The valleys along the Santa Barbara coastline run east to west rather than north to south, resulting in ocean breezes that sweep through the region in a rare eastward direction. This geologic oddity provides a patchwork of microclimates and terrains, resulting in one of the most diverse grape-growing regions in the United States. The Santa Maria Valley, the county’s northernmost AVA and most famous, has the majority of its vineyards planted on elevated plateaus along the Santa Maria River mesa and Sisquoc River drainage. The soils are typically of marine origin and sedimentation from river wash.