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Tracing the Source of the Elephant And Hippopotamus Ivory from ...

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sediment. As may be seen in Figure 55, <strong>the</strong> low strontium values follow <strong>the</strong> natural<br />

current counter-clockwise up <strong>the</strong> Levantine coast. The same researchers quote <strong>the</strong><br />

average value <strong>of</strong> Nile river sediments as 0.707043 and <strong>the</strong> average value <strong>of</strong> Saharan dust<br />

as 0.721788 (Waldeab et al. 2002: 142; citing Goldstein et al. 1984; Grousset et al. 1998,<br />

Krom et al. 1999). If <strong>the</strong>se values are used and <strong>the</strong> extrapolated inputs circa 1300 B.C.<br />

<strong>from</strong> Schilman et al. (2001) are considered, <strong>the</strong>n an estimate may be deduced for <strong>the</strong><br />

average strontium input to <strong>the</strong> eastern Mediterranean c. 1300 B.C.:<br />

87 Sr/ 86 Sr NS (percent input) + 87 Sr/ 86 Sr SD (percent input) =<br />

Average 87 Sr/ 86 Sr input to EM<br />

0.707043 (0.40) + 0.721788 (0.60) = 0.71589<br />

where NS = Nile Sediment, SD = Saharan dust, and EM = eastern Mediterranean.<br />

Figure 54: Ti/Al ratios plotted against calendar ages (ka), showing higher Saharan dust<br />

contribution at past times (65%) compared with <strong>the</strong> Nile particulate matter contribution<br />

(70%), which is higher towards <strong>the</strong> present<br />

(Schilman et al. 2001: 171).<br />

141

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