The CCNM comprises a variety of geologic and topographic features. Some of the islands off the coast and their surrounding rocks and islands were formed through igneous processes—plutonic and volcanic activity. Other nearshore rocks and islands are sedimentary or metamorphic in formation, the result of deposition of geologic material over time, and in some cases, subsequent modification by pressure and heat. The rocks and small islands contained in the CCNM are always changing due to geologic processes—some of these rocks became separated from the mainland because of erosion from wave, wind, and tidal action, and these forces will eventually erode certain islands and rocks below mean high tide, and cause other areas currently attached to the shoreline and larger islands to eventually become separated. These features make up the topmost portion of the outer continental shelf, which extends westward of California for four to five miles; during the Pleistocene Epoch, the shelf was exposed above sea level, defining California’s prehistoric coastline some 20,000 or more years before present (BP). 

 

In general, wind and wave action have also determined the physical characteristics of the coastline and its associated CCNM features. North of Point Conception (in Santa Barbara County), strong waves and wind have worked on the California Coastal Range formations to form numerous offshore rocks and islands. South of Point Conception, however, the coastline is more protected from the impact of storm waves by large offshore islands (i.e., the Channel Islands). The formations of the Transverse and Peninsular Ranges of the south coast have produced fewer rocks and islands. 

 

The biological resources of the monument are influenced by these physical characteristics, as well as other processes such as climate and ocean currents. Climate along the coastline of California varies, with cooler temperatures, more rainfall, and more extensive cloud cover in the northern portion of the state. Conditions become milder in a continuum southward. The California current, carrying water cooled by its passage through the northern latitudes, flows southward along the shore from the Washington–Oregon border to Southern California, and brings nutrients and biota into the coastal waters¹ surrounding the CCNM.

 

These rocks, small islands, exposed reefs, and pinnacles are the homes and breeding grounds of many marine and terrestrial species including birds and marine mammals. The rocks support a diverse assemblage of rocky intertidal zone plant and animal species. In the area spanned by the CCNM, people enjoy recreational activities such as fishing, kayaking, wildlife viewing, scuba diving, and snorkeling. The CCNM is also of aesthetic and economic value to coastal communities because the rocks and islands provide beautiful scenery for local residents and visitors, as well as a focal point in a vast ocean viewscape. While the CCNM comprises, and its direct management addresses, only those portions of the rocks and islands above mean high tide line, the monument features are a part of a larger coastal and marine ecosystem which both depends upon and supports the CCNM.