Enchanted Rock State Natural Area sits on Big Sandy Creek on the border of Gillespie and Llano counties in the Texas Hill Country. It is 18 miles north of Fredericksburg. The Nature Conservancy of Texas purchased the property from Charles Moss in 1978. It later sold the 1,640.5-acre property to the state of Texas. The state bought an additional three acres to add to the park.Enchanted Rock opened as a state natural area in October 1978. It is a National Natural Landmark, and is on the National Register of Historic Places as an Archeological District.
Enchanted Rock rises 425 feet above the base elevation of the park. Its high point is 1,825 feet above sea level, and the entire dome covers 640 acres. One billion years ago, this granite was part of a large pool of magma, or hot liquid rock, perhaps seven miles below the earth’s surface. It pushed up into the rock above in places, then cooled and hardened very slowly, turning into granite. Over time, the surface rock and soil wore away.Those pushed-up areas are the domes you see in the park: Enchanted Rock, Little Dome, Turkey Peak and others. The domes are a small and visible part of a huge underground area of granite, called a batholith. The Enchanted Rock Batholith stretches 62 square miles; most of it is underground. Although Enchanted Rock appears to be solid and durable, it continues to change and erode.
Enchanted Rock is an exfoliation dome (as are the other domes here). That means it has layers like an onion.After the rock and soil on top wore away, the granite expanded slightly because there was less weight bearing down on it. That expansion caused the dome to split into curved sections. As the outer layer of rock breaks into smaller pieces and slides off, the next layer begins to peel away from the dome. This is a process that continues today.