hitting an iceberg, has been thoroughly explored ever since it was first located by a remote-control submarine in 1985. As technology improves, so does the ability of nautical archaeologists to explore the hidden museum under the sea that holds more clues about our human past.

[ See also Archaeology ]