A collision coast typically lies along a convergent plate boundary. However, an exception is made for coastal California. Although presently located along a transform boundary the coast of California retain features created during its collision with the Farallon plate which terminated approximately 20 million years ago. A coast located along the collision margin of an island arc, such as the islands in the western Pacific. Coasts are often associated with and affected by earthquake and volcanic activity.
Coasts are relatively straight with narrow continental shelves and steep continental slopes.
The high mountains adjacent to the coast are potentially a great source of sediment, but the narrow shelf results in submarine canyon heads that lie close to shore. Consequently most of the sediment deposited along the coast is eventually drained off through canyons. Second order features such as large deltas and barrier island chains are typically lacking on these narrow coasts. Cross section through a continental collision coast and Amero-trailing edge coasts, such as that viewed across South America. Note that the westerly divide deflects most continental drainage and consequently sediment transport towards the eastern margin of the continent.