Rock House of Grayson Highlands EarthCache
Rock House of Grayson Highlands
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The Grayson Highlands Park is on U.S. 58 midway between
Independence and Damascus. The Park entrance is 8 miles west of
route 16 on US 58. Just follow your GPS since this EC is easily
spotted from the road!. Parking is very nearby.
The 4,935-acre Grayson Highlands State Park showcases the
Natural beauty of waterfalls, red spruce-fir forests and igneous
rock outcroppings such as the Buzzard's Rock , Listening Rock and
the Big and Little Pinnacles as well as the Rock House
Native trout streams, rugged mountains, and high alpine meadows
with panoramic vistas of valleys below are features of the Park. A
community of hardy wildflowers, shrubs, insects, birds, amphibians,
and mammals that can withstand the harsh conditions of the open
highlands have adapted to life in the alpine meadows.
The Rock House
Most people do not know that the Mount Rogers chain with
the Surrounding mountain peaks are remnants of ancient volcanoes.
Roughly 750 million years ago, rift-related (divergent) volcanoes
erupted along part of the axis of what was to become the
Appalachian Mountains. The major peaks of the Mountain Rogers Chain
are: Mount Rogers, Pine Mountain, Whitetop Mountain and the Haw
Orchard Mountain with it’s Twin Pinnacles. Mount Rogers is
the highest peak in Virginia at an elevation of 5729 feet. The
Mount Rogers chain occupies about 206 square miles. This Earthcache
is but one of several wonderful outcrops of the Mount Rogers
chain.
Because of the volcanic activities of the Mount Rogers
Chain, its geological history is very different from most of the
Appalachian Mountains. Peaks and outcroppings on most ridges of the
“Appy” mountains are definitely sedimentary rock. The
sedimentary rock is predominately limestone with sandstone/shale
found in the more northern areas. The volcanic eruptions here have
left major igneous Formations. These formations have been weathered
by millions of years of wind and rain.
Beside its beauty, one of the most interesting geological
facts of the Rock House is the nature of the Rock
itself. While most outcrops in the Park are igneous and are
composed mostly of rhyolite the Rock House is a
conglomerate! As we stated earlier, the more Northern regions of
the Appalachian Mountain chain are all sedimentary rock, but within
the Park, most rock is igneous due to the ancient volcanic
activity. Most agree that the base rock here is diamictite with
many different cobbles and/or drop stones of varying composition
found ‘suspended’ within the diamictite. You can easily
observe large quartz, rhyolite and cranberry gneiss cobbles within
the Rock House. Be sure to carefully examine the Rock
because you will be required to identify and photograph one of the
cobbles.
Drop Stones
More Drop Stones
And Still More Drop Stones
How was the Rock House formed? There are differing
opinions but there is one thing is for sure, there had to be water
and/or ice involved in the process. The drop stones or cobbles had
to be transported and deposited within layer after layer of mud,
which with enormous pressure and lots of time became the base rock,
diamictite. All conglomerates are composed of at least two
different rocks. One is the base rock such as sandstone and the
other are the particular cobbles of another entirely different rock
such as quartz pebbles. Instead of the more common sandstone being
the base rock, this conglomerate it is diamictite and the cobbles
are metamorphic (cranberry gneiss), igneous (rhyolite) and quartz
rocks.
Now for the fun part of your visit. In order for you to
claim a find of the Rock House you must complete the
following tasks and email the answers to numbers 1. and 2.
1. Estimate to within 10 feet, the height and width of the
Rock House, 2.While standing at the base of the
Rock, what is the elevation?, 3. Find and photograph
an example of one of the drop stones within the Rock. Point
to the stone with your GPSr. You may use the above pictures as
guides to finding the cobbles. Lastly, 4. as an option, post
a photo of yourself holding a GPSr with the Rock House in
the background. Have fun and enjoy another one of Mother
Nature’s creations. There are several other EarthCaches to be
discovered at the Grayson Highlands Park. Go for them!
This Earthcache was approved by the
Geological Society of America
| We have earned GSA's highest level: |
 |
Additional Hints
(Decrypt)
Gurer jvyy or n "ebpxva' tbbq gvzr va gur byq ubhfr gbavtug!"
Treasures
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