Transcript Geology of Idaho - District 273 Technology Services

Geology of Idaho
The Snake River Plain
Idaho can be divided into 6
natural geologic regions, each
with its own unique
characteristics
Clearwater
Plateau
Northern Rockies
Snake River Plain
OwyheeBruneau
Plateau
Middle
Basin &
Range
Province
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
Snake River Plain
OwyheeBruneau
Plateau
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 selfguided tours
of the site as
well as an
interpretive
center
pahoehoe
Cinder 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!