Ochoco Mountains made of rocks from the Permian, Triassic, and Jurassic periods (300 to 200 million years old) that were transported by the Pacific Plate and accreted in the late Mesozoic era (about 100 million years ago) as part of a vast shallow sea, then slowly uplifted by volcanic eruptions during the Eocene epoch (50 to 37 million years ago) to form the Clarno Formation. From 37 to 17 million years ago, eruptions in the western Cascade Range spread ash across eastern Oregon, forming the John Day Formation. From 17 to 14 million years ago, major volcanic eruptions covered much of the
Orcombe Point cliffs further east. The coastal exposures along the coastline provide a continuous sequence of Triassic, Jurassic and Cretaceous rock formations spanning approximately 185 million years of the Earth's history. The localities along the Jurassic Coast includes a large range of important fossil zones. Orcombe Point is the western end of the Jurassic Coast and the South West Coast Path includes the entire length of the site. The ascent to Orcombe Point shows the successive layers of different sedimentary rocks, which were deposited under varying geological conditions. At the base are cross-bedded sandstones. Towards the top, the rock types are those