Abstract

Lakes expanded and contracted in the Bonneville basin many times during the Quaternary as shown by deep sediment cores and surface stratigraphic sections. The timing of certain middle and early Quaternary lakes is well documented based on dated volcanic ashes, amino stratigraphy, and other techniques. Although freshwater lakes probably existed in the Sevier Desert subbasin of the Bonneville basin when the Bishop ash was deposited (740,000 yr B. P.), the lake in the Great Salt Lake basin was probably contracted at this time. Bishop ash was deposited during marine oxygen-isotope stage 19, an interglacial episode. An expanded deep lake immediately preceeded the deposition of the Lava Creek B ash (620,000 yr B.P.), and was broadly correlative with marine oxygen-isotope stage 16. The Pokes Point lake cycle may be correlative with oxygen-isotope stage 8, and the Little Valley lake cycle with stage 6. Other early and middle Quaternary expanded-lake episodes have been inferred from studies of sediment cores, but their relationships to the global record of glacial-ice volume in deep-sea cores is not yet known.