Small Caves-“Behind the Falls”
Behind Oak Hill Falls at Grahn, Ky. There are two small
openings, each shaped like a convex lens (magnifying glass) if
viewed from the side. The floor is relatively smooth and free of
debris such as loose rocks (at the time we visited) and dirt but
ceilings are a different story as they appear to have many loose
rock ready to fall. Do not enter the caves themselves as this
would be dangerous.
Photo by Ammosuperman
The Surrounding Rock
The rock that is seen at this location is sedimentary. It has
been eroded away from rocks millions of years ago and turned into
sediments. These tiny sand-grain sized or smaller particles were
washed into the shallow waters of ancient seas and settled to the
bottom. Over vast amounts of time these layers of sediments were
compacted and cemented together to form the rock we see today. As
the land raised (see below for more information on this event) due
to the collision of two crustal plates, the shallow seas receded
and the process of erosion started all over again.
Formation of Caves in Kentucky
Caves form as water seeps into the ground and enters into cracks
in the rock, Water, being slightly acidic dissolves the rock
creating larger cracks and flows in small streams underground. Over
time the small stream wears away at the surrounding rock and
attacks the rock on two fronts: first by acidic propertied the
dissolving of the rock and secondly by eroding the materials as
surface water wears away giant boulders. As time passes the flowing
water will eventually cut downward into the rock layers leaving
open space at the top where water seeping in can deposit dissolved
materials and begin forming stalactites and other cave features
such as ribbons, soda straws, etc. Kentucky has vast amounts of
limestone, which is particularly susceptible to dissolution by
water. This forms the sinkholes and caves that are so prevalent,
especially in the Bluegrass Region.
Diagram from
www.esi.utexas.edu/outreach/caves/caves.php
Kentucky is noted for many things and has one of the largest
cave systems in the world, Mammoth Cave in the west-central part of
the state. But here in Carter County there are extensive cave
systems as well. Carter Caves State Resort Park, only a few miles
from this location is an area well-known for its caves and the
biodiversity within them.
Photo by Ammosuperman
The small cave entrance can be seen near the center of the
above photograph. Note the shape of the opening.
At this location, these caves are relatively young. The floor
has been worn smooth and water does not flow continually through
them. It appears this is an event that happens after a hard rain as
the rock debris is piled up at the entrance, leading one to believe
that rushing water cleans the cave as it exits.
Qualifications for credit:
To get credit for the EarthCache, email the answers to the
following questions and then post a picture of you holding your
GPSr with the small cave in the background (this is the one to the
left and can be taken from the road if necessary) 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 in the water or the batteries died, let us know first
and we will work something out.
Questions:
1. What is the estimated overall height of the small cave?
2.Why does water dissolve limestone?
3. What is the texture of the rocks that make up the pile in
front of the smaller cave? Rough, smooth, glassy, etc.
Credits and Ammosuperman EarthCaches:
Special thanks to Fred, Carolyn, and Harold Collins (I) for
showing us this area and for their insight and history of the Grahn
region.
Special thanks to Mr. Greg Shuck from the Louisville
Firebrick Co. who owns the land and has given permission for
EarthCachers to visit this unique site.
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.
