Week 3 - Glaciers

Arapaho Glacier and South Arapaho Peak (13,397'), courtesy of protrails.com (2018)

My travels this week bring me on a hike to Arapaho Glacier, Colorado’s largest glacier in the Colorado, located in the Indian Peaks Wilderness. It is between the North Arapaho Peak and South Arapaho Peak and considered the primary source of water for the Boulder Watershed. It is approximately .25 miles long and .5 miles wide. The glacier covers nearly 60 acres and its accumulation zone is estimated to be 200 feet thick. The hike is a moderate-strenuous trail and is almost 8 miles round-trip (Arapaho, 2018). Tectonic processes and the climate are responsible for glaciations and would not form without both properties. The active movement characteristic of Andrews categorizes it as a glacier. The snow drifts into cirques from the strong winds blowing over the Continental Divide, giving the wind drift glaciers their name (Griffin, 2012, pp. 15-19).

Glaciers are essential to two basic Earth cycles. Both the rock cycle and hydrologic cycle are impacted by them. Water that falls in high altitudes or high elevations, the precipitation gathered does not always flow straight to the sea, this may become fragment of a glacier. Glaciers form from snow accumulation, compaction and recrystallization appears to be stationary, but glaciers move extremely slowly. The ice is stored for many years, sometimes thousands, but eventually it melts and makes its way to the sea. Valley (Alpine) Glaciers and Ice Sheets are the two types of glaciers (Lutgens, 2016, p. 396). All glaciers have a pile of rocks, sediment, and other debris called a moraine at their terminus. Increasing temperatures has caused mountain glaciers to melt faster, the Arapaho Glacier has receded drastically. Collections of data since 1960 indicate diminishing of at least 40 meters (Przyborski, 2005).

Courtesy of NASA, 2005

Arapaho Glacier is an alpine glacier that melts, contributing to the rise of the sea-level. The arrows in the photos reveal the changes in the surrounding topography from 1898 to 2003 (Przyborski, 2005).   

upper section of Arapaho Glacier from the summit of N. Arapaho Peak. (08/26/11), courtesy of summitpost.org

Photo of Arapaho Glacier and South Arapaho Peak by Jeremy Weiss, courtesy of getboulder.com, 2015 

This is what the glacier looked like in 2015. Once Boulder’s primary source of water, was diminished to a snowfield in 1968. It is still the largest glacial ice body in Colorado (Cook, 2016). Through the years there have been dramatic changes to the glacier and its surrounding features. More of the glassy bedrock shows as the glacier melts away, the craters that formed from erosion have become more distinct, and the once thriving watershed is no longer able to primarily support Boulder with water. I took particular interest in this glacier, because studying its changes and other glacial changes can help us predict future solutions in water supply.

References

Arapaho Glacier and South Arapaho Peak (2018). Retrieved from http://www.protrails.com/trail/454/indian-peaks-wilderness-area-arapaho-glacier-and-south-arapaho-peak

Cook, T. (2016). Boulder’s Disappearing Glaciers. Brock Media. Retrieved from http://getboulder.com/5113-2/

Lutgens, F. K, Tarbuck, E. J., & Tasa, D. (2016). Essentials of geology. (13th ed.). Upper Saddle River, NJ: Prentice Hall (Pearson). ISBN-10: 0134446623; ISBN-13: 9780134446622

Griffin, K. (2012). Geology teacher guide to Rocky Mountain National Park. Retrieved from https://www.nps.gov/romo/learn/education/upload/Teacher_Guide_to_RMNP_Geology.pdf

Hopkins, R.L. & Hopkins, L.B. (2000). Hiking Colorado’s Geology. Seattle, WA: The Mountaineers. IBSN: 0-89886-708-8

Myrone (2011). Arapaho Glacier. Retrieved from https://www.summitpost.org/arapaho-glacier/750299

Przyborski, P. (2005). Glaciers, Climate Change, and Sea-Level Rise. NASA. Retrieved from https://earthobservatory.nasa.gov/images/5668/glaciers-climate-change-and-sea-level-rise