Geologic Formations

Santa Ynez Mountains

The Santa Ynez Mountains represent the western portion of the Transverse Range which runs in an east - west direction. The crest of the Santa Ynez Mountains tilts sharply to the south and you may notice this in the lines of the rock strata.

	The Juncal Formation is the oldest rock formation and is made of sandstone and shale formed about 50 million years ago and averages 4500 feet in thickness. This formation is best seen in the Red Rock region and the upper Santa Ynez Valley.
	Cozy Dell Shale is derived from a fine sea mud deposited about 37 million years ago. This shale is exposed along the saddle between La Cumbre and Cathedral Peaks and also on the connector trail between Rattlesnake and Tunnel Trails.
	Matilija Sandstone was formed next in geological time by weathered granite particles accumulated as a layer of sand on the ocean bottom. Its hardness has made it less prone to erosion than other formations. It is best visible in the upper part of the San Ysidro Trail and near La Cumbre Peak.
	Coldwater Sandstone is buff-colored and contains mollusk fossils in its upper layers. The upper Jesusita Trail and the Cold Springs Trail contain this sandstone.
	Sespe Formation is a mixture of shales, sandstone, and conglomerates, and contains iron oxides which give it its red color. Outcrops are visible on the Jesusita Trail and in the Montecito Foothills.