The Punchbowl Formation is a sedimentary sandstone formation in the northern San Gabriel Mountains above Antelope Valley, best exposed in the walls of Devil's Punchbowl. It preserves river and alluvial deposits from the middle to late Miocene, with fossils spanning roughly 5 to 10 million years ago into the lower Pliocene. In the Punchbowl Block, the formation includes about 1,500 metres of conglomerates, sandstones, and minor mudstones. Its most notable feature is intense deformation by three faults, especially movement on the Punchbowl Fault near the San Andreas Fault, which folded and uplifted the rocks into a dramatic plunging sandstone syncline. It is important both for its visible tectonic structure and its Neogene fossils.