Mountain Home, ID, Library
The [Ira B.] Perrine Memorial Bridge over the Snake River on US93 at the northern edge of Twin Falls. The current bridge, completed in 1967 using a steel arch, replaced an earlier cantilever bridge from 1927 to 1976. [See links below for more history.]
A look west under the edge of the bridge and down the Snake.
[Click once to enlarge.] But because the enlargement is still not large enough, here's a transcription.
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"Snake River Plain Geology" Plaque Transcription
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The Snake River flows through one of the greatest volcanic plains in the world. This 400-mile-long crescent-shaped plateau extends from southwestern Idaho, east to the Idaho-Wyoming border. In cross section, it is a depression filled with layers of rock over 5,000 feet thick.
During the past 17 million years fractures opened in the earth allowing hot molten lava to pour out. The last of the lava flows in the Snake River plain occurred only 2,000 years ago. The basalt lava flows in the Snake River Plain were generated by hundred of "shield" volcanoes. Highly fluid lava flowed from the cracks in the earth's surface and spread out to creat a gradual curved feature with the appearance of an ancient soldier's shield.
Eventually the Snake River flows through cracks in the basalt lave flows caused by cooling of molten rock. Over time, these cracks enlarged to create the canyons we see today.
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The Bonneville Flood -- An Ancient Lake Dies, A Canyon Grows
About a million years ago, a gigantic lake about the size of Lake Michigan, covered roughly 20,000 square miles of northern Utah, eastern Nevada and southern Idaho. Lake Bonneville was former by a natural rock barrier at Red Rock Pass in eastern Idaho but had no river outlet to the sea.
Approximately 11,000 years ago--yesterday in geological terms--rainfall and snowmelt gradually raised the level of the lake until the natural dam collapsed. The entire lake came crashing through the Snakwe River Canyon, causing the Great Bonneville Flood.
The tremendous amount of water that ravaged the canyon scoured rock loose from the canyon walls, created whirlpool-eroded alcoves and deposited gravel bars hundreds of feet high along gthe Snake River Canyon.
The Bonneville Flood lasted about six weeks, but water coninued to flow from the remains of the lake for a year. A 350-foot-high wall of water raced through the canyon at 70 milles per hour. In that time 380 cubic miles of water flowed down the Snake River. Today, Utah's Great Salt Lake is all that remains of Lake Bonneville.
To get a perspective of the flood, the canyon at the Twin Falls Perrine Bridge is about 480 feet deep. Before the flood began, the river bottom was at the thin dirt layer visible on the north canyon wall about halfway down, near the bottom bridge support.
The bridge would have been under about 10 feet of water. Rock and dirt cascading downstream chiseled out the lower part of the canyon in just a few weeks. No flooding occurred above this area on the south side of the river as evidenced by the topsoil in the farm fields.
On the north side of the river water overflowed the canyon for miles and scoured the soil off the rock, then flowed back into the canyon just east of the bridge at Blue Lake County Club. The eddy created by the confluence of the river and the flooding water coming from the north, gouged the canyon wider. This created a perfect spot where centuries later Twin Falls pioneer Ira B. Perrine developed the region's first farm in the 1880s.
Shoshone Falls, pronounced Show-Shown by the locals rather than Show-Show-Nee as in the Indian tribe.
The height of the falls is 212 feet, and it is oft-times called the "Niagra Falls of the West."
One might make a case for there being more than two, or twin, falls.
But, if one looks at photos from the late 1800s, there was more water and fewer seemingly additional falls.
What follows are more photos of the falls -- tho not necessarily in the order in which they were taken.
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Links:
- The Perrine Memorial Bridge and its predecessor
- Wikipedia article on Showhone Falls
- Southern Idaho Tourism [Council] history of Shoshone Falls
T 1 May Actual Route: Burley bd - Burley Lib - Kimberley - Twin Falls - Perrine Memorial Bridge - Twin Falls Walmart
W 2 May Actual Route: Twin Falls Walmart - Twin Falls Lib - Shoshone Falls - Buhl - Miracle Hot Springs RV Park
Th 3 May Actual Route: Miracle Hot Springs RV Park - Hagerman Fossile Beds Natl Monument - Bliss - Gooding - Glenns Ferry - Three-Island Crossing State Park
F 4 May Actual Route: Three-Island Crossing State Park - Mountain Home Walmart
Sa 5 May Actual Route: Mountain Home Walmart - Boise Library - State St Walmart
Su 6 May Actual Route: State St Walmart - Ustick Br/Boise Library - Ontario, OR, Walmart
M 7 May Actual Route: Ontario, OR, Walmart - Ontario Lib - Fruitland, ID - Weiser - Cambridge - Mundo Idaho RV Park
T 8 May Actual Route: Mundo Idaho RV Park - New Meadows - Pollock - Canyon Pines RV Park
W 9 May Actual Route: Canyon Pines RV Park - Riggins - Grangeville - bd near Cottonwood
Th 10 May Route: bd near Cottonwood - Craigmont - Lapwai - Lewiston
Finding Campgrounds:
- RV Campgrounds from TrailerLifeDirectory.com
- Family Camping Directories from Woodalls.com
- Free campsites website
- Info on finding BLM Campgrounds
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