Nature's Circus Elephants Earthcache EarthCache
Nature's Circus Elephants Earthcache
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The area is in the St. Francois Mountains Section of the Ozark
Natural Division. It is encircled by a braille trail designed
especially for access by the visually and physically disabled.
Ascending the overlook steps is not necessary to log this cache.
One of the most curious geologic formations in Missouri is found at
Elephant Rocks State Park. Giant boulders of 1.5 billion-year-old
granite stand end-to-end like a train of circus elephants. Many of
the elephant rocks lie within the seven-acre Elephant Rocks Natural
Area. This natural area is owned by the Department of Natural
Resources and is recognized for its outstanding geologic value.
This extraordinary herd of pink elephants began during the
Precambrian era. Granites form when felsic magma (molten rock below
the surface) intrudes into the subsurface and cools slowly, forming
dark pink rock bodies with a course grained texture deep in the
earth. A close look at the skin of these giants reveals coarse
grains of quartz. The stone is chiefly orthoclase, a pinkish
mineral with bright, glassy cleavage faces. Other iron-rich
minerals are also present and help give the elephants their color.
It is today called Graniteville Granite (named for the town about a
kilometer south of the park). Chemically, granites are similar to
rhyolites but differ in the fact that their grain size is much
larger. As the weight of the overlying rock was removed by erosion,
horizontal and vertical cracks developed, fracturing the massive
granite into huge, angular blocks. Water permeated down through the
fractures, and groundwater rounded the edges and corners of the
blocks while still underground, forming giant rounded masses.
Erosion eventually removed the disintegrated material from along
the fractures, and exposed these boulders at the earth's surface.
Some rocks are about the size of an elephant while others are much
larger. The park trail takes the hiker through the elephant rocks.
The largest of the elephant rocks is hundreds of feet long and
serves as a platform offering excellent views of the surrounding
area. Other enormous rocks are ‘balanced’ on top. One section of
the elephant rocks resembles a rock maze with tight passages and
steep walls. You will notice that the maze tends to have many
parallel passages which were inherited from the original fracture
pattern.
Physical and chemical weathering in low areas on the crest of the
large granite outcrop has produced distinct, roughly circular
depressions up to several feet in diameter, called "solution pans"
or "tinajitas." The short-lived pools of water that collect in
these depressions often provide a home for tadpoles and grasses.
Since no official census of the herd has ever been taken, the exact
number of "elephants" inhabiting the park is unknown. Although the
elephant rocks are continually eroding away, new elephants are
constantly being exposed. Information collected on Dumbo, the
patriarch of Elephant Rocks State Park, shows that he is 27 feet
tall, 35 feet long and 17 feet wide. At a weight of 162 pounds per
cubic foot, Dumbo tips the scales at a hefty 680 tons. Just outside
the park is the oldest recorded commercial granite quarry in the
state. This quarry, opened in 1869, furnished facing stone for some
Eads Bridge piers across the Mississippi River, and from 1880 to
1900, millions of paving blocks for the St. Louis levee and
downtown streets came from this quarry. Other nearby quarries
supplied granite for many major St. Louis buildings, as well as
stone for the turned columns on the front porch of the Governor's
mansion in Jefferson City. Today, this granite is used primarily
for monuments and building veneer. The higher quality granite
blocks produced from quarries before the area became a state park
were used for building homes and other structures; the flawed and
damaged stone was hammered into blocks, which were used for paving
streets. Roughly the size of a shoebox, these granite paving blocks
sold for about eight cents each. At that rate, a good block maker,
producing 50 blocks per day, could earn a whopping $4 a day! Pretty
good wages for a very hard day's work.
Dumbo and her unique herd of pink granite elephants are the
reigning monarchs of Elephant Rocks State Park. To log this cache
you won’t have to take along bags of peanuts to make friends with
these magnificent giants, just your GPS unit and perhaps a camera.
At the trailhead is a small shelter which has much information on
the Elephant Rocks’ formation and local commercial quarries which
you will want to view.
To properly log this earthcache please respond to the following
questions:
1. What was determined to be the best use of the granite boulder
located at these coordinates N 37° 39.317’ W 090° 41.102’?
2. Cite the three reasons the red granite of Elephant Rocks was
popular with builders.
Additional Hints
(No hints available.)