Transgressive stratigraphic record and possible oscillations of late Pleistocene Lake Bonneville, Northern Hogup Mountains, Utah, U.S.A.

• There are 7 major oscillations during the transgressive phase of Lake Bonneville.
• Two of these oscillations are newly proposed from this study.
• The stratigraphic patterns of outcrops provide the best evidence for the oscillations.
• The oscillations likely correlate to rapid regional climatic drivers during the LGM.
• No clear correlation between timing of oscillations and hemispheric climatic events.

Distinct, mappable facies changes make the stratigraphic record of the shorezone of late Pleistocene Lake Bonneville the most robust indicator for past lake level oscillations. Unfortunately, clear stratigraphic evidence of transgressive and regressive deposits has been generally lacking. New stratigraphic and chronological data within the lacustrine shorezone sediments of the Hogup Mountains of northwestern Utah provide some of the best evidence yet for oscillations within the overall transgressive phase of the lake. This study documents two previously unknown oscillations, hereby named the Lower Hogup (~ 22 cal ka) and Upper Hogup (~ 20.6 cal ka) oscillations and provides further evidence for the previously proposed U2 oscillation (~ 21.3 cal ka). The study suggests that the water level of the lake changed dramatically (up to 25% of the lake’s total volume) during the transgressive phase (~ 30–15 cal ka). With the additional oscillations documented in this study, there are seven proposed oscillatory events during the transgressive phase of the lake. These events likely correlate to rapid but short term regional climatic fluctuations during the broader climatic trends of the Last Glacial Maximum. However, it is still unknown what specific climatic drivers are causing these oscillations and if these events can be correlated to other global climatic events.