A long strip of mountains, the Coast Ranges, lines most of the U.S. Pacific shoreline from Canada to the Los Angeles Basin. The Coast Ranges were formed by shifting tectonic plates, which thrust the edge of the continent upward. As the mountains rose, the rivers continued cutting their way to the sea. At the end of the ice age, the melting glaciers caused the sea level to rise, flooding the mouths of rivers and creating estuaries. San Pablo Bay and the San Francisco Bay are both estuaries formed at the mouth of the Sacramento River. Upriver, low hills that surrounded the stream are now islands.
     The San Andreas Fault, the longest continental fault on earth, follows much of the Pacific shoreline, veering into the ocean north of San Francisco. The movement of the earth's crust along this fault created a long, low rift valley, which eventually filled with water. The elevated land formed a peninsula jutting into the Pacific Ocean. Most of this peninsula is contained in Point Reyes National Seashore, a 100-square-mile area of white cliffs, flat beaches, rocky escarpments, colorful meadows, and scenic waterfalls, about 30 miles south of Forestville.
     The Pacific currents are strongest in winter and summer. During this period, warm water from rivers mixes with the ocean current to create fog banks. From the hilltops and high rises of the Coast Ranges, the cool, foggy ocean air can be seen flowing through the narrow passes of the Golden Gate, Tomales Bay, and the mouth of the Russian River.
     During the long summers, the fog supplies sustenance to the coastal redwood groves. Redwood trees thrive in deep coastal canyons sheltered from the sea winds. The redwoods grow in groves in 20-mile-wide strips, rising to 360 feet above dense growths of ferns. A typical redwood tree has a life span of 400 to 2,500 years. When a redwood is cut down or burned to the ground, the roots are able to reproduce a new tree. Most of the coastal redwoods that exist today are the offspring of trees that stood 30 to 40 million years ago. The first railroads in California were laid on redwood ties. Today, fine California wines are kept in rewood vats to preserve the natural flavor of the grapes.

(Portions of this page were excerpted from Destinations, by Dennis L Foster, McGraw-Hill.)