Geologic Units

Quaternary surficial cover, fluveolian cover on Snake River Plain, alluvial fans (Snake River Group)
Quaternary alluvial deposits
Pliocene and Upper Miocene stream and lake deposits (Salt Lake Formation, Starlight Formation, Idaho Group)
Eocene sedimentary rocks
Triassic sedimentary rocks
Jurassic sedimentary rocks.  
Permian and Pennsylvanian sedimentary rocks
Ordovician sedimentary rocks
Silurian sedimentary rocks 
Devonian sedimentary rocks

  Map Key
Geologic units with unit designation.
Normal Fault: certain; dashed where approximately located; dotted where concealed.
Thrust Fault: certain; dashed where approximately located; dotted where concealed.
Detachment Fault: certain; dashed where approximately located; dotted where concealed.
Interstate Route.
U.S. Route.
State Route.
Location of Rockwalk rock from the county.
Feature location.

Bear Lake County

In Idaho's southeast corner, Bear Lake County is with both the Idaho-Wyoming thrust belt and the Basin and Range province. Drilling for oil was big news here in the late 1970s and 1980s, and it will happen again. Rich phosphate ore of the Phosphoria Formation allowed development of mines in Georgetown, Paris and Montpelier through the 20th century.

For more detail on the geology of Bear Lake County see the text from Rocks, Rails and Trails Also see the Fortsch and Link field trip guide in Geologic Guidebook to eastern Idaho.

P.K. Link 10/02

Additional Reading

Rocks Rails and Trails: pages:
Introduction to the Geology of South & East Idaho
Introduction to Geologic Diagrams
Geologic cross sections
Relations between Geology, Topography and Drainage Systems in Idaho
Drainage and mountain range map for eastern Idaho
Table of Geologic Events in Southern Idaho
Drainage Systems, Rails and Trails
Geologic Provinces along the Oregon Trail
Rocks of the Eastern Idaho Mountains
Southeast Idaho Phosphate Mining
The Thrust Belt of Southeastern Idaho
Views of Thrust Faults
Basin and Range Faulting
References on Idaho Geology
Section 3, History of Eastern Idaho
Section 3, Chapter 8 -"Famous Potatoes" Agriculture & Irrigation
Section 4, Chapter 9 -The Bear Lake Valley
Geology of the Soda Springs Area

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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