Friction Slab of the Red River EarthCache
Friction Slab of the Red River
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Difficulty:
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Terrain:
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Size: 
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The cache is a short drive from the Natural Bridge State
Park on Highway 11. This EarthCache can be found and easily seen
from the public right-of-way off of KY 11.
The Rock!
The Friction Slab can be found resting beside the
Middle Fork of the Red River. The Rock is a popular spot for
rock climbers. Just where did it come from? No one really knows,
but the most likely answer is due to erosion, it fell from the
nearby high ridge above the Rock. Due to further erosion, traces of
exactly where it fell from are impossible to determine. The boulder
is quite large which you will need to estimate its size. While you
may, climbing on the Rock is not a necessary requirement of
this cache. Any climbing is at your own
risk!
Up Close and Personal with the
Rock
Most of the defining geologic features of the Red River
Gorge were formed over 300 million years ago. Sediment, sand and
pebbles eroded from the early Appalachian Mountains were carried by
a large river and deposited as a delta at the edge of a shallow
inland sea that covered much of the middle part of North America at
that time. Over millions of years, the Appalachian Mountains were
worn down, the sediments turned to rock and the inland sea receded.
Rivers cut down through the flat layers of sedimentary rock.
Because sandstone is a harder rock, it resisted erosion better than
the shale and siltstone layers above and below. Erosion and
weathering over millions of years sculpted the striking sandstone
cliffs and intriguing geologic features that we see today in the
Red River Gorge. The Friction Slab is just one of these
wonderful geologic features.
The deeply dissected landscape is an intricate maze of
narrow, winding ridges and valleys separated by steep slopes and
continuous bands of high sandstone cliffs, making travel between
the uplands and valleys very difficult. As one hikes through the
Red River Gorge Area you cannot help but wonder how the early
settlers manages to traverse the area. Yes, it was easy to go
around the Friction Slab but other areas present a far more
and seemingly impossible trek!
Erosion and weathering over millions of years sculpted the
striking sandstone cliffs and intriguing geologic features that
this sandstone came from now resting in the Red River. The deeply
dissected landscape is an intricate maze of narrow, winding ridges
and valleys separated by steep slopes and continuous bands of high
sandstone cliffs, is where most of the large sandstone boulders you
see in the river came from. Most of the large River boulders such
as the Friction Slab fell thousands if not millions of years
ago from the surrounding cliffs.
The Friction Slab rock and others in the area are from the
Mississippian, Pennsylvanian, and Quaternary Ages. The
Mississippian rocks, sandstone and siltstone's, as stated earlier,
were deposited by large rivers that formed a huge delta in this
area. Limestone, which is far more rare than the prevalent
sandstone, from this region was deposited around 350 million years
ago. Most all of the rocks found here are sedimentary and here is a
brief review of the types of sedimentary rock:
The primary types of sedimentary
rock
1. Sandstone- made up of sand grains cemented
together.
2. Shale- made up of clay particles smaller than
sand which makes it smoother
3. Conglomerate- made up of usually quartz pebbles
cemented together
4. Limestone- made of calcium carbonate often
deposited by sea life
5. Dolomite- like limestone but with more magnesium
in it
6. Coal- composed by the remains of plants and
animals
Note: in order for you to claim a find on this
EarthCache you must complete the following:
1. Post a photo of you and your GPSr with the Friction
Slab in the background. 2. Email us answers to the following
questions: A. After carefully examining the Rock beside
sandstone, what other sedimentary rock is found. Consult the above
list for the answer. B. Estimate the height of the Friction
Slab. C. Estimate the width (as viewed from the road) of the
Rock. Please, email only and do not post the answers on the
cache page.
This Earthcache was approved by the
Geological Society of America
| We have earned GSA's highest level: |
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Additional Hints
(Decrypt)
Unir n ebpxva' tbbq gvzr!
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