BEACHES
 

Beaches are dynamic landforms altered by wind and waves in acontinual process of creation and erosion. Seasonal cycles of sand deposition and loss dramatically affect the appearance of beaches from summer to winter. Wide and gently sloping in summer, they become steep-fronted and narrow in winter, and cam vanish overnight, stripped of sand by violent storm waves. Most of the sand removed from winter beaches is deposited in offshore sandbars and is returned to the beach during the mild summer months by gentle swells that push the sand to the exposed shore. River sediments are the source of 80 to 90 per cent of beach sand; some beaches are built to great widths by sediments washed to the sea by episodic floods, gradually eroding until the next major flood replenishes the sand.

California's diverse coastal communities are the result of many different natural forces. Tectonic and volcanic activity, occuring over the past 250 million years, created our coastal mountain ranges. Both the Farallon and Channel Island systems are the result of similar geologic process. Coastal streams and rivers, along with wind and rain, shape and tear down these mountains through erosion. The powerful, ceaseless waves of the Pacific also cut into the coast mountain ranges and carve vertical cliffs, terraces, and bluffs into the rock. Elsewhere along the California coast, debris from wave erosion and sand deposited by streams and rivers accumulates and forms California's sandy beaches. Inland, where wind-blown sand from the beaches collects, one can find fragile systems of coastal dunes. Coastal rivers and streams meet with the salty waters of the Pacific and create the marshes and lagoons which constitute California's coastal wetlands. In other areas, abrasive sand and wave motion cut grooves and pockets into the rock and intertidal communities and tidepools form. And even below the Pacific's waters geologic forces act, through many of the same processes, on the sea floor. Click on the items below to learn more about specific features of California's coastal geology.

California Coast Route Hwy "1"