The clinchers, says Stanley, are the concentration and composition of the lead found in one of the pre-Greek layers. The lead concentration was markedly higher than that found in sediments known to precede human contact—suggesting the presence of people—but milder than that from post-Alexander times. And while post-Alexander lead came from metallurgy, the lead in the pre-Greek layers was derived from clay used in pottery and mortar.
Both findings confirm not only human activity but also human activity in a distinctly different time and settlement than Alexandria, says Richard Carlson, a geochemist with the Carnegie Institution of Washington, D.C. who conducted the lead analysis and interpretation.
"The enhanced lead signal in the pre-Alexander sediment indicates that they were importing a substantial amount of clay and building a settlement," Carlson says. The lead composition changed in the post-Alexandria period, he says, with the increased use of metallurgy, paints and pigments.
Stanley and his colleagues are hesitant to make larger speculations about Rhakotis at this point, shying away from describing it as industrial but suggesting it may not be as modest as originally conceived.
"We've got evidence of humans—a good, hard base that there is something there," Stanley says. "Now that we've established this baseline, intense work could do an awful lot in this next decade to highlight where this town was, who was in it, and what they were doing."