Nature's Circus Elephants Earthcache
In Missouri, United States
Size:  (not chosen)
How Geocaching Works
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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.
(No hints available.)
Last Updated: on 7/22/2015 9:35:21 AM Pacific Daylight Time (4:35 PM GMT)
Coordinates are in the WGS84 datum