Geology of Idaho The Snake River Plain
Idaho can be divided into 6 natural geologic regions, each with its own unique characteristics
Northern Rockies Clearwater Plateau Snake River Plain Owyhee- Bruneau Plateau Basin & Range Province Middle Rockies
The Columbia Plateau spills over into other states from Washington, even into 3 regions of Idaho
Columbia Basalts show many layers from many sequential flows
Clearwater Plateau Owyhee- Bruneau Plateau Snake River Plain These are the 3 regions of Idaho that share a volcanic origin by extension of the Columbia Plateau
Gently rolling hills and valleys; a thinly-spread grassland with some desert-like vegetation
Some cinder cones, erroneously called “buttes”, are located in this dry grassland
Rivers and their tributaries have left their impact on the plain
The Snake River is the main one, arising from Jackson Lake in Jackson Hole, WY, on the eastern slope of the Grand Teton range
It flows westward across the southern edge of the SRP. Over thousands of years it has eroded huge canyons in some places, like the Snake River Canyon near Twin Falls (below)
On the eastern edge of the SRP is found the Grand Canyon of the Snake River.
The deepest, most rugged part is called Hell’s Canyon, the deepest gorge in North America, 8000 feet below the surrounding mountain peaks
Hell’s Canyon lies at the foot of the Seven Devils Mountains (count them)!
Lewiston (L) and Clarkston (R) lie at the confluence of the Snake (back) and the Clearwater (bottom) Rivers
Lost River Range Lost River Sinks
The Lost Rivers flow out of the valleys of the Lost River Range and disappear into the ground of the Plain
The waters become part of the Eastern Snake River Plain Aquifer flowing to the Snake River on the west
The Snake and tributaries used to flood regularly through thousands of years
Now, dam systems control the flow
And create opportunities for agriculture
SRP Formation Volcanic activity Water erosion Sedimentation
Fissure flows
Leading to layered basalt formations
Numerous cinder cones (buttes)
And every volcanic formation you can think of located at
Located in the east-central part of the plain in a triangular area formed by Arco, Idaho Falls and Pocatello
There are many self- guided tours of the site as well as an interpretive center
pahoehoeCinder cones Aa Lava tubes
The Yellowstone Hot Spot is responsible for the heat that created all this volcanism
Water is down in the summer due to irrigation demands
Flooding is no longer a problem due to……
A series of dams to control flooding, create recreation, and provide irrigation water On June 6, 1976 the Teton Dam near Rexburg, Idaho failed during its initial filling. At 350 feet high, it was the largest dam break in US history and the damages reached $1 billion.
After the breach
This water has increased the value of the mixed volcanic-sediment soil to…….
Idaho Agriculture
Climate Mild and pleasant Summers sunny and warm with few cloudy days; winters cool and dry Precipitation averages 10 inches (25cm); semi-arid (quick thundershowers) Summer temp.= 81degrees (105 max) with cool evenings Winter temp.=13-35 degrees with snow in the mountains surrounding
From space
End of the road!