The Santa Ynez Mountains are a portion of the Transverse Ranges, part of the Pacific Coast Ranges of the west coast of North America. It is the westernmost range in the Transverse Ranges. The range is a large fault block of Cenozoic age created by the movements of the Santa Ynez Fault. A very narrow range, the Santa Ynez Mountains rise quickly on its north side and drops off equally dramatically along the range's south face along the Gaviota Coast. The Santa Ynez Mountains begin as a series of volcanic hills near Point Arguello, and gradually transitions eastward into a single, well-defined ridge extending from Gaviota Peak to Matilija Creek. The range is approximately contiguous with the Topatopa Mountains beyond to the east, which terminates abruptly at Sespe Creek. The climate of the range is Mediterranean with most of the precipitation falling between November and March. Most of the range lies in the California chaparral and woodlands ecoregion. At the crest and on the north slope, the rainier regions support extensive oak woodlands, mixed with other broadleafed species such as madrone, sycamore and bay laurel, along with some conifers, primarily Coulter pines. Geography The mountains are principally in Santa Barbara County, with an eastward extension into Ventura County, and are unusual in being an entirely east–west trending mountain range—one of the few in the United States. This is attributed in part to clockwise rotations of crustal blocks 90° or more since the early Miocene or about 17 million years ago. The range is mostly within Los Padres National Forest. The southern slopes of the range drop off into a series of alluvial plains which make up the Gaviota Coast along the Santa Barbara Channel. They tend to be made up of unconsolidated riverine deposits overlying shale bedrock. The northern boundary of the range is marked by the Santa Ynez Fault, the massive thrust fault that uplifted the mountains since approximately 5 million years ago starting in the Pliocene. Notable features along the fault which mark the boundary of the range include Jalama Creek and the Santa Ynez River to the west and Matilija Creek in the far east. To the north of the range are the San Rafael Mountains. Laterally, the mountains extend from an eastern terminus at the canyon of the Ventura River and Matilija Creek, north of Ojai, west across the Santa Barbara County line, to immediately north