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Twin Falls Area
Twin Falls is located on the south side of the Snake River Canyon in an area of Pleistocene lake beds. The soil is deep and rich except in areas scoured by the Lake Bonneville Flood on the north side of the canyon where the volcanic bedrock or fields of boulders or "petrified watermelons" remain.

 ."As we were going on our way back to camp we discovered what we took to be a heavy dust rising east of us which we concluded was a band of Indians....A little later we discovered that it was only a fog or mist raising from the water pouring over a falls on the Snake River"(Shoshone Falls)" Diary of Oregon Trail Pioneer, John C. Hilman, August,1862.

The canyon of the Snake River exposes Miocene rhyolite underneath the cover of basalt lava. At Shoshone Falls and Twin Falls the Snake River cascades over this rhyolite in waterfalls carved during the catastrophic Lake Bonneville Flood about 14,500 years ago. Shoshone Falls are 212 feet high, higher than Niagara.

The dry waterfalls or alcoves (blue Lakes alcove) north of the Snake River were also carved during the Bonneville flood.

(top left) Old Hansen suspension bridge over the Snake River, opened in 1919. It was originally two lanes, but as cars became wider the bridge was reduced to one lane. The old bridge was replaced with the present concrete bridge in 1966. Abe Lillibridge collection, Idaho State University.

(top center) Snake River Canyon at Murtaugh Bridge, looking west, downstream.The town of Murtaugh is immediately to the left of the view. Note the scoured Bonneville Flood path, on which there is not enough soil to grow even irrigated crops. Caldron Linn is just upstream (to the right) from here, (July, 1989).

(top right) Aerial view looking west, (June, 1991), of the Lake Bonneville Flood path near Murtaugh east of Twin Falls. The south branch of the flood followed the Snake River Canyon here while the farmland to the north of the river was not eroded by the flood waters. The north branch of the flood passed through the scoured basalt in the far right distance. The Hiline Canal can be seen to the south of the river.

(mid center) Caldron Linn, a narrow waterfall along the Snake River west of Milner Dam. The name was chosen by the Hunt Party of Astorians,who in 1811 abandoned their attempt at navigating the Snake at this place.The word "Linn" is an old Scottish word for waterfall. The boiling waters were likened to a caldron (cauldron). During low water a person can almost jump over the river at the narrowest point, (March, 1993).

(mid right) Twin Falls, 125 feet high, before 1910. A power plant now blocks the right (south) channel. Abe Lillibridge collection, Idaho State University Library.

(bottom right) Shoshone Falls in one of the rare times of high water flow, (May, 1983). The falls are cut in rhyolite lava beneath the basalt cap of the Snake River Plain. Photo was taken near the site of a hotel built for railroad visitors from Shoshone in1886. This was replaced by a larger hotel in 1890 which, in later years, was served from Twin Falls by an electric interurban line.