The Great Salt Lake, the largest salt lake in North America, is featured in this spectacular, south-southeast-looking, low-oblique photograph. The lake is a remnant of a much larger prehistoric lake that covered portions of present-day Idaho, Nevada, and Utah 12 000 years ago. Dependent on precipitation, the Great Salt Lake fluctuates in size seasonally and yearly. This photograph shows a water level higher than usual because of above-normal precipitation in preceding years. A railway causeway bisects the lake—the northern, greenish half with a higher concentration of salt is much shallower than the bluish southern half. Visible counterclockwise from the upper left corner are the snowcapped Wasatch Range; center-pivot irrigation fields; and the Great Salt Lake Desert, once the floor of ancient Lake Bonneville.