More than a pinch of salt

The unusual geology and ecology of the Dead Sea and the Great Salt Lake.

Holidaymakers on a first visit to the Dead Sea are invariably in for a surprise, those who enjoy swimming underwater in pools at home have great difficulty in just staying below the surface, this is because the Dead Sea contains 25 to 30% salt, compared to 4 to 6% in ocean water.  Similar readings have been recorded at Utah's Great Salt Lake in the United States where it is equally difficult to sink.

Lying low

The two Salt Lakes have very different histories.  The spectacular trench occupied by the Dead Sea and the Jordan River, which flows into it was created some 26 million years ago by an upheaval on the seabed at a time when the Mediterranean covered the holy land.  At 1300 feet below sea level, that Dead Sea is the lowest body of water on Earth.

The Great Salt Lake is of more recent origin, being the remnant of the glacial Lake Bonneville which can into existence 18,000 to 25,000 years ago.  Having shrunk, through evaporation, to 1/20 of its original size it now all like the Dead Sea has no outlet.  But Rivers still feed the lake, bearing minerals dissolved from surrounding rocks.  As the water evaporates the minerals remain, 60,000,000 tons of them, including magnesium lithium and pot ash.

Salt lakes are conveniently seen as barren, because they support no fish, but the Dead Sea is not completely dead, certain algae and bacteria are adapted to its salt rich environment.  The Great Salt Lake, to, has its single cell organisms most noticeably the algae that color the northern part of the lake pink.  There are also larger life forms, brine shrimp and flies, whose larvae develop in the water.  The shrimp are eaten by gulls and shrimp eggs are harvested for sale as tropical fish food.

This business is minuscule compared to trade in the lakes great mineral wealth, such as valuable pot ash used for fertilizer. The Dead Sea also yields potash, and the Israelis run health spas where tourists can code themselves in rich, black mineral mud. 

Did you know?

There is enough salt in the oceans to cover all the continents with a layer 490 feet thick.

Of the 92 natural elements, scientists have found around 70 dissolved in seawater.  They expect to find all the remaining elements one day as well.