Juke Box trench: A valuable archive of late Pleistocene and Holocene stratigraphy in the Bonneville basin, Utah

A backhoe trench in deposits of Pleistocene Lake Bonneville and Holocene wetlands below the mouth of Juke Box Cave, near Wendover, Utah, provides an excellent view of the late Pleistocene and Holocene geologic history of the area. The following stratigraphic units are exposed (ascending): preBonneville gravel (fluvial or lacustrine) and oolitic sand (ages greater than 30,000 yr B.P.); Lake Bonneville marl (30,000 to ~13,000 yr B.P.); an unconformity stratigraphically above the Bonneville marl marked by lacustrine gravel of probable Gilbert-episode age (~11,500 yr B.P.); and poorly sorted sand and carbonate mud deposited in post-Bonneville spring-fed wetlands. The wetland deposits include layers of poorly sorted sand, peat composed of bulrush remains and other organic-rich muds, and the Mazama volcanic ash (~7600 yr B.P.). Four calibrated 14C ages suggest the wetland deposits span nearly the entire Holocene, from about 10,700 to at least 1200 yr B.P. The spring and wetland are now dry.