THE OSCILLATORY RECORD OF LATE PLEISTOCENE TRANSGRESSIVE PALEOSHORELINES OF LAKE BONNEVILLE

New stratigraphic and chronological data within the lacustrine sediments of the Hogup Mountains of northwestern Utah provide evidence for two previously unpublished oscillations and further evidence for another previously proposed oscillation in the transgressive record of late Pleistocene Lake Bonneville. Since the lake’s level is closely tied to climatic responses, resolving stratigraphic and chronologic history has the potential to improve the resolution of regional and global paleoclimate models. The sedimentological deposits at this site are related to the transgressive paleoshorelines between the altitudinal limits of the Bonneville and Provo levels (Intermediate paleoshorelines). Including the two newly proposed oscillatory events from this paper, there are seven proposed oscillatory events during the transgressive phase (25 – 14.5 ¹⁴C kyr B.P.) of Lake Bonneville: two Stansbury oscillations (~21.5 and 20.5 ¹⁴C kyr B.P.), the U1 oscillation (~18.6 ¹⁴C kyr B.P.), the newly proposed Lower Hogup Oscillation (~18.2 ¹⁴C kyr B.P.), the U2 oscillation (~17.5 ¹⁴C kyr B.P.), the newly proposed Upper Hogup Oscillation (17.2 ¹⁴C kyr B.P.), and the U3 oscillation (~16.4 ¹⁴C kyr B.P.). It is proposed that these Intermediate oscillations record sub-millennial oscillations in the lake level that likely correlate to short-term climate shifts during the Last Glacial Maximum.