When molten rock belched up from the Earth and oozed across its surface 1.5 billion years ago, no one was around to see it slowly form this majestic swimming hole, known as Rocky Falls.  That volcanic rock hardened into reddish-brown rhyolite porphyry.  The rushing spring-fed waters would have carved softer rocks into a canyon, but rhyolite is too hard to be eroded in that way.  Instead, the stream wriggled into little cracks, eroding any soft rock, and leaving smooth hard rhyolite ‘shut-ins.’  Shut-ins are common in the Ozarks and describe the unique plunge pools and chutes streams carved millions of years ago in the tough volcanic rock.

Rocky Falls is a unique shut-in in a state full of them. A dramatic 40-foot-tall waterfall pours into a large swimming pool.  Though the waterfall is most dramatic after rainfall, even when the waters run low, one can float around and enjoy this unique Missouri swimming hole.