Application of the flotation technique in arid areas

Abstract

The 1970 excavations at Tell el-Hesi, Israel, provided an opportunity (necessity) to adapt the flotation process to an arid area. While it is too early to present the findings of the research, a discussion of the process seems pertinent and, hopefully, will encourage more widespread use of the technique. Tell el-Hesi is located midway between Askelon and Beer Sheva in the northern portion of the Negev desert. Although there remains some discussion about its ancient name, the site is presumed to have been in the border area of ancient Philistia and Israel on a major trade route. Previous excavations of the site were by Sir Flinders Petrie (1) and Frederick J. Bliss (2) in the 1890's. The flotation technique used was that of Dr. Stuart Streuver (3). Basically, Streuver's method simply employs relative specific gravity to separate organic material from soil, stones, etc. It has two primary advantages. First, it allows for the recovery of very small seeds, etc., that would be missed by even the most careful examination of dry soil as it is removed from the site and, secondly, it permits examination of relatively large quantities of soil. This allows for the recovery of information heretofore thrown away with the spoil. The process requires relatively simple equipment that may be manufactured by local craftsmen at nominal cost and, ideally, a source of running water. Sources of running water have been rivers, streams, irrigation works, etc. To a very limited extent tap water has been used to process small samples. The location of Tell el-Hesi precluded access to a traditional type of water supply. Also, because of vehicular logistics of the expedition, it was not feasible to transport the samples to a source of running water. Therefore, it was decided to attempt the construction