Devils Thumb

Named for the protruding natural hot spring cone, this rock's grayish appearance is in stark contrast to the bright orange travertine terraces it rises out of. The water flows in a crisscross pattern, surrounding the protrusion and adding mineral deposits around it. Devil's Thumb is a very short walk from the Lower Terrace Trailhead parking lot off of Grand Loop Rd. There's a boardwalk for your safety and for the preservation of the park.