Geologic Units |
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Quaternary alluvial deposits |
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Gravels and terraces on western Snake River Plain |
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Quaternary surficial cover, fluveolian cover on Snake River Plain, alluvial fans (Snake River Group) |
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Recent basalt lava |
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Pleistocene basalt lava |
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Pleistocene and Pliocene basalt lava and associated tuff |
| Map Key | |
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Geologic units with unit designation. |
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Normal Fault: certain; dashed where approximately located; dotted where concealed. |
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Thrust Fault: certain; dashed where approximately located; dotted where concealed. |
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Detachment Fault: certain; dashed where approximately located; dotted where concealed. |
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Interstate Route. |
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U.S. Route. |
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State Route. |
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Location of Rockwalk rock from the county. |
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Cities. |
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Feature location. |
Minidoka County
Minidoka County is entirely on the Snake River Plain, on the north side of the Snake River west of Minidoka Dam and Lake Walcott. Extensive irrigated farming of the North Side Tract occurs on alluvial soils between Minidoka, Rupert and Heyburn. To the north, across the Union Pacific mainline are Quaternary basalt lava flows, heading toward Craters of the Moon to the northeast. This country is empty sagebrush desert.
See discussion of Snake River Plain geology from Rocks, Rails and Trails.
P.K. Link, 10/02
Additional Reading
Rocks Rails and Trails: pages
The Snake River Plain-Yellowstone Hot Spot and its Effect on Drainage Patterns
Challis Volcanic Group & Intrusive
Lake Bonneville and its Flood
Disposal of Wastes at the Idaho National Engineering & Environmental Laboratory
References on Idaho Geology
Section 3, History of Eastern Idaho
Section 3, Chapter 8 -"Famous Potatoes" Agriculture & Irrigation
Section 6, Chapter 20 - Root Hog, Big Butte & Craters of the Moon
Click here to see a correlation of geologic units, and the associated time scale.
Click here for a printable version of this map.
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