T50 Great Geological Outcrops and Locales

Sunday, 10 October 2021
1:30 PM - 5:30 PM
Portland Ballroom 253 (Hybrid Room)

THE GREAT BARRIER-SPIT COMPLEX AT THE STOCKTON BAR, LAKE BONNEVILLE, UTAH

Paper number: T50-11
Program: Technical Sessions
Time: 3:55 PM – 4:10 PM

Authors

Abstract

An impressively large, late Pleistocene Lake Bonneville coastal constructional landform that separates Tooele and Rush Valleys near the hamlet of Stockton, Utah, was named the Great Bar at Stockton by G.K. Gilbert during field work for the Powell Survey in 1877. Gilbert’s field notes for July 14, 1877, provide the first known scientific description and sketch of the bar and adjacent terrain. It is clear, however, that Gilbert had at least known about the bar as early as 1872, as evidenced in his 1875 geological report for the Wheeler Survey covering field years 1871 and 1872 in which he mentions a gravel bar of great magnitude separating Rush and Tooele Valleys. Furthermore, it is quite possible that Gilbert had personally seen the bar in 1872 when he traveled to the nearby Ophir mining district for the Wheeler Survey. In addition to the one day in 1877, Gilbert’s field notes confirm that he spent seven days at the Stockton Bar locality in 1880 while he was in charge of the Great Basin Division of the newly formed U.S. Geological Survey. A full account of the coastal landform complex at and near the Stockton Bar appears in his U.S.G.S. Monograph 1 on Lake Bonneville.

Gilbert clearly defined the coastal landform terms that he used, carefully distinguishing beach, spit, barrier, bar, subaqueous bar, and other terms. The definitions of beach and spit have not changed significantly since the late nineteenth century, and his subaqueous bar is today referred to simply as a bar. Gilbert’s definition of barrier correlates with the modern term bayhead barrier, and what he called a bar is now termed baymouth barrier. Nevertheless, as a proper name for a distinctive individual example, the name Stockton Bar has been retained. The Stockton Bar is just one component of an assemblage of barriers and spits found at this location, which experienced considerable hydroisostatic effects. Available sediment from large lake-adjacent alluvial fans and extensive fetch from the north and northwest combined with the effects of isostatic adjustments to leave an impressive record of the history of the lake between its two most prominent shorelines, the Bonneville and Provo.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-370202

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