Travel out to this site is over a minimum of 15 miles of dirt road. Some is graded, but the last 3 miles or so are over a 2-track road through the bottom of the valley. Parking is at N 41 57.710 W 109 11.765. The Boars Tusk is located in the Leucite Hills Volcanic Field north of Rock Springs. It is a volcanic neck which rises several hundred feet above the Killpecker Valley floor. It is one of the Leucite Hills lamproites, and is composed chiefly of agglomerate and tuff. The volcanic neck consists of two spires. The southern spire has an outer zone of dense, non-vesicular lava with abundant native rock xenoliths. Xenoliths (from xeno meaning “foreign”, and lith meaning “rock”) are pieces of native rock that were picked up by the magma when it passed through the native rock layers to the surface. Pieces of this rock broke off into the magma, and while most melted, some remained to be encased in the magma when it cooled. After erosion, these are now visible in the exposed lava. Most of the xenoliths present in the Boars Tusk are composed of shale, siltstone, and breccia from the Green River and Wasatch Formations. In addition to the sedimentary xenoliths, some granitic xenoliths are also present. The coordinates will take you to a large boulder on the southeast side of the Boars Tusk. This boulder has numerous visible xenoliths. To receive credit for this Earthcache: 1.) Count the xenoliths which are greater than 3” in diameter that you can see on the south face of the large boulder at the site of the coordinates. What color are most of the xenoliths you can see? After you have emailed me the answers to these questions, post at least 1 picture of you with your GPS receiver with the Boars Tusk in the background from this site. The above information was compiled from the following sources: Hausel, W.D. 2006. Geology and Geochemistry of the Leucite Hills Volcanic Field. Wyoming State Geological Survey Report of Investigations No. 56. Mirnejad, H. and K. Bell. 2006. Origin and Source Evolution of the Leucite Hills Lamproites: Evidence from Sr-Nd-Pb-O Isotopic Compositions. Journal of Petrology 2006 47(12): 2463-2489. Published online on September 20, 2006. http://petrology.oxfordjournals.org/cgi/content/full/47/12/2463 Wikipedia: http://en.wikipedia.org/wiki/Xenolith |
Additional Hints (There are no hints for this cache)
11/25/2008 by tronaminer
A great day to go to this cache site. I was in my shirt sleeves. I came in from the East and left going to the South. Trick routes to find to the Tusk. It appears that people are chipping away at the xenoliths at the cache site. Also writing on the rocks. Anyway always glad to get an excuse to come up here. Thanks.
9/22/2008 by pepsiman.
climbed to the top of Pilot Butte, wasnt about to climb to the top of this one. It was too scary. What a pretty spot.
8/6/2008 by jeewy
We had A little accident with Princess Alex here, but were definitely there. Princess know about volcanic rocks now. Found with Boomerangs too. TFTC
8/6/2008 by Boomerangs
Found it, but had a small accident when one of the mt. goats fell and scraped herself up.
6/11/2008 by jevans7
Out on a cold and windy day First time that I have stoped here have seen form far off came for the cache and git a ftf out of it putting two pic. me at boars tusk and me at rock not south side thanks for hid
Additional Hints (There are no hints for this cache)