Roaring River Spring, Missouri
November 06, 2012
Photographer: Tommy Hornbeck
Summary Author: Tommy Hornbeck 
Roaring River Spring in southwestern Missouri emerges from the base of a limestone cliff with an average daily flow of 26 million gallons (98 million liters). A smaller spring at the top of the cliff creates the waterfall you see splashing in the main pool. The pool is only about 10 ft (3 m) across but if you were to dive in (not recommended), you'd find yourself in a large cavern that's recently been explored down to a depth of 223 ft (68 m). This cavern follows a displaced fault line hollowed out by the action of moving groundwater.
With more than 3,000 known springs, the state of Missouri has large areas of karst topography where the movement of groundwater has led to the formation of losing streams, caves, springs and sinkholes. The bedrock of these areas is predominantly dolomite and limestone. Rainwater mixes with carbon dioxide and forms a weak carbonic acid that creeps through cracks and fractures in the bedrock gradually carving out underground rivers that on occasion can rise to the surface forming the springs.
One way to find the source of a spring's water is dye testing. In this case, fluorescent dye was injected into a sinkhole on the prairie a few miles south of Cassville, Missouri. Later, the dye reappeared at Roaring River Spring, having moved some 6 mi (10 km) horizontally and 395 ft (120 m) downward, to the surface of the Roaring River Spring, in eight days. The spring water flows into one of the oldest fish hatcheries in the state. This hatchery produces and stocks more than 250,000 rainbow trout (seen swimming above) each year into local streams, most of the fish going into the Roaring River itself. Photo taken on October 24, 2012.
Photo Details: Nikon D-80 camera; 1/30 sec. exposure; f/3.5; ISO 1600; 16 mm lens.
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