Great Salt Lake serves as a striking visual marker for astronauts orbiting over North America. A sharp line across its center is caused by the restriction in water flow from the railroad causeway. The eye-catching colors of the lake stem from the fact that Great Salt Lake is hypersaline, typically 3–5 times saltier than the ocean, and the high salinities support sets of plants and animals that affect the light-absorbing qualities of the water. Space Station astronauts have recorded the decline in lake levels in response to a regional 5-year drought taking both detailed views and broad views of the entire lake. As lake levels have declined the salt works have become islands in the middle of a dry lakebed.
The Great Salt Lake of northern Utah is a remnant of glacial Lake Bonneville that extended over much of present-day western Utah and into the neighboring states of Nevada and Idaho approximately 32,000 to 14,000 years ago. The north arm of the lake, displayed in this astronaut photograph from April 30, 2007, typically has twice the salinity of the rest of the lake due to impoundment of water by a railroad causeway that crosses the lake from east to west. The causeway restricts water flow, and the separation has led to a striking division in the types of algae and bacteria found in the north and south arms of the lake.
If Lake Natron, in Africa’s Great Rift Valley, had a color theme, it would be pink. The alkali salt crust on the surface of the lake is often colored red or pink by the salt-loving microorganisms that live there. Also, the lake is the only breeding area for the 2.5 million Lesser Flamingoes that live in the valley. These flamingoes flock along saline lakes in the region, where they feed on Spirulina, a blue-green algae with red pigments. This mosaic of photographs of the southern portion of Lake Natron shows the largest open lagoon area, and island mud flat, and a large area of pink salt crust. The colors show the actual colors viewed by the astronauts. Each time the lake is photographed, there are differences in the pattern of its salt crust, and the red colors of the blue-green algae and bacteria on the surface of the crust.
A rim of crystal salts surrounds Lake Qarhan, the largest salt lake playa in China and a significant source of minerals, including table salt and potassium for fertilizer.