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20: Geology of the Snake River Plain Big Southern Butte Goodale or Jeffrey's Cutoff Toponce Stage Line and Root Hog Atomic City Idaho National Engineering & Environmental Laboratory Snake River Plain Aquifer Big Lost River Playas Arco Lost River Range and the Big Lost River Valley Craters of the Moon |
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| Morning commuter buses approaching CFA (central Facilities Area) at the Idaho National Engineering Laboratory, 7 a.m., September 15, 1992. East and Middle Buttes rise out of the sagebrush desert in the background. View looks east. | |||
| Sidebars: Idaho and Federal Dollars |
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Map
of the east-central Snake River Plain.
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Geology
of the Snake River Plain
The Snake River
Plain contains Pleistocene basalt and interbedded sediment in the upper few
hundred feet. The Snake River Plain Aquifer, the key to southern Idaho's agricultural
economy, mainly consists of basalts and interbedded sediments, deposited in
Pleistocene time (the last 2 million years). The underlying rhyolite does not
seem to be a major aquifer because many of the pore spaces are filled with chemical
precipitates. Within basalts, permeable zones are mainly the tops and bottoms
of lava flows, with columnar jointing providing vertical transmission of water.
