Just north of Hub Junction on Fire Road 30 is this exposure of the Santa Susana Formation that was deposited on top of the Tuna Canyon Formation. The rock is mostly a greenish-brown siltstone like is shown in the bottom part of the photo, but the formation also contains lenses of white limestone like the one in the top-center. The limestone is composed of the skeletons of calcareous algae, plants that can live only in marine water that is shallow enough for sunlight to penetrate. Other fossils in these rocks show that they were deposited during the late Paleocene epoch about 55,000,000 years ago.
|
