Page 276 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

Chapter 9: Excavation 255
Figure 9.11 Hand fanning into an airlift on Tektash site, Turkey. (Courtesy of Jeremy Green, Department of Maritime Archaeology, Western Australian Museum and the Institute of Nautical Archaeology, Bodrum, Turkey.)
objects (Figure 9.11). This system is quite impractical when removing large quantities of overburden. In this situation, the airlift is placed just above the overburden so that it is sucked up the tube, rather like a vacuum cleaner. Great care must be taken, but if the tube is kept above the spoil, it can be removed quickly and easily should artifacts appear. The airlift should only be operated this way when the visibility is good and with two skilled oper- ators working side by side, one operating the suction tube, the other watch- ing the spoil. Excavation is something of an art, and operators tend to get a feel for a particular site. It is often possible to detect differences in the composition of the material being excavated, which in turn indicate that artifacts may be anticipated or that the region is sterile. Common sense dic- tates the method; if you know from survey that there is 1 m of sterile sand over the archaeological layer there is no point in taking a long time to exca- vate it. A simple test is to check the spoil mound; if there are more than one or two artifacts there at the end of the day then one’s methods need to be revised.
In very shallow water there may be problems with discharging the spoil far enough off the site because the shallow depth restricts the distance that the airlift pipe can be set. In this case it may be possible to run additional lengths of pipe and float them on the surface a sufficient distance from the