Читать книгу Afoot and Afield: San Francisco Bay Area. A Comprehensive Hiking Guide онлайн

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Within the Bay Area are sub-ranges such as the Sonoma, Mayacmas, and Vaca mountains in the North Bay; the Diablo Range in the East Bay and South Bay; and the Santa Cruz Mountains on the Peninsula and in the South Bay. The tallest peak in the North Bay is Mt. St. Helena (4343’), at the corner of Sonoma, Napa, and Lake counties. Other prominent Bay Area summits include Mt. Hamilton (4213’), Mt. Diablo (3849’), Loma Prieta (3806’), Mt. Tamalpais (2571’), and Sonoma Mountain (2295’).

Olcott Lake in Jepson Prairie Preserve, a seasonal pool, hosts a variety of plants and animals, some quite rare.

Most of the surface rock in the Bay Area is sedimentary, but volcanic activity has occurred here in the past. Young volcanic rock caps the Mayacmas and Vaca mountains bordering the Napa Valley, and there are four extinct volcanoes in the East Bay, including Round Top (1763’). California’s state rock is serpentine (more properly, serpentinite), gray-green in color and often seen as outcrops beside the trail. Serpentine forms a soil that is toxic to many plant species, but some have adapted to it. Among these are Sargent cypress, leather oak, and a variety of uncommon wildflowers.