GC230C5 Earthcache Mills Lake Erratic
Type: Earth | Size: Other Other | Difficulty: 4.5 out of 5 | Terrain: 3.5 out of 5
By: Me & Bucky @ | Hide Date: 01/15/2010 | Status: Available
Country: United States | State: Colorado
Coordinates: N40° 17.487 W105° 38.567 | Last updated: 08/30/2019 | Fav points: 0

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 Glacier Gorge Trailhead, or you can park at one of the several shuttle bus parking lots and take the shuttle to the trailhead.

The given coordinates will lead you to a glacial erratic on the shore of Mills Lake. A glacial erratic is a boulder that has been transported from its place of origin by the movement of ice. When the glacier melted or retreated, the erratic was left behind.

The erratic at this site is nearly spherical, and formed of pink granite from the Longs Peak-St. Vrain Batholith. This puts the age of the granite on the order of 1.4 billion years old.

Using a ruler or tape measure, find the diameter of this erratic. Assuming that this material has a density of 2.75 grams per cubic centimeter (gm/cm3), how much does this erratic weigh?


1.) To receive credit for this EarthCache, send me an email with measurements that you took for this erratic, along with its weight.

2.) Is this erratic made of similar material or different material than the rock of the lakeshore upon which it sits? Explain similarities or differences in your email to me.

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: 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!
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 Logs

6 Logs: Found it 6  

Found it 10/03/2018 By deniseflygirl
Yay! I enjoyed my day hike to Mills Lake & beyond. Omw back to the trailhead, I saw a moose. Answers sent. TFTEC! :-)

Found it 08/11/2018 By YamaGypsy
First time visiting this area of the park. Lemonheadmafia and I enjoyed the hike. Beautiful lake and scenery. He usually carries a fishing pole with him but forgot it at home this time. Definitely will need to make another trip here just to fish! Found the erratic and spent some time trying to figure out the equation. Answers sent. Thanks!

Found it 07/02/2018 By BarelyPolar
Very enjoyable hike with awesome scenery.

Found it 06/25/2018 By Pixel Magic
TFTC
Found during my training hike.
More Info to follow.

Found it 06/21/2018 By bengcopsa
TFTC

Found it 11/08/2017 By gpsbarb
Enjoyed skiing Trail Ridge Road yesterday in the clouds and truly loved hiking in the brilliant sunshine to Mills Lake today. Microspikes were handy to maintain grip in some slippery spots. I am from Cooperstown, NY and here visiting my college roommate and friend from 40+ years ago. I love these mountains. Great hike, beautiful views.......really appreciated the vastness of the mountains and the peace and quiet at the lake. Figuring out the answers to these questions made me recall math from 50 years ago....hopefully I came close with the answers. The hike was a wonderful challenge and I actually thought the math was a fun challenge too. Thanks for the lesson and the cache. This one gets a favorite point from us for the beautiful hike and the challenging earthcache. It was fun measuring a round object with a straight pole, struggling in the deep snow and sinking in the soft ice and falling and wondering where the bottom be would be and..................... but I think it all worked.