Clark Leming, age 13., of Sarasota, Fla., for his question:
What causes inland salt lakes to form?
When the cruel ice Ages gripped the world, salty lakes shut off from the sea were very rare. As the glaciers melted, the land was paddled with countless lakes. But their waters were fresh. Salt lakes formed later when the climate became warm arid the air became drier. Changes in the face of the earth also helped to form these salty puddles.
The Caspian Sea is the biggest lake in the world, and its inland waters are almost as salty as the salty sea. The steamy waters of the land locked Dead Sea are 100 times saltier than ocean water. We have many salty lakes in North America, especially in the arid region between the Sierra Nevada and the Rockies. In California, there is a little salt lake called the Salton Sea. Farther north, in Utah, is the famous Great Salt Lake where the waters are six times saltier than the ocean.
The basin of a lake is a trough or depression in the land. Water from rains and snows, streams and rivers drains in to fill the hollow. As the water 1eve1 rises, it finds creeks or outlets to lead it to some river and finally to the sea. It is constantly filling with fresh river Water and overflowing.
The so-called fresh water of lakes and rivers is not salty to the taste. Nevertheless, it contains traces of salty minerals leached from the land. If tons of this fresh water evaporates, the salty chemicals stay behind and We can taste them. This is what causes the brine in most salt lakes. At one time, Great Salt Lake was a huge lake of fresh water, filling and draining to the sea like a vast, overflowing bathtub.
This was long ago, when the climate was cooler and more moist. The surface of that aricient Lake bonneville was 1000 feet higher than the present salty lake. It was high enough to find an outlet through one of its northern arms where it overflowed through Red Rock Pass to the Snake river which joins the wide Columbia on its way to the sea. The climate became warmer and drier and the level sank. The water evaporated and became saltier. The lake shrank, and its surface dropped too low to find an outlet in the high cliffs around it. Nowadays, the Great Salt Lake loses more water by evaporation than it gains from its streams.
Other salty lakes are formed by changes in the land. The Salton Sea is a little puddle in a large trough that dips toward the Gulf of California. But in recent years, the busy Colorado river dumped piles of debris which shut of this channel to the sea. The Salton Sea gains less water than it 1oses to the thirsty air above it. The Caspian Sea once fed the Mediterranean, but its waters became trapped by earth changes. This largest of the world's lakes is still shrinking.