Glaciation at Bear Lake

Rocky Mountain National Park is located west of Estes Park and north and east of Grand Lake. This is a fee area of the National Park Service, and costs $30 per vehicle. This fee is covered in the Rocky Mountain National Park Annual Pass, the Rocky Mountain National Park/Arapaho National Recreation Area Annual Pass, and the America the Beautiful Pass. Please see the following website http://www.nps.gov/romo/planyourvisit/feesandreservations.htm for the entire fee schedule. The park is open 24 hours a day, 365 days a year. Road and Trail Conditions and Closures can be found at: http://www.nps.gov/romo/planyourvisit/road_conditions.htm. Recorded information for the condition of Trail Ridge Road can be found by calling (970) 586-1222. Please remember that all geologic features within the borders of Rocky Mountain National Park are protected by law, as are all natural and historic features. Please do not disturb, damage, or remove any rocks, plants, or animals.

Parking is located at the Bear Lake Trailhead, or you can park at one of the several shuttle bus parking lots and take the shuttle to Bear Lake. This EarthCache is reached by a paved asphalt path, and is fully accessible.

To the west, towards Hallett Peak and Flattop Mountain, you can see the U-shaped valleys and bowl-shaped cirques that are evidence of glacial effects on this landscape.

There have been several episodes of glaciation in the upper reach of this river valley. Most of the sculpting of the mountains in front of you was conducted during the Pinedale age of glaciation. This was the third of the three primary glacial periods which were to carve the mountains of the Front Range.

Ice from the glaciers at this time was hundreds of feet thick. When it moved down the valleys, it pushed everything in its path like a huge U-shaped bulldozer. Valleys were smoothed, widened, and deepened. Rock and soils were picked up, mixed together, and deposited as till. Often, this material was carried several miles from its origin.

At the end of the Pinedale Glaciation, a warming trend began during which the remains of the Pleistocene glaciers melted. When Neoglaciation (the “Little Ice Age”) began around 3,800 years ago, some of the high elevation cirques at the heads of the valleys were again occupied, but with much smaller glaciers. Tyndall Glacier, found in the cirque between Hallett peak and Flattop Mountain, is one of the remaining active (moving) glaciers in the Park.

To receive credit for this EarthCache, send me an email with the answers to the following questions:

1.) How long ago were the glaciers active?

2.) How deep was the ice in the Bear Lake Basin?

3.) How many active glaciers remain in Rocky Mountain National Park?

Please consider posting photos of yourself, or the local geology, when you log this EarthCache. Photos can be an additional rewarding part of your journey, but posting them is not a requirement for logging this EarthCache, and is strictly optional.

The above information was compiled from the following sources:

2004. Rocky Mountain National Park. In Harris, A.G. et al., editors. Geology of National Parks, Sixth Ed. P. 337-356. Dubuque, Iowa: Kendall/Hunt Publishing Company.

Cole, J.C., and Braddock, W.A. 2009. Geologic map of the Estes Park 30’ x 60’ quadrangle, north-central Colorado: U.S. Geological Survey Scientific Investigations Map 3039, 1 sheet, scale 1:100,000, 1 pamphlet, 56 p.

Colorado Geological Survey. 2003. Messages in Stone. Matthews et al., editors. Denver, Colorado.

KellererLynn, K. 2004. Rocky Mountain National Park. Geologic Resource Evaluation Report. NPS D307, September 2004. Online at: http://www.nps.gov/romo/parkmgmt/upload/romo_geo_overview.pdf

Rocky Mountain National Park. Online at: http://www.nps.gov/romo

Informational signage at the site.

Rocky Mountain National Park was most helpful in the background discussion, aid in the choosing of sites, and review of this EarthCache. My thanks to the Park for allowing the placement of this EarthCache!