Abstract

The Uinta Mountains in northeastern Utah are an east-west trending anticlinal structure that was formed during the Late Cretaceous and early Tertiary Periods. The core of the uplift consists primarily of Precambrian conglomerate, quartzose and feldspathic sandstone, and shale that are overlain by Paleozoic strata, including a succession of Mississippian limestones. In many areas, streams originating within the core of the mountains lose water into the carbonate rocks through karst features such as blind valleys. This water then discharges from large springs at lower elevations. Recharge areas for seven major springs in the eastern Uinta Mountains have been partially delineated by dye tracing. Along the south and southeast flank, groundwater generally moves down dip and along regional fractures and faults to discharge areas. In Ashley and Big Brush gorges, groundwater moves upward through the overlying fractured Weber Sandstone to discharge at the surface. In the northeastern Uinta Mountains, groundwater appears to move along geologic strike to discharge areas. On the basis of dye-tracer studies, maximum groundwater travel times from sink points to springs ranged from 1.4 to 14 days over corresponding linear distances of 1.7 to 16 mi (2.7 to 26 km).