Biology Reference
In-Depth Information
But most of the bay, which encompasses 470 square miles of open water
between the narrows of the Golden Gate and the Carquinez Strait, is less
than 12 feet deep. From one end to the other, the bay is about 42 miles
in length and ranges from 5 to 13 miles in width. Before radar and sonar,
ships regularly hit the fog-obscured rocks at its entrance. And gold-
seekers abandoned so many vessels of the tiny town of San Francisco that
new residents built right on top of them. These opportunists became the
first in a long line of Bay fillers who saw more dollar signs along the water-
front than up in the mother lode.
Today, 7 million people live on the shores and hills surrounding San
Francisco Bay. Around this extraordinary natural harbor, they and their
predecessors have built 46 cities, 6 ports, 4 airports, and 275 marinas, not
to mention myriad industrial centers, oil refineries, and military bases.
They have also set aside miles of bayshore for recreation and wildlife in the
form of 135 parks, refuges, and reserves.
To locals, the bay is a breathing space, a blue prairie of water outside
their windows and beside their communities. To tourists, it's the water
under the Golden Gate Bridge, the rippling backdrop to one of the engi-
neering marvels of the West.
San Francisco Bay is an estuary where rivers draining 40 percent of Cali-
fornia's landscape meet and mix with the Pacific Ocean; where coastal and
inland ecosystems overlap; where seabirds and songbirds ply the skies;
where sharks swim with sardines; and where species both native and alien
compete for space and food alongside some equally competitive primates.
Here at the edge of the North American continent, cool ocean water
and air encounter their warmer inland counterparts, shaping an environ-
ment in constant flux. One minute the sun may blaze down from above,
whereas the next is wet with fog drip. Tides coming in may suddenly go
out; wave trains may collide, encountering a shifting breeze or a change of
current; and brown plumes of sediment-laden fresh water from the rivers
upstream may dissolve into the bluer bay just west of the Carquinez Bridge
or drive a muddy arrow through the Golden Gate and out to the Farallon
Islands.
In this coastal zone, the continental and oceanic plates of the planet
can shift against one another at any moment, sending a bridge or levee
collapsing into the water. It can grow hot and dry enough for fire to con-
sume most of Angel Island in one night, and cold enough for snow to stick
on Mount Tamalpais. El Niño and La Niña rearrange the water layers
