Shoreline superelevation: Evidence of coastal processes of Great Salt Lake, Utah

The rise of Great Salt Lake to its historic highstand in 1986 and 1987 left shoreline expressions that can be identified by their debris, surveyed relative to known still-water lake elevation, and studied as evidence of coastal processes of shallow closed-basin lakes. Shoreline superelevation, the difference between still-water lake level and shoreline expressions, was quantified for the 64-km shoreline of Antelope Island, the largest island in Great Salt Lake. Elevations surveyed at 1228 locations around the island define a surface that is neither essentially horizontal nor at still-water lake elevation. Elevations range from 0.5 ft (0.2 m) below still-water lake elevation to 12.2 ft (3.7 m) above still-water lake elevation and average 2.9 ft (0.9 m) above still-water lake elevation. One-third of the elevations are more than 3.4 ft (1 m) above still-water lake elevation. Relative magnitude of shoreline superelevation is evidence of relative wave energy. Higher shoreline superelevation on Antelope Island is associated with longer fetch, shores that face to the west and northwest, steeper shorezone slope, and erosional coastal landforms.; Research findings on Antelope Island were tested around Great Salt Lake. Superelevation patterns around Gunnison Bay for pairs of shorelines with equal fetch show higher elevations along downwind shores that face into storm winds and lower elevations in the lee of land along the northeast shores of the bay. The contribution of wind strength to superelevation is explained by Great Salt Lake's fetch-limited size, with wave-generating areas sufficiently small that wave environments do not develop into fully arisen seas. For Great Salt Lake, contrasting patterns of eroding versus accreting coastal landforms and steep versus gentle shorezone slope are associated with shoreline superelevation and are evidence of wave energy and direction of storm winds.