Introduction to Geology Santaquin Field Trip

On September 12, 2002, subdivisions on the outskirts of Santaquin were struck by debris flows that caused extensive damage. The debris flows - essentially mudlows, but with sand, cobbles and boulders mixed with the mud - resulted from intense rainfall on hillsides that were burned by the Mollie forest fire in the fall of 2001. Much of the debris flows remain, and we regularly take GEOL 1010 to see them on extra credit field trips. Some photographs of the area are below. For more information on the debris flows, see the Utah Geological Survey page on them.

Follow this link for a map to the meeting location for this field trip, the Santaquin Ace Hardware.

The first four photos illustrate the impact of one the flows on a subdivision. The photographs were taken by the U.S. Forest Service, and higher resolution versions are available on the UGS site.

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The following images are from field trips to the affected area.

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Looking up towards the mountains at the flow that did the damage to the homes in the photos above.


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The view down the flow that inundated the subdivision.


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This flow stopped on the edge of the subdivision and did minimal damage.


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The flows contain large boulders, as can be seen in this image.


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One of the flows eminated from this eroded gully in the mountains.  The flows eroded mud, sand, gravel and boulders from gully bottoms and carried the debris into the flatter areas below the gullies - and in some cases into developed areas.