South Rim of the Great Basin

The low ridge closing this valley to the south is the south rim of the Great Basin — the closed bowl whose waters find no way to the sea. In the Ice Age it brimmed with Lake Bonneville, a freshwater inland sea more than a thousand feet deep and some twenty thousand square miles wide, whose old shorelines still ring the mountains like bathtub lines. Fifteen thousand years ago the lake broke through Red Rock Pass in Idaho and drained toward the Pacific. Great Salt Lake, Utah Lake, and Sevier Lake are the puddles it left behind.

What the plaque says

The low ridge at the south end of this valley forms the south rim of the Great Basin, which in prehistoric times was the bed of a vast body of water now referred to as Lake Bonneville. It was so named in honor of Captain Benjamin L. E. Bonneville, who in 1833 directed the first scientific exploration of its largest remnant—Great Salt Lake. Lake Bonneville extended 350 miles to the north and was in places 145 miles wide, with a maximum depth of 1050 ft. Its shoreline is clearly discernible on the mountain slopes fringing the basin. Through the Red Rock Pass in what is now southern Idaho, the lake drained into the Pacific Ocean, its waters flowing down the Portneuf, Snake, and Columbia Rivers. Of this large body of water, the Great Salt Lake, Utah, Sevier, and other small lakes remain. Lying in the lowest part of the lake bed and having no outlet, Great Salt Lake has become the “Dead Sea” of the Western Hemisphere.

Where it stands

Worth the stop nearby

• Kolob Canyons — 9.0 mi
  The quiet, uncrowded back door to Zion National Park
• Cedar Breaks National Monument — 18 mi
  A 2,000-foot-deep amphitheater of vivid orange and red rock
• Brian Head — 19 mi
  Utah's highest town — a ski-and-bike base camp at the top of Parowan Canyon
• Zion National Park — 21 mi
  Towering sandstone cliffs that glow like fire at sunset

More markers nearby

• Fort Kanarra — 3.0 mi
• Fort Harmony — 8.0 mi
• Southern Indian Mission — 8.0 mi
• Ellen (Nellie) Pucell Unthank — 8.4 mi