A new national park
The park's spectacular pinnacles are half of an eroded volcano. The matching half lies 195 miles (314 kilometers) to the southeast, on the other side of the San Andreas Fault. The 1976 discovery of the 23-million-year-old split volcano provides a unique geologic marker of offset along the fault. President Theodore Roosevelt established Pinnacles National Monument in 1908, to preserve its massive monoliths and wildlife. The giant spires are now a popular rock climbing destination.