Bierstadt Moraine EarthCache
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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 (visit link) 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: (visit link) 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.
The aim of this EarthCache is to become familiar with the till and sediments left behind by the glaciers of the Pinedale Glaciation. While hiking down the Bierstadt Moraine, you will be examining the material which makes up this moraine, as well as measuring the height of the moraine and the slope of the trail. It is imperative that you stay on the trail at all times! Please do not take shortcuts which could cause severe erosion of the hillside.
Glaciation in the Front Range of the Rocky Mountains is divided into roughly three “ages”: the pre-Bull Lake age of the middle & lower Pleistocene (beginning about 1.2 million years ago), the Bull Lake age of the upper & middle Pleistocene (lasting from about 120,000 - 300,000 years ago), and the Pinedale age of the upper Pleistocene (lasting from about 10,000 – 30,000 years ago).
The Bierstadt Moraine is a steep, lateral moraine which runs for about 3 miles on the north side of Glacier Creek. It is formed of till from the Pinedale age of glaciation. Note the large boulders in the moraine as you walk down the trail. Till of the Pinedale Glaciation is distinguished from the till of earlier ages by consisting of larger boulders with sharper edges and less weathering. These boulders may retain some of the polish and striations which were formed during their movement. Additionally, the moraines from the Pinedale Glaciation tend to have a sharper crest (see the crest about 100’ up the trail from the given coordinates), and thinner overall soils.
Take an elevational reading at the site of the given coordinates. From here, set up your GPS receiver to take a tracking log of your hike down the moraine. At the bottom of the moraine, at the parking lot for the Bierstadt Lake Trailhead, take a second elevational reading.
To log this EarthCache, send me an email with the answers to the following questions:
1.) What is the height of the moraine?
2.) Using your tracking log, and the height of the moraine, tell me the slope of the trail that you just walked.
3.) Describe to me in your own words a distinguishing feature of the Pinedale Glaciation which you found on your hike down the Bierstadt Moraine. This may include the crest of the moraine, above-ground boulders which you found on your hike down, or any other feature which attests to the relatively young age of this moraine.
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.
KellererLynn, K. 2004. Rocky Mountain National Park. Geologic Resource Evaluation Report. NPS D307, September 2004. Online at: (visit link)
Rocky Mountain National Park. Online at: (visit link)
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!
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