LAKE BONNEVILLE MAPPED

As the largest late Pleistocene lake in the now-desert basins of western North America, Lake Bonneville has been the object of scientific attention since 1849-50 when Stansbury realized the significance of benches high on neighboring slopes during his detailed survey of Great Salt Lake. Between 1867 and 1879, the great western field surveys of Hayden, Wheeler, King, and Powell all covered portions of the Bonneville basin, and the ancient lake received varying attention in the several resulting reports. G.K. Gilbert entered the scene in the early 1870s, beginning his studies of the paleolake with the Wheeler Survey, and continuing them with the Powell Survey after 1874. Topographic mapping of the Bonneville basin was largely divided between the Wheeler Survey on the south and King’s Fortieth Parallel Survey on the north. A natural extension of those mapping efforts was delineating the highest shoreline of Lake Bonneville, and the two groups undertook that enterprise separately. Gilbert followed the lake evidence regardless of survey domain. He published the first topographically based map of Lake Bonneville, at the approximate scale of 1:1,000,000, in an 1875 Wheeler volume. King’s (1878) similar, but somewhat smaller scale, map spans the fortieth parallel west to east from Lake Lahontan to Lake Bonneville. Some differences are evident in the placement of the Bonneville shoreline on the two maps despite King (1878) citing Gilbert (1875) as the source of the map information south of Utah Lake. King expressed irritation with Gilbert for extending his map into Fortieth Parallel Survey terrain, and Gilbert (1890) later disparagingly described King’s (1878) map as “approximate.” In 1882 Gilbert introduced the now-familiar, detailed page-size (1:3,170,000 scale) map of Lake Bonneville that he refined and reused as base maps for multiple purposes in his comprehensive Lake Bonneville monograph. Because of their size, detail, accessibility, aesthetic quality, and extensive use, those small scale maps have eclipsed the monograph’s 1:800,000 scale foldout map of the lake at its maximum extent. Furthermore, the accuracy of Gilbert’s Lake Bonneville maps is such that very few changes have been made in the lake’s delineation since their appearance.