GC1W0AN Andrews Tarn
Type: Earth | Size: Other | Difficulty: | Terrain:
By: Me & Bucky @ | Hide Date: 07/16/2009 | Status: Available
Country: United States | State: Colorado
Coordinates: N40° 17.316 W105° 40.702 | Last updated: 08/30/2019 | Fav points: 0

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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 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 at the Glacier Gorge Trailhead and the hike is up a well-marked trail. The trailhead parking area is often filled in the summer months, and shuttle bus transportation is available at the Bear Lake shuttle bus parking area. Prepare for a strenuous hike. Your one-way journey will be about 5.2 miles with an elevational change of 2,200’. The starting elevation is approximately 9250’, so bring sunscreen for the bright sun and extra water for the dry air. Afternoon thunderstorms are always possible in the summer months so plan accordingly.

The given coordinates will lead you to the eastern end of Andrews Tarn, the lake formed by Andrews Glacier. A tarn is a lake that occupies the erosional basin of a cirque. In the case of Andrews Glacier, the present form of the cirque was carved out during the Pinedale Glaciation, which occurred from about 10,000 to 30,000 years ago. The primary period of Pinedale Glaciation within the Park lasted from about 18,000 to 20,000 years ago.

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, these cirques were again occupied, but with much smaller glaciers.

The rock on which you are standing is a recessional moraine formed at the mouth of the cirque. The moraine has formed a dam across the opening of the cirque, which keeps up the level of the tarn. Stream erosion has begun to cut through the moraine on the north side, and you can see the makeup of the moraine by looking at the glacial till within the cut.


To log this EarthCache, complete the following:

1.) Estimate (or measure with your GPS receiver) the east/west length of Andrews Tarn.

2.) Measure with your GPS receiver the length (east/west) and width (north/south) of the moraine which is acting to dam Andrews Tarn.


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.

Hopkins, R.L., and Hopkins, L.B. 2004. Hiking Colorado’s Geology. Seattle, Washington: The Mountaineers. 240 p.

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


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!

09/18/2018 By magashi
answers have been sent! so i did the easy part of the hike first, to sky pond - well easy aside from that scramble up the falls!! it was insanely windy but the weather was perfect for a quick (ha!) scramble up the rocks and boulders to the tarn & glacier. there were a few parts where the trail seemed to disappear, luckily i had the gps track for it downloaded so i just followed that.

08/01/2018 By PackSux
Wow! Came over for the two earthcaches after a hike to Sky Pond (maybe should've just done one or the other today!) But, the weather was perfect for hiking, so I didn't mind too much. This was an awesome place to visit, thanks for bringing me up here! Answers sent. TFTC!

08/17/2017 By Mrs Scothog
We had a fabulous walk up here with Dan from Kirk's Mountain's Adventures - see my log for the the glacier earthcache. The tarn was really beautiful, with echoing cliffs on one side and an infinity pool effect - it looked as though the pool just ended into thin air at the end because the ground dropped off so steeply after the moraine lip.

Thank you for encouraging us to come up here - these two earthcaches really made our stay in the RMNP!

FP awarded, TFTEC and greetings from Scotland!

09/09/2015 By The Speis
6th of 7 on the day w/ Tubymundo. Thanks for placing these two caches which inspired us to make this hike. The hike to Andrews Glacier was amazing, beautiful, demanding & very rewarding. On the way up we lost the trail when it crossed the creek & ended up bouldering our way for a while until we relocated the trail. The final climb up the moraine was rough but the Earthcaches and some encouragement from a pair of hikers on our way down carried us through. Once we made the crest we understood, "is it windy during your visit? likely it is!" and laughed at that a lot. We each took a celebratory drink of pure glacier water just as it left the tarn to tumble down the valley (look mom no filter) & it was the coldest purest water I've ever tasted. TFTC

07/26/2015 By icezebra11
Today I made the wonderful hike into Glacier Gorge and to Andrews Glacier. When I arrived at 7:45 am at the Glacier Gorge parking area, all the spots had already been taken but the ranger said spots were still open at Bear Lake so I ended up parking there. The weather was absolutely gorgeous! I was enjoying myself so much I missed the turn to head up Andrews Creek and ended up at Timberline Falls before I realized what I'd done. That sure added to the elevation gain unnecessarily! So I backtracked down the trail and found the trail I needed to take. After a short ways I got to the end of the trees and came upon the sign for the restoration. Just after that is where I strayed off course again and ended up too high and traversing across the boulders and talus. I apparently did what EstesLynne said some other hikers had done when she was here. Eventually I made it back onto the trail and slowly made my way up the steep moraine. Once I reached the crest of the moraine, the tarn and the glacier were quite breathtaking!

I used my GPS to obtain the necessary measurements of the moraine and then headed for the glacier and got the length of the tarn. At the glacier I marked the point for the Andrews Glacier cache. Answers emailed.

While waiting for my waypoint averaging to complete, I heard voices up high. Looking up I saw three people on the glacier and they glissaded down to the tarn. It was pretty cool. Then I headed down the gorge and eventually to the parking area.

Thanks Me and Bucky for these wonderful earthcaches, without them I don't know if I'd ever had made it to this beautiful spot!!!

This entry was edited by icezebra11 on Monday, 27 July 2015 at 01:19:55 UTC.

10/08/2014 By sciguy2
A group from the Anthem Ranch Hiking Club hiked up to The Loch and a few of us decided to visit Andrews Glacier as well so I took the opportunity to pick up two more of your wonderful Earth Caches. It was a beautiful day though we did have a bit of snow to clamber through as we scaled the moraine.
Answers to #1 and #2 will be in an email soon. Photo is attached

TFTC!