Unit is named the Marple Canyon Sandstone Member of the Ridge Route Formation of the Ridge Basin Group. Is exposed in the central Ridge basin, Los Angeles Co., CA. Is the oldest of five major clastic tongues in the Ridge Route Formation. Consists of brown and white arkosic sandstone interbedded with mudstone and conglomerate, and contains freshwater mollusk, ostracode, charophyte, and vertebrate fossils. Lateral extent is 8000 m; interfingers with the Castaic Formation; conformably underlies the Paradise Ranch Shale Member (new) of the Peace Valley Formation (revised). Thickness is 420 m at the type section and ranges from 80 to 1,100 m. Age is late Miocene (late Mohnian) based on its stratigraphic position above the Castaic Formation. (B1565)

Source: GNU records (USGS DDS-6; Menlo GNULEX).