The Provo shoreline of Lake Bonneville

Abstract

G.K. Gilbert studied the Bonneville basin 150 years ago and his findings have largely stood the test of time: The Provo shoreline, the most prominent geomorphic feature of Lake Bonneville, reflects threshold-stabilized overflow of the lake after the Bonneville flood and before a drier climate caused the lake to shrink. Subsequent refinements in chronology allow the Provo lake to be identified as about 18.2–14.8 cal ka BP, and stratigraphic studies show that the lake was gradually growing deeper during that time. Because the lake deepened through time as isostatic rebound occurred, individual landforms in general reflect processes operating for a small part of the ~ 3400 year of Provo time. Opportunities remain to improve our knowledge of the Provo lake; topics include (1) refinement of lake levels using delta and beach stratigraphy; (2) improved understanding of lake water chemistry and its role in determining deep-water sediment and cave deposits, which have disparate interpretations; (3) identifying processes at the threshold that caused the lake level to rise; and (4) identifying climate variability signals during Provo time.