GC1F803 Xenoliths of Greyrock Mountain
Type: Earth | Size: Other | Difficulty: | Terrain:
By: Me & Bucky @ | Hide Date: 08/14/2008 | Status: Available
Country: United States | State: Colorado
Coordinates: N40° 43.014 W105° 17.349 | Last updated: 08/30/2019 | Fav points: 0

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In the wall of pink Silver Plume Granite at this site are some dark colored chunks of rock. These are xenoliths of metamorphic parent material which were incorporated into the magma during the intrusion of the Log Cabin Batholith, about 1.4 billion years ago.

Xenoliths (from xeno meaning “foreign”, and lith meaning “rock”) are pieces of native rock that were picked up by the magma as it passed upward through the native metamorphic rock layers. Pieces of this rock broke off and became incorporated into the granite. After erosion of the parent material and uplift of the batholith, these are now visible in the exposed granite.

To log this cache, complete the following: 1.) Send me the coordinates and size of another xenolith which you have found along the trail. Include in your email the reason you feel this is a xenolith.


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:

2007. Chronic H., and F. Williams. Roadside Geology of Colorado, 2nd Ed.

2004. Hopkins, R.L., and L.B. Hopkins. Hiking Colorado’s Geology


Thanks to the Roosevelt National Forest for allowing placement of this EarthCache!

05/27/2018 By kauf
#956
Found during a vacation to the FoCo area - in addition to geocaching, Boyfriend and I hiked Greyrock Mountain! Hiking at elevation was tough, and I had a scare on our way back down, as I almost stepped on a rattlesnake! Good thing there was a bit of an adrenaline rush, and luckily the snake was pointed the other way... allowed me to be able to scurry down the trail. After making our way back down the mountain, I bought myself a beer. Here’s to being able to cache another day! TFTC!

03/31/2018 By Barasaur
Went for a hike with Pixel Magic and Waawhoo around Gray Rock. Had a great day hiking with slightly cloudy skies and around 50 degrees. We covered around 10 miles in our cache hunting with over 3000 feet elevation gain throughout our hike. Thanks for the fun day walking around in the mountains.

Waawhoo will send our answers to the EC.

(9894)

03/30/2018 By waawhoo
Hiking up here with barasaur and Pixel Magic, we stopped here to look at the example of the Xenolith. Email sent thanks for the earth cache!

03/26/2018 By Desert Rogue
Tftc, I enjoyed your Earthcache series here! I found quite a few xenoliths, including (maybe...) this crazy looking one! Do you think it is one?? Seems to have feldspars in it....

07/04/2016 By Phred312
I came to Colorado for GW14. I wanted to find an earthcache that started with the letter "X". I am working on a challenge cache in Kentucky that requires finding earthcaches with names that start with each letter of the alphabet. The trip to Greyrock Mountain was certainly the best part of my entire trip. It was awesome. Took pictures. Left happy. Thank you. Find 4315