Underwater archaeological excavation is very similar to traditional land archaeology.We use similar tools but usually the plastic version of the tool so that it does not fall apart in the salt water.Organic material such as bone, plant fibers, seeds, branches, and an incredibly array of perishable technology is often better preserved underwater than it is on land.Well buried and undisturbed underwater sites provide very stable conditions which aid in preservation much like being in a very dry cave in some portions of the American Southwest.The archaeological goal of excavating materials in a controlled fashion where the original location of each object or artifact can be recorded and analyzed later is the same wherever you dig.The methods employed as we work underwater are slightly different because of the environment and the need for some different tools.Aerial Reconnaissance - The technique of searching for sites and features, both cultural and natural, from the air, often using aerial photography or the human eye.
More flakes were knocked off from both sides of a stone and there is evidence that the maker had a preconceived notion of the tool's final form.
However, rather than shovel dirt into a bucket or wheelbarrow and bringing it to a fine screen to shake it, or wash it with water to remove the dirt, we use a 100ft hose connected to a large dredge engine with a pump that moves 600 gallons of water a minute to suck the seafloor sediments like a giant vacuum cleaner.
The dredge tube brings the sediments from the bottom and deposits them on our 8 by 12 foot floating screen deck that has mesh as fine as 1/16th of an inch to catch even the smallest of artifacts or bone fragments.
Typically, organic materials are brought to the surface and stabilized as soon as possible.
This is doubly important if we hope to directly date the object with a radiocarbon assay.