Maritime scrub vegetation thrives in the sheltered valley of Abbotts Lagoon (located along the Pacific shore of the peninsula north of the Point Reyes Headlands). This view is from along the Pierce Point Road. Abbotts Lagoon is a stream valley that has been flood by the rise of sea level caused by the melting of the continental ice caps after the last glacial maximum. Coastal migration of sand has built up a large beach and barrier island and dunes across the mouth of the flooded stream valley. The hill to the left of the lagoon consists of Monterey Formation capped by Santa Margarita Sandstone. Coastal dunes make up the hills to the right of the lagoon.