The Tick Canyon Formation is an Early Miocene geologic formation in the Sierra Pelona Ridge of California’s San Gabriel Mountains, named for nearby Tick Canyon. Composed mainly of green sandstones, coarse conglomerates, and red claystones rich in volcanic clasts, it records an inland landscape shaped chiefly by streams rather than the sea. In the local sequence it lies above the Vasquez Formation and below the Mint Canyon Formation, and north of the Tick Canyon Fault its beds are nearly vertical. Its significance also lies in its Lower Miocene vertebrate fossils, including mammals and birds, which make it an important source for understanding southern California’s geology and ancient life.