The Quaternary stratigraphy of the Henrys Fork and Western Browns Park, northeastern Uinta Mountains, Utah and Wyoming

Surficial deposits were mapped at l:24,000 scale to develop a Quaternary stratigraphic framework for the northeastern Uinta Mountains. The Henrys Fork stratigraphy includes ten mainstem gravels, six piedmont gravels, and landslide deposits. Henrys Fork terraces converge downstream and are strath terraces underlain by gravel. The Browns Park stratigraphy includes eight mainstem gravels, five piedmont gravels, and various landslide, colluvial, and eolian deposits. Lava Creek B ash was identified in the Browns Park Stratigraphy. Incision rates were estimated at 80--110 m/m.y. on the Henrys Fork and ∼85 m/m.y. on the Green River. These rates are significantly lower than the rates reported for the south flank of the Uintas and other central Rocky Mountain ranges. A series of three distinct deposits in western Browns Park are interpreted as evidence for the landslide impoundment and subsequent outburst flooding of the Green River. Peak discharge estimates the resulting outburst flood was ∼22,000 m3/s.