Here is a replica of part of a wreck site. One of the main ways of plotting the position of objects is by using triangulation. Try it out for yourself.
Measure the distance from Point A to the red dot. Try to be as accurate as possible. Now do the same from at least two more points (B, C or D). Check your measurements against those taken by a professional underwater archaeologist. How well did you do? Are the measurements the same? They are? Then you've got what it takes to be an underwater archaeologist! If not, check the measurements again. Practice makes perfect!
The archaeologist would take these measurements and plot them on the map after scaling them down, using a pair of compasses. Say the measurement from Point A was 25 inches. If the map scale was 10:1, the compasses would be opened to 2.5 inches, the point put over Point A on the map and an arc would be drawn. The same would be done for all the other measurements. The object would be plotted where all the arcs crossed.
If you want, try out your new-found archaeological skill by measuring in the locations of other artifacts in the box.
Excavating is destructive, so archaeologist needs to be careful and record all the information they can as they dig.
They use several excavating tools, including water dredges, airlifts, water jets and even buckets and spades! The best tool is the diver's own hand. By fanning the water over the seabed, water current removes the sand without damaging anything. Without sucking it out of the way, the sand would just fall back down again, so archaeologists use tools to take away the sand for them.
The water dredge is perhaps the most common underwater digging tool. High pressure water is pumped down a hose and into the dredge, which creating a suction effect, just like a vacuum cleaner! It works well both in shallow and deep water, while another tool, the airlift works best if the water is at least 20 feet deep.
Instead of water, it pumps air into the bottom of a long pipe. This makes the airlift suck up water, just like the water dredge, but it is more powerful. If the water dredge acts like a household vacuum cleaner, then the airlift resembles an industrial sized cleaner.
- information supplied by the Miami Museum of Science.