From a mountainside overlooking Utah's Great Salt Lake, a time traveler turning back the clock 20,000 years would watch a dramatic transformation of the landscape. The shallow, salty lake below would swell into an immense body of fresh water, at one point reaching nearly 1,000 feet (305 meters) deep and covering more than 10 times the lake's modern area. Mountain ranges would become islands, and the new shoreline would move far beyond its current boundary.