Boulders of the Matilija were included in the mud and debris flows in the January 2018 Montecito mudflows. The Matilija Sandstone produces little soil when it weathers, and generally supports only hard chaparral on slopes that are not bare rock. North-facing slopes have some stands of pine and fir in the higher elevations. The formation appears in boreholes drilled into oil fields offshore, indicating the formation dips steeply underneath the Santa Barbara Channel. At the Point Conception Oil Field, the Matilija is at least thick, and first appears approximately below ground surface. In the Molino Offshore Gas Field, southeast of Gaviota about offshore, the formation is at an average of below the seafloor, and a well drilled to had not reached the bottom of the formation. Sometime in the early Eocene, around 50 million years ago, the landmass containing present-day Santa Barbara County became submerged, allowing sediment deposition offshore. During this time the sea alternately deepened and became shallow again, with the deposition environment supporting either sandstones or shales corresponding to shallow or deep conditions. The Matilija Sandstone dates from the earliest sustained shallow-water episode during this time, the period from 48.5 to 46 million years ago. Additionally, the piece of the crustal block on which the sandstone was deposited has rotated approximately 90 degrees clockwise since the time of deposition, moving from a location approximately adjacent to present-day San Diego to the region it occupies in the present day. After reaching its current position along the coast, the entire Santa Ynez Range was uplifted, mostly during the Quaternary period and late Pliocene, by crustal shortening and compression from tectonic forces at the boundary of the Pacific and North American Plates. The Matilija Sandstone and other units, formerly submerged, rose over from their original positions. In some places the forces causing this uplift were so abrupt that sedimentary layers deposited as recently as the Pleistocene are now angled 60 degrees from horizontal. While the formation is rich in microfossils, it is considered to be of low paleontologic sensitivity, i.e. larger fossils are unlikely to be encountered. In the Santa Rosa Hills, the unit has yielded numerous shells of molluscs, including bivalves and gastropods. As a potential reservoir for oil and gas deposits, the Matilija Sandstone is grouped with the above-lying Cozy Dell Shale and Coldwater Sandstone as the Gaviota-Sacate-Matilija Sandstone Play.