Five deep sediment cores from the Bonneville Basin contain a rich tephra record encompassing the past 3.3 m.y. Twenty-two chemically distinct tephra layers were found, 15 of which correlate with previously described tephra from the western United States. Two of the remaining seven tephra layers are in the Glenns Ferry Formation of southwestern Idaho. The tephrostratigraphic framework of the Bonneville Basin provides a spatial and temporal framework for the sediments in this basin. Age-depth curves allow calculation of sediment accumulation rates (range: 8.9-27 cm/k.y.) and age estimates of the previously undescribed tephra layers. The Burmester core, which contains the longest and most complete record, has rates of sediment accumulation ranging from 1.7 to 20.9 cm/k.y.

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