With each quake along the San Andreas Fault, Bolinas Lagoon subsides a little, allowing more seawater to pour in. When sediments are flushed out more efficiently the lagoon's estuarine nature is reinvigorated. Thus, the cycle of quakes has worked to prolong the life span of Bolinas lagoon, and for millennia, the processes of scouring and tectonic subsidence have balanced the process of sedimentation. Geographical Uniqueness Bolinas Lagoon is unique geographically as well as geologically. Coastal wetlands are a rare habitat on the West Coast, and of those that still occur, Bolinas Lagoon is one of the most pristine.
Wetlands characterize the East Coast of North America, geologically a partially submerged plain.
Tidal marshes occur in most low-lying areas, and the many rivers, fed by abundant rainfall, generate estuaries both large and small up and down the coast. Though most wetlands on the East Coast have been destroyed or heavily modified by man, many remnant marshes remain. In contrast, the arid west produces few rivers to meet the sea. And, unlike the soft sediments typical of much of the East Coast, the Pacific Coast is largely rocky. As a result, the few estuaries that have formed at river mouths are contained within a small space, with the notable exception of San Francisco Bay.