Annual Meeting

Aerial view of Hagues Peak and Lawn Lake in the Mummy Range in 1976. The Lawn Lake dam (built about 1905), visible at the lower right, catastrophically failed in 1982, sending a wall of water down the narrow alpine valley toward Horsehoe Park. Several campers lost their lives in the flood. Farther downstream, in Estes Park, water from the breeched dam caused the Big Thompson River to rise over its banks, causing extensive property damage to commercial areas of the city. Photograph by Jim Cole.

The spectacular alpine scenery of the Estes Park valley and Rocky Mountain National Park reflect the sum of geologic processes operating over nearly 2 billion years. Roadside locales and vistas afford numerous opportunities to explore aspects of geology, hydrology, geomorphology, and history that have contributed to the geologic story of the region. These landscapes have affected human activities in the past and will continue to influence us in the future. Topics planned for this excursion include:

• Uplift and erosional history of the Front Range, and why mountains exist.Silver Plume Granite — where it came from, how it got here, what it did along the way (and what does it have to do with Lumpy Ridge?).
• The oldest rocks of the Front Range — unraveling their stories of deposition, folding, metamorphism, and melting.
• Big Thompson flood of July 1976 — why did it happen, what did it do, and what does "hundred-year flood" mean, anyway?
• Colorado — Big Thompson Project — moving lots of water under the Continental Divide for lots of reasons.
• Glaciers, glaciation, and climate change in the last 2 million years.
• Roaring River debris fan and other effects of the catastrophic Lawn Lake dam failure.

The field trip will cover a subset of these topics based on weather, accessibility, and interests of the trip participants. All stops will be along roadways and will require only limited walking. Box lunches provided.

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A Photo Gallery:

 

 

 

 

 

 

Rock spires along the Continental Divide, near Bear Lake, in Rocky Mountain National Park. Vertical fractures have been enhanced by frost action and weathering during Quaternary ice ages. Horizontal banding shows light-colored granite intruded into metamorphic rocks. This is a popular rock-climbing area. Photo by Jim Cole in 1971.

Looking up the glacially carved gorge from Dream Lake, in Rocky Mountain National Park. Photograph by W.T. Lee in August 1916. U.S. Geological Survey Photographic Library.

Precipitous cliff walls of the east face of Longs Peak, as viewed from Chasm Lake, some 2,400 feet below the summit of the mountain. At 14,255 feet, Longs Peak is the highest peak in Rocky Mountain National Park. It is a prominent landmark visible from Denver and the surrounding Great Plains. Photograph by W.T. Lee on July 22, 1916. U.S. Geological Survey
Photographic Library.

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Please contact Lisa Pinsker at lmp@agiweb.org if you have anything to add to this page.