Caves of the Ledge
This is an EarthCache and
as such there is no container to find. An EarthCache is simply a
place to go and learn about the world we live in. You will be asked
to email me the answer to a few questions in order to log this as a
find. To log this cache you will need a GPS and a
flashlight.
Ledge Park, covers 83 acres along the Niagara Escarpment
providing excellent views of the Horicon Marsh and the surrounding
countryside. The Park has over 2 miles of well groomed hiking
trails ( http://www.dodgeparks.com/pdf/Map-Ledge.pdf ) which pass
through the bluffs, woods and prairie areas. The park is open from
8am to 8:30pm. Dogs must be leashed at all times. Park entry is
free.
For this EarthCache you will walk a trail through Niagara
Escarpment exposures. Be prepared: wear good hiking shoes and pack
typical supplies such as bug spray and a first aid kit. Due to the
steep nature of bluffs please take special care if you bring
children to the park. The Ledge Rocks trails and the Ledge Overlook
Trails do have 30-50 foot drop-offs and are NOT recommended for
small children. The Upper Woods and Lower Woods trails are much
more family friendly. At no time will you be required to leave the
trail.
A cave or cavern is a natural underground void large enough for
a human to enter or extending from the Earth’s surface far enough
to be in constant darkness. There are three basic ways in which
caves are formed: (1) caves formed by pressure or flow, (2) caves
carved by erosion, and (3) caves dissolved by solution. The caves
dissolved by solution (normally seen in limestone or Dolostone
formations) are the most common caves.
The National Speleological Society of America states that there
are more than 11,000 caves in the United States, and it appears
likely that 100,000 caves exist in the world. While this location
does have legitimate caves according to the definition above, it is
doubtful that these caves would be included among that worldwide
number.
Cave formation
You are standing on the Niagara Escarpment which is made of
limestone / Dolostone. It is very likely that the caves here were
formed at least in part by the second and third type of cave
formation above: “carved by erosion” and “dissolved by solution”.
The process of cave formation by solution begins when rainwater
absorbs carbon dioxide (CO2) as it falls through the atmosphere. As
the water absorbs carbon dioxide it becomes acidic. As the slightly
acidic rainwater comes through the soil it absorbs even more carbon
dioxide from dead plant life. The addition of the CO2 changes the
ground water into a weak form of carbonic acid (H2O + CO2 = H2CO3).
As the weak acid seeps into the ground it eventually contacts solid
rock. If the rock is limestone or dolomite caves can form as the
slightly acidic water chemically reacts to the limestone as it is
flows into the Earth. As the water continues to react chemically
with the limestone a larger and larger space will form.
Much of the escarpment is made of limestone also known as
calcium carbonate (CaCO3) which was laid down when an ancient sea
covered Wisconsin. The limestone here was laid down as a limy ooze
made up of shell and shell fragments consisting of corals,
brachiopods, crinoids and other types of early life. Many marine
organisms extract calcium carbonate from the seawater to make
shells or bones and when these organisms die their shells and bones
accumulate on the seafloor. Over millions of years these sediments
hardened into what we see today as the bluffs of the Ledge.
* To claim this
EarthCache *
E-Mail me the answers to
the following questions:
(DO NOT POST IN YOUR
LOG).
Park at N43 27.908 W88
35.079 (Ledge Rock hiking trail).
Hike to N43 27.937 W88 35.101.
Here you will find a small
cave at the base of the escarpment.
#1. E-mail me: How deep
is this cave.
2. E-mail me: What forms
of erosion do you think are at work at the cave?
#3. E-mail me: Do you
think the presence of grass and other plant life above the cave
affects the caves development? Why or why not?
References:
http://dwb4.unl.edu/Chem/CHEM869A/CHEM869ALinks/rville.k12.mo.us/Cave/caveForm1.html
http://en.wikipedia.org/wiki/Cave
http://www.icr.org/index.php?module=articles&action=view&ID=161