Use of Chemical Composition of Freshwater Clamshells as Indicators of Paleohydrologic Conditions

Use of Chemical Composition of Freshwater Clamshells as Indicators of Paleohydrologic Conditions

1969

The feasibility of using the Ca, Mg, and Sr content of freshwater clamshells as indicators of paleohydrologic conditions has been investigated. The Sr/Ca ratio varies with the discharge of Mill Creek, Iowa. The Sr/Ca ratios of clamshells excavated from American Indian midden sites near the Big Sioux River in Plymouth County, Iowa (Kimball Site 13 PM 4), and the Phipps site (13 CK 21) located near Mill Creek in Cherokee County, Iowa, show significant changes that can be related to changes in climate in the period 900 to 1400 A. D. Based on the results of this investigation, the alkaline earth composition of freshwater clams probably can be used as an indicator of paleohydrologic conditions.

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