In mid-April, 2014 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured a striking picture of Utah’s Great Salt Lake. The image was captured on April 17, a sunny spring day.
The Great Salt Lake sits near the center of this image, with the northern arm appearing bluish-gray while the southern arm is colored bright green. A railroad causeway runs east to west across the lake, and restricts free flow of water between the two arms, resulting in significantly different aquatic environments. The water north of the causeway typically has about twice the salinity of the rest of the lake, and the bacteria and algae living there are specialized for a strongly saline environment. South of the causeway the salinity is lower – allowing heavy growth of green algae.
The Great Salt Lake is a remnant of Lake Bonneville, which was carved by glaciers and stretched across most of Utah and parts of Idaho and Nevada between 32,000 and 14,000 years ago. As the glaciers retreated and precipitation to the region decreased, the glaciers that fed Lake Bonneville by their melt water disappeared, leaving the lake to dry.
What remains of Lake Bonneville, besides the Great Salt Lake, is the Bonneville Salt Flats, a vast salt pan which can be seen lying across the arid land in the west. The snow-covered mountains to the east of the Great Salt Lake are the Wasatch Range.