In the Jordan rift valley, the continents of Africa and Asia are pulling apart from each other, and the land in between has been subsiding for millennia. The sinking has created the Dead Sea.
The complex of Jordanian salt evaporation ponds at the southern end of the Dead Sea has expanded significantly over the past dozen years. The western margin of the salt ponds marks the Jordan-Israel border. In August 1989, when the crew of Space Shuttle mission STS-28 photographed the region, the northern extension did not exist and the large polygonal ponds in the northwestern and northeastern sectors had not been subdivided. In the view taken by the STS-102 crew in March 2001, one can see that there has also been expansion at the southeastern end, and that levees now segment the northeastern wedge into four ponds.
This detailed astronaut photograph shows the salt ponds of one of Africa’s major producers of soda ash (sodium carbonate) and salt. Soda ash is used for making glass, in metallurgy, in the detergent industry, and in chemical manufacture. The image shows a small part of the great salt flats of central Botswana known as the Makgadikgadi Salt Pans.
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.
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.