GEOMORPHIC SIGNIFICANCE OF LAKESHORE LANDFORMS OF YELLOWSTONE LAKE, YELLOWSTONE NATIONAL PARK, USA

Yellowstone Lake (Yellowstone National Park, USA) is among the world’s largest high-altitude lakes (elevation 2,357 m above MSL). Well-developed lakeshore landforms include bay mouth/bay head bars and recurved spits. Development and evolution of sedimentary landforms is unusual in caldera lakes because lake margins are often very steep and descend to relatively great depths. At Yellowstone Lake, the best-developed lakeshore landforms are associated with the axis of maximum uplift of Yellowstone caldera, suggesting that tectonic processes are a first-order influence on geomorphic evolution of shoreline features. Along the northern lakeshore, relatively rapid uplift associated with caldera dynamics created a shallow (<10 m deep) platform on which nearshore landforms have developed. Areal dimensions of lakeshore landforms correlate with areal dimensions of the uplifted shallow terrace and the observed long-term uplift history of the caldera. Secondary influences on geomorphic evolution of lakeshore bars and spits are lake level oscillations (driven by seasonal and interannual climatic variability). Sediment supply to lakeshore settings is a tertiary influence on geomorphic evolution of lakeshore landforms, responding to uplift/subsidence and climatic variability. Investigating and understanding decadal records of lakeshore change will provide insights into the geomorphic significance of lakeshore landforms with respect to caldera dynamics, tectonically- and climatically-driven lake level oscillations, and variations in sediment supply/transport processes. These data may ultimately provide greater insight into the geologic history of the Yellowstone Lake system.