Luminescence geochronology, especially infrared stimulated luminescence analyses on marsh mud, shows that a relatively deep lake reached its peak (∼1340 m above sea level) in the Bonneville basin 59,000 ± 5000 yr ago. The age is consistent with nonfinite 14C ages and with amino acid geochronology on ostracodes. The Cutler Dam Alloformation was deposited during this lake cycle, which, like the subsequent Bonneville lake cycle, appears to have reached its maximum highstand following the peak of a global glacial stage (marine oxygen-isotope stage 4) but at a time when other records from North America show evidence for cold climate and expanded glacier ice.
Bibliographical noteFunding Information:
Jack Oviatt and Rick Forester provided valuable input through all phases of this study. We thank J. Oviatt and an anonymous reviewer for their helpful comments on an earlier manuscript. The study was funded through a grant to DSK from the National Science Foundation (Grant no. EAR-9896251).
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- Pluvial Lake