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The Paleoecology And Geomorphology Of Holocene Deposits Of The Southern Malad River, Box Elder County, Utah, Ann Schaffer Elder

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Widespread Lake Bonneville sediments have been modified by river aggradation and degradation associated with Holocene fluctuations in the Great Salt Lake. Exposures of exceptionally abundant and well-preserved molluscan deposits in the Bear River Valley, Utah, allow detailed paleoenvironmental reconstruction of Holocene environments. The exposed basal unit consists of largely unfossiliferous deltaic silts and clays deposited during Lake Bonneville time (roughly 11,000 - 13,000 yr B. P.). An unconformity representing at least 2000 yr separates the deltaic material from overlying highly fossiliferous stream sands. Eight species of molluscs, comprising a single community, occupied this low energy stream environment at 7690 ± …