GEOLOGIC MAP OF THE FISH LAKE 7.5 MINUTE QUADRANGLE, CENTRAL UTAH: INSIGHTS INTO THE VOLCANIC, TECTONIC, GEOMORPHIC, AND LACUSTRINE HISTORY OF THE FISH LAKE PLATEAU
Surficial deposits in the quad include alluvium, colluvium, and glacial deposits. The glacial deposits are composed of thick till units of two different ages with the younger unit having distinct morainal morphology. These deposits are from glaciers originating on the Fish Lake Plateau Hightop and from cirque glaciers on the E flank of the Hightop. Exposure ages of boulders on moraine crests indicate deposition of the younger moraines occurred at ~20 ± 2 ka with some recessional moraines yielding ages of ~16 ± 2 ka. Fish Lake is the largest alpine lake in Utah and is 7 km long by ~1.7 km wide. The NE end of the lake is partly occupied by glacial deposits from Pelican Canyon that have created a shallow lagoon filled with marsh. Fetch parallel to the long axis of the lake has created spits and bermed shorelines at the NE and SW lake margins. The maximum depth of the lake is 37 m and the average depth is 27 m. The gently sloped lake bottom is composed of organic-rich muds except over a prominent ridge where boulders dominate. This ridge is likely an older glacial moraine that is now submerged. Gravity data suggests sediment thickness in Fish Lake exceeds 100 m.