The Man-made Natural Wonder
Approximately 150 miles southwest of Atlanta, in the
US state of Georgia, is a network of gorges and massive gullies lovingly called
Georgia's “Little Grand Canyon.” It is considered to be one of Georgia’s “Seven
Natural Wonders”, except it isn’t at all natural. These impressive canyons were
created not by the action of a river over millions of years but by rainwater
runoff from farm fields in less than a century.
Providence
Canyon began forming in the early 1800s because of poor farming practices that
prevailed across the nation and especially in the south. In those early days of
agriculture, land was cheap, unlimited and seemingly expendable giving way to a
combination of plantations, small farms, and eventually a sharecropper system
that not only degraded the land but also kept farmers in debt and uneducated.
Native forest cover were cleared so the land could be farmed, and no measures
were taken to avoid soil erosion leading to massive loss of topsoil. Small
gullies began to form and rapidly grew deeper and more extensive, until they
were three to five feet deep by the 1850s. These small channels began to
further concentrate runoff increasing the rate of erosion. Today, some of the
gullies at Providence Canyon are 150 feet deep.
Despite
its recent formation, Providence Canyon is a treasure trove for geologists and
visitors alike. Erosion has exposed the geologic record of several million
years within its walls, and minerals have stained the sediments, creating a
wide range of colors.
Providence
Canyon lies in a region that was formed by deposition of marine sediments
between 59 and 74 million years ago. The soil in the top part of the canyon
wall was deposited about 60-65 million years ago, just after the age of the
dinosaurs. Its fairly coarse sand is a reddish color caused by the presence of
iron oxide.
Underneath this formation lies what is known as the Providence
Sand, which makes up most of the canyon walls. It’s one hundred and nineteen
feet thick and was deposited about 70 million years ago. The upper part of this
layer is very fine sand mixed with a white clay. The middle layer is coarse and
more colorful, with beds of yellow (limonite) and purple (manganese) deposits.
The lowest and oldest layer is a black and yellow mica-rich clay. The bottom of
the canyon floor was deposited about 70-74 million years ago, and is orange in
color but is poorly exposed and overgrown by vegetation.
Providence
Canyon continues to erode, however, the floor of the canyon is more resistant
and growth of pine trees, buses and other vegetation has helped stabilize the
soil.
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