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Posted by on Jan 27, 2016 in Tell Me Why |

Why Is the Great Salt Lake Salty?

Why Is the Great Salt Lake Salty?

You don’t need an air mattress to float on the surface of the Great Salt Lake in Utah. The water is so salty that you cannot sink in it. Great Salt Lake wasn’t always salty. Many, many years ago, a much larger, freshwater lake existed there.

But less and less fresh water flowed into the lake, and much of it evaporated. The lake grew smaller and became salty. This is because the water that evaporated left behind the salt it had dissolved from the rocks and soil on its way to the lake. As a result, Great Salt Lake today is eight times saltier than the ocean.

Great Salt Lake is the remnant of Lake Bonneville; a great ice Age Lake that rose dramatically from a small saline lake 30,000 years ago. The most conspicuous reminders of Lake Bonneville are the ancient terraces etched into the landscape along the lake’s former shorelines. The terraces were eroded by wave action and are relatively flat areas that follow a contour line.

Look south from Buffalo Point for an outstanding view of Lake Bonneville terraces carved into the island as high as a thousand feet above the Great Salt Lake’s surface. After the ice age the earth’s climate became drier and Lake Bonneville gradually receded to form Great Salt Lake.

Great Salt Lake is too saline to support fish and most other aquatic species. Several types of algae live in the lake. Brine shrimp and brine flies can tolerate the high salt content and feed on the algae. Brine shrimp eggs are harvested commercially and are sold overseas as prawn food.

The oft maligned brine flies do not bite or land on people and are the primary food source for many birds that migrate to the lake. For most of the summer brine flies form a ring around the entire shoreline and rarely venture more than a few feet from the water’s edge. Biologists have estimated their population to be over one hundred billion.

Great Salt Lake draws people for a variety of recreational experiences and to enjoy what John Muir called “one of the great views on the American Continent.”

Bridger Bay Beach on the north end of Antelope Island is perhaps the nicest beach on the entire lake. The beach is a two-mile long, hundred yard wide expanse of white oolitic sand. Oolitic sand is actually formed in the lake and is made up of concentric layers of calcium carbonate (lime).

Look closely at the sand: most grains are smooth and perfectly round. Bridger Bay is where many people come to float like a cork because you cannot sink in the Great Salt Lake. To lie back and float upon the lake with only the sound of the gulls overhead is a unique experience unlikely to be forgotten.

Content for this question contributed by Bonnie Bentley, resident of Ludlow, Hampden County, Massachusetts, USA