McCormick’s Creek State Park is an amazing park for geology and
history. Apart from being the first state park in Indiana (1916),
the upland areas of the park are home to numerous bowl-shaped
depressions called sinkholes. Some are small, some are large, and
some are in groups or in rows. A few contain springs and small
streams that sink into the ground. All these features were formed
by the underground movement of water, which slowly dissolves the
limestone bedrock and forms an underground network of passageways
to carry the water. Sinkholes, which are formed as the limestone is
slowly removed from beneath the soil, carry the runoff from rain
and snow underground.
As the underground streams seek lower and lower levels, some of the
passageways are left high and dry. Wolf Cave is an example of a
large dry passageway that has been opened to view by erosion.
Erosion also leaves small remnants of the passage as natural
bridges. Litten Natural Bridges are an example. Features formed by
subterranean drainage are known as karst features and are
widespread in part of southern Indiana where limestone is found.
Limestone, with its high calcium carbonate content, is easily
dissolved in the acids produced by organic materials. About 10% of
the earth's land (and 15% of the United States') surface consists
of soluble limestone, which can be easily dissolved by the weak
solution of carbonic acid found in underground water.
When limestone interacts with underground water, the water
dissolves the limestone to form karst topography - an amalgamation
of caves, underground channels, and a rough and bumpy ground
surface. Karst topography is named for the Kras plateau region of
eastern Italy and western Slovenia (Kras is Karst in German for
"barren land").
The underground water of karst topography carves our impressive
channels and caves that are susceptible to collapse from the
surface. When enough limestone is eroded from underground, a
sinkhole (also called a doline) may develop. Sinkholes are
depressions that form when a portion of the lithosphere below is
eroded away.
Karst topography topo map from Indiana
A sinkhole can even collapse through the roof of an underground
cavern and form what's known as a collapse sinkhole, which can
become a portal into a deep underground cavern. The twin bridges on
the other side of Wolf Cave is a good example of a collapsed
sinkhole.
While there are caverns located around the world, not all have
been explored. Many still elude spelunkers as there is no opening
to the cave from the earth's surface. The largest such caverns,
lies just south of the state line in Kentucky... Mammoth
Cave.
To log this earthcache:
1)Wolf Cave collapsed at Twin Bridges. Use your GPS to mark and
calculate the length of the current cave. .
2) Take a picture of your team (with GPS) at the cave.
Note: Due to the threat of white-nosed
syndrome in bats, Wolf Cave is closed to thru traffic. All
information needed is still available. Cachers need to hike around
to twin bridges to mark your two points to find the answer. DO NOT
ENTER THE CAVE!