| Wave-cut terraces (or benches) on the Promontory Mountains. These step-like features formed by waves eroding the shoreline during periods when lake levels were stationary between other periods when water surface levels of ancient Lake Bonneville were rising or falling during the Quaternary Period. Wave-cut terraces can be seen along the lower mountainsides throughout the Great Basin region. During periods when water levels were high, the peaks of the Promontory Mountains were islands in the great freshwater lake. The modern Salt Lake is a remnant of the original great Lake Bonneville. The last high-standing level of the lake was about 14,000 years ago (NPS, 2006; Utah Geological Survey, 2010a,b). |
