High Ground Quartz Pebbles
This site, along with many other locations along the trails at
the Berea Pinnacles contains these mysterious quartz pebbles. They
are generally the same size, an inch or less and have smooth edges
unless fractured or broken.
When I was younger my grandfather and I would often be in the
woods near cliffs or creeks and see these type of rocks. I remember
he called them Jack Gravels. So this ones for you Papaw.
The shape of the pebbles tells us that they were eroded from
larger rocks and have been worn smooth by water. As these rock were
in an ancient stream or river bed, flowing water, moving sand and
other sediments over the heavier pebbles has removed the sharp
edges and left them as we see them today. During times of flooding,
the faster moving water would have moved these quartz rocks
downstream and ground them against heavier, non-moving rocks
further eroding away the pebbles and in turn, eroding away the
larger rock as well.
The sand surrounding these pebbles was cemented together to form
the sedimentary rock outcrops so prevalent at these pinnacles. As
time and erosion changes the landscape, so it has with the outcrop.
The sandstone has been worn away leaving the harder quartz pebbles
exposed in places and completely free from the surrounding rock in
others. These pebbles that have been freed from the surrounding
sedimentary rock are once again subject to being carried down
stream or down the hill by water. These pebbles from here can be
found many miles down stream in creek beds or river bottoms.
It has been suggested that the quartz itself was transported to
this area by ancient rivers that flowed from what is now Canada
into Kentucky. According to researchers Stephen Greb from the
Kentucky Geological Survey, and Allen Archer from Kansas State
University, the river drained nearly as much land in North America
as the Amazon does today in South America. The river that was
responsible for this transport of materials is of course no longer
in existence.
The Pinnacles in Madison County are some of the highest
elevations for miles around. It is hard to imagine this region as
being under water. We often judge change as we see it. Geologically
speaking this area has not undergone major changes for many, many
thousands of years. In the time of Daniel Boone or Lewis and
Clarke, or the original settlers and explorers of this region, the
American Indians, would have looked at this area, the watershed and
the rocks, and most would have been the same then as it is today.
Trails may have changed and looking out from this location we see
the houses and roads humans have built, but the geology changes so
much more slowly.
Qualifications for credit:
To get credit for this EarthCache, email the answers to the
following questions and then post a picture of you and your GPSr
with the pebbles (like the photo above) in the picture when you log
your find. Posts with no pictures or without emailing the answers
will be deleted. If no picture is possible, for instance you
dropped your camera over the edge or the batteries died, let us
know first and we will work something out.
Questions:
1. What is the elevation at this site?
2. What process is responsible for giving these pebbles their
rounded shape?
3. What type of rock is predominant at this site, igneous,
metamorphic, or sedimentary?
Credits and Ammosuperman EarthCaches:
This EarthCache was created by a team of two Platinum EarthCache
Masters, Ammosuperman EarthCaches are a collaborative effort. We
have used resources such as the Internet and magazine articles as
well as personal experience in visiting the sites, as research
tools in its construction. Our goal is to learn more about our
planet and to pass along what we have learned to others having
similar interests. We hope you enjoy the experience.
Special thanks to Jay Buckner and Berea College for allowing
this EarthCache at this location, and to Cav Scout who has another
EC nearby.
Special note: Tillie the Trail Dog may want to hike up the trail
with you. If you are lucky enough to have her join you (she lives
nearby) please share a little water and maybe a snack with her. She
is an excellent guide, just don't get close to the edge like she
does. We think she may have been a Sherpa in another
life.