BONNEVILLE BASIN ENIGMA, TECTONIC DROP OF LAKEBED CAN RESULT IN RAISED SHORELINE EVIDENCE

Shoreline evidence of the Bonneville basin can and has contributed to an understanding of (a) the evolution of the Great Basin and Basin and Range Physiographic Province, and (b) seismic hazards of the Wasatch Front. How do shorelines record downward displacements within Lake Bonneville? Specifically, how might shorelines created at the Provo and Bonneville levels, while lake level was threshold controlled, have responded to downward basin displacements? Shorelines in the lake’s main body could appear higher as well as younger than their pre-displacement expressions. Shoreline evidence in the main body could contrast with that of Cache Valley. This scenario indicates how tectonic displacements further complicate correlation of today’s evidence of Lake Bonneville’s shorelines. Conversely, these complexities of shoreline evidence may provide insights to Bonneville basin tectonics. If confirmed, this scenario provides evidence of relative downward displacement along Bonneville basin faults.