Glacial Geology and Equilibrium Line Altitude Reconstructions for the Provo River Drainage, Uinta Mountains, Utah, U.S.A.

Abstract

ABSTRACT The Provo River drainage in the western end of the Uinta Mountains was glaciated repeatedly during the Pleistocene, and glacial deposits from the Smiths Fork and Blacks Fork glaciations (Pinedale and Bull Lake equivalents, respectively) are well preserved throughout the area. Reconstruction of the Smiths Fork ice extent based on air photo analysis and field mapping reveals that the broad upland surfaces in the Provo River drainage were covered by an ice field from which distributary glaciers emanated. This ice field also covered parts of the Weber and Bear River drainages to the north and the North Fork Duchesne drainage to the east. Equilibrium line altitudes for glaciers in the Provo River drainage were ∼2900 m a.s.l., consistent with previous studies which recognized a dramatic decrease in equilibrium line altitudes toward the western end of the range. End moraine sequences and hypsometric differences between glaciers in the Provo River drainage suggest that ice retreat rates likely differed considerably among the glaciers, reflecting variable dynamic responses to a similar climate forcing during deglaciation.