Cheryl A1 Muservy, age 12,
How big was the ancient Lake Bonneville?
Trappers and traders may have found it before, But Captain Bonneville's expedition of 1833 described the big salt lake and put it on the map. He named it Lake Bonneville Kit Carson and John Fremont explored it ten years later. In 184'7, the hard working Mormons arrived to turn the desert area into flourishing farmlands. By then, the stretch of water was called the Great Salt Lake,
Such fascinating territory attracted geologists and surveyors. Why the big lake was changing before their very eyes. In the dry weather it shrank a third of its size. When snows melted from the nearby Rockies it swelled and rose 16 inches. Its waters were five or six times as salty as the sea ‑ and getting saltier„ For the lake has no outlet to the ocean. It is fed by the Jordan, Bear, Weber and other rivers. The sun dries up pure vapor from its surface, leaving the salt behind. In a hundred years, the lake lost 100 square miles of its area,
Surely such a changeable lake must have an interesting past. Was it once bigger, smaller, fresher or more salty? The evidence of the past was found carved and built into the rocks of a wide area. Here once stood an ancient lake of fresh water ten times larger than Great Salt Lake. It was named Lake Bonneville in honor of the captain who described the salty lake that remains.
Thousands of years ago, Lake Bonneville covered an area of over 19,000 square miles. That is almost one quarter of the area of the state of Utah, In area, Lake Erie and Lake Ontario together are three‑quarters the size of the ancient lake. It was 1,050 feet deep, almost as deep as Lake Superior.
The waters of the ancient lake were fed by snows from the Rockies but they had an outlet to the sea. Water from the lake flowed through Red Rock Pass into the Snake river, The Snake joined the mighty Columbia and waters of Lake Bonneville were carried on to empty into the Pacific ocean. Through the Ice Ages the climate and the geography of the land were changed. At one time, an arm of the sea crept over much of western Utah. Lake Bonneville began to shrink and it lost its outlet t o the sea.
As it retreated from its beaches, the ancient lake left its marks, On the mountainsides where it once lapped there are traces of seventeen different water levels. There are sandbars of ancient shores, water=smoothed cliffs and deltas The Great Salt Lake, still the biggest lake west of the Mississippi, is all that remains. Its area is about 20000 square miles, it is from 15 to 18 feet deep, 75 miles long and about 50 miles wide. But it is only a ghost of ancient Lake Bonneville that once covered ten times that area to a depth of about one fifth of a mile.