Physical characteristics...

Tomales Bay is a 6800 acre estuary located on the central California coast approximately 40 miles northwest of San Francisco. It is twelve miles long and relatively shallow, occupying the seaward end of a rift valley created by the San Andreas fault. This fault lies underneath the bay and below Highway I, which parallels the east side of the bay.

Most of the surrounding hills on the east side are composed of Franciscan formation soils while along the west side are various outcroppings of granite, further evidence of the fault action which is moving the Point Reyes peninsula.

The Tomales Bay watershed occupies an area of approximately 219 square miles (140,00 acres, 142 perimeter miles.) The northern end of the bay opens to Bodega Bay and the Pacific Ocean while the southern end is fed by Papermill Creek and marked by wetlands. Black Mountain rises at the southern end of the bay above the community of Point Reyes Station.

The west side is characterized by the Bishop pine and Douglas Fir forested Inverness Ridge. The communities of Inverness and Inverness Park provide a variety of services along the main driving route, Sir Francis Drake Highway.

In contrast, the east side is open oak woodlands and grasslands with dairy and beef ranches. The main driving route is State Route 1 which is immediately adjacent to the bay. Along the east side Point Reyes Station and Marshall provide services.

Tomales Point and the surrounding hillsides were not traditionally forested, stands of non-native Monterey Cypress trees and "Blue Gum" eucalyptus trees were planted on the Point and along the shores of Tomales Bay and on Hog Island to shelter pioneer settlements and summer residences.

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