This aptly-named hilltop park in the Sunset District has stunning views stretching from downtown San Francisco and Golden Gate Park to Pt. Reyes and around to Lake Merced. The park features a dune plant community atop 140-million-year-old rock called Franciscan chert, which was first formed when the region was part of the ancient sea floor. Most carbonate shells dissolve in ocean waters before they reach the sea floor, but radiolarian shells are silica-based and do not readily dissolve. Millions of years ago, countless radiolaria combined with mineral dust blown from inland deserts to form layers of chert, which were later uplifted to land.