The complex tectonic activity in the area has created earthquakes for thousands of years. The Estuary. San Francisco Bay is one of the most important estuaries on the west coast of the Americas. Bar-built estuaries are where a lagoon or a bay is protected from the ocean by a barrier like a sandbar. An Introduction to the San Francisco Bay Estuary. By Diane Ainsworth, Public Affairs. San Francisco Bay: a 5,000-year perspective on the human transformation of the bay 13 June 2002. By Katya Kodjoian . Olympia, Washington: Washington State Department of Natural Resources. Historical reconstruction, classification and change analysis of Puget Sound tidal marshes. Importance. The Outer Banks in North Carolina is a bar-built estuary. Estuaries are the semi-enclosed coastal bodies of water where a river or lake’s freshwater and the ocean's saltwater is diluted and mixed. Save the Bay, San Francisco Estuary Project, San Francisco Estuary Institute. Its water quality is controlled primarily by streamflow from the Sacramento and San Joaquin rivers.

Fjord estuaries are created by glaciers. The San Andreas fault is on the coastal side of the bay, where it meets the Pacific Ocean at a strait known as the Golden Gate. Estuary (ĕs’chū-ĕr’ē) – a partially enclosed coastal body of water, having an open connection with the ocean, where freshwater from inland is mixed with saltwater from the sea.Estuaries represent some of the most sensitive and ecologically important habitats on earth. San Francisco Bay is a tectonic estuary. Human habitation of the shoreline of San Francisco Bay is as old as the bay itself - even older. A third type is a bar-built estuary. In fact, freshwater inflow from the Sacramento-San Joaquin Delta explains 86% of the salinity variability at the mouth of the San Francisco Bay estuary [Peterson et al., 1989]. Our estuary is radically altered from its condition 150 years ago: over 85% of historical wetlands lost to development, mercury and other contaminants remain as relics in the sediment, and the swell of human inhabitants brings other impacts such as increased atmospheric carbon and imported invasive species.

The San Francisco Bay lies at the junction of the San Andreas fault and the Hayward fault. The Human Impact on the Floridian Estuary in Tampa Bay. The last type of an estuary is fjord estuary. California's San Francisco Bay is a tectonic estuary. Collins, B. D. & A. J. Sheikh (2005).

In Alaska, Puget Sound is a fjord estuary.