This earthcache is at the site of an old abandoned coal mine in
Turkey Run State Park near Sugar Creek.
This mine was in operation from the late 1800's through the
1920's. The coal was hauled out by donkey to heat the Lusk Home on
property and other buildings within the park. The mine was too
small to be of commercial value but was very valuable to the park
and to the only private owners of the park land; Salmon and John
Lusk. The coal here was formed during the Pennsylvanian Period when
Indiana was warm and swampy. The Pennsylvanian Period lasted from
320 to 286 million years ago. During the Pennsylvanian Period,
widespread swamps laid down the thick beds of dead plant material
that today constitute most of the world's coal. The term
Pennsylvanian is a U.S. coinage based on the frequency of rocks of
this period in the state of Pennsylvania; internationally, the
terms late Carboniferous Period or Silesian Period are
preferred.
Although most artist's conceptions of the Pennsylvanian Period
emphasize its prolific swamps, these were characteristic only of
the equatorial regions. The Southern Hemisphere, which was
dominated by the huge continent Gondwana, underwent a series of ice
ages during this period. These ice ages sequestered water in times
of ice growth and released it in times of melting, causing the
ocean to cyclically regress (uncover coastal lands) and transgress
(cover coastal lands) around the world. Repeating sequences of
sedimentary rock layers record these changes in sea level. From the
bottom up, a typical sequence is sandstone, shale, coal, limestone,
and sandstone again. Each such unit is termed a cyclothem and was
formed as follows:
(1) As ice melted in Gondwana, seas rose globally. Rivers and
streams deposited sand and gravel in the coastal lowlands as they
sought new equilibrium profiles (i.e., stable altitude vs. distance
cross-sections). This sand layer eventually became sandstone.
Although the coastal zones where sandstone deposition was taking
place at any one time were narrow, larges areas were blanketed by
these sediments as the seas rose and coastlines swept slowly
inland.
(2) As the rising sea neared a given location, a lush coastal
swamp developed. This deposited a thick layer of dead leaves, tree
trunks, and other organic material rich in carbon that would
eventually form coal.
(3) When the sea finally submerged the swamp, a shallow marine
environment appeared. The remains of shelly marine animals built up
on the sea floor and eventually became limestone.
(4) Ice began to build again in Gondwana, and sea levels began
to drop in a new phase of regression.
(5) Erosion of re-exposed coastal lands scraped off the topmost
sediments left by the last transgression, including some of the
limestone layer.
(6) Ice began to melt again in Gondwana, triggering a fresh
cycle of transgression. As many as 90 cyclothems have been found in
one place, one on top of the other. Each such cylothem records a
complete climatic cycle like the one described above. The first
reptiles evolved during the Pennsylvanian Period. These were small
(about a foot long) and outnumbered by the amphibians, which were
prosperous, diverse, and achieved lengths of up to 15 ft (4.6 m).
Insects also thrived; dragonflies with 2.5-ft (0.76 m) wingspans
were common. Over 1,000 species of Pennsylvanian cockroach have
been identified, giving this period the alternative, informal title
of the "age of cockroaches."
During this period, the decay of the many layers of plants
gradually got squeezed by heat and pressure to form the coal in
this part of Indiana. In 2000, the coal mine was blocked off to
protect humans and the current occupants.
To log this earthcache, you must do the following:
-Take a picture of yourself and GPSr in front of the coal mine
and post it at the time you log the cache.
-Email me with the answers to the following questions, which can
be answered from the signs at the coal mine. Do not include the
answers or pictures of the signs in your log. Failure to complete
any question of picture will result in log deletion.
1. What organic material formed the coal in this mine?
2. How thick was the material needed to form the coal seam and how
how thick is the seam?
3. Name one fossil on this sign.
4. Who are the current occupants of the coal mine?
5. Where was Indiana located during the Pennsylvanian Period?