Elephant Rocks

Elephant Rocks is an outcropping of Precambrian granite in the Saint Francois Mountains of Iron County, Missouri, named for a string of large granite boulders that resemble a train of pink circus elephants. The boulders are weathered Graniteville Granite, a medium to coarse-grained rock containing alkali feldspar, quartz and mafic minerals, from a pluton that formed about 1.4 billion years ago during the Proterozoic era as magma cooled after intruding into volcanic rock and surrounding strata. Nearly vertical fractures developed as the granite cooled and were later enhanced by uplift; as overlying rock layers eroded away, groundwater weathering along those fracture joints created rounded corestones embedded in softer decomposed rock, and surface runoff eventually stripped away that softer material to leave the boulders exposed. The site, now a state park at 1,273 feet elevation covering 133.75 acres, was established in 1967 after geologist Dr. John Stafford Brown donated the land. This entity documents Elephant Rocks specifically as a geological formation, a field of 1.4-billion-year-old granite corestones exposed by groundwater weathering and erosion.