Lake Missoula: Thompson Falls to Spokane

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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Acknowledgement

I need to make it crystal clear that none of this is my own research. The pictures on this and associated pages were taken on a GSA field trip in 2003 led by Norm Smyers of the U. S. Forest Service and Roy Breckenridge of the Idaho Geological Survey, and the interpretations presented here are largely those of Dr. Smyers and Dr. Breckenridge as presented on the field trip and its guidebook. I thank Dr. Smyers and Dr. Breckenridge for an outstanding field experience.


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Thompson Falls

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3.1 Beaver Creek

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3.2 Cabinet Gorge Dam

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##The gorge here is a miniature version of Devils Gate, Wyoming. The flat terrace across the river is not bedrock but glacial deposits. A bedrock spur projecting into the valley was buried and then incised by the river.
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3.3 Lake Pend Oreille

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Above: panorama of Lake Pend Oreille, from south at left through west (center) to north (at right). The Clark Fork River enters the lake out of view to the left and the lake drains through the valley left of center, where a moraine impounds the lake. The distant hills left of center blocked the ice lobe.  The ice tongue that dammed Glacial Lake Missoula was no narrow sliver. It filled this entire valley and extended about halfway up the hills on the left syline.

##Mouth of the Clark Fork River where it enters Lake Pend Oreille. The high peak at far left is Green Monarch, which calls to mind some sort of weird mutant butterfly. The notch just inside the picture was possibly an ice-marginal drainage.
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3.5 Farragut State Park

##Why is a state park in Idaho named after an admiral? Because it used to be a Navy training center during World War II. The Navy still has a facility in nearby Sandpoint where they test equipment. The roads in the park have the characteristic look of a military base layout.
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##The military has an unerring instinct for sand and gravel; in this case, a moraine. This is the moraine that impounds Lake Pend Oreille. It can be seen abutting the mountains at center.

It's not that the military likes sand and gravel so much, but they tend to locate facilities on otherwise marginal and little used land.

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Rathdrum Prairie

##Left and below: general views of Rathdrum Prairie.
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Below: the grazing illumination nicely brings out current ripple marks on the Rathdrum Paririe.
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##Closing the circle. The hill at right is the north side of Ross Point, the first stop on the trip.
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Spokane Aquifer

##The flood gravels are very porous and serve as the principal aquifer for the Spokane area. This gravel pit extends below the water table but dredges continue to extract gravel from underwater.
##The very abundance of the Spokane aquifer means paradoxically that little is known about it. Most wells are shallow, so little is known of the depth or stratigraphy of the aquifer.

Geological Society of America Channeled Scablands Trip, 1994

Spokane to Soap Lake
Soap Lake to Chelan
Chelan to Othello
Othello to The Dalles
The Dalles to Seattle

Geological Society of America Glacial Lake Missoula Trip, 2003

Spokane to Missoula
Missoula to Thompson Falls

Other Missoula Floods Pages:

Wallula Gap
Frenchman Coulee


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Created 9 November 2003, Last Update 01 July 2012

Not an official UW Green Bay site