San Francisco in San Francisco City and County, California — The American West (Pacific Coastal)
20,000 Years Ago
(text on the horizontal surface)
20,000 years ago you could have walked to the Farallon Islands...
When the sea was more than 300 feet below its present level, a marshy delta extended to the coastline 30 miles west, past the Farallon Islands. The great basin that would hold San Francisco Bay evolved from a valley carved by an ancient river carrying torrential runoffs from the uplifted granite range of the Sierra, long before Sacramento or San Joaquin had been so named. Creating the straits we call Carquinez, the river scoured the rugged valley floor to grind its way to the ocean. On the valley floor, smaller spring-fed streams cut between upthrust rocky points and ridges; thousands of years later Spanish explorers name them: Alcatraz, home of pelicans; Yerba Buena, a fragrant good-tasting herb; and Tiburon, shaped like a shark.
Dwellers of the Ancient Valley...
The cooler, wetter climate was more like that of the northwest California today. Thick forests of oak, pine, and fir covered the slopes of the western hills, and stands of redwood filled the narrow valleys - home to deer, bear, giant ground sloth, mastodon, and wolf. In the great valley
The Landscape of the Valley Floor...
The course of the ancient Sacramento River turned south as it met the last line of western hills (now the eastern shore of Marin), flowing into the northern end of the great natural trough that would become San Francisco Bay. The river ran in a deep narrow valley close to these steep western hills, and broke through this last barrier at a gap that we call the Golden Gate. Free of the hills, the river crossed a broad, low coastal plain to empty into the sea near the surf-pounded granite cliffs - now the Farallon Islands. Low rolling grasslands covered the floor of the great trough with more hills rising beyond. A few wooded hills rose above the bunch-grasses like islands, and moving in between, murmuring streams bordered by alders, and willows wound lazily through to join the ancient river.
Legend Told of a Great Shaking
Mountains split, sea water rushed in, filling the ancient valley to make a vast inland bay. Geological truth is more complex. About 15,000 years ago, as the earth warmed, the glaciers of the world began to melt. The level of the sea began to rise, and over the next 10,000 years ocean waters gradually drowned the immense inland valley of the ancient river. Filling first the deepest canyons of the great river, the sea crept up until it reached a point 381 feet above the river's bedrock at the narrow entrance to the bay. By possibly 10,000 B.C., invading salt water had moved through the Berkeley Hills at Carquinez Canyon and spread to the lowlands of the Central Valley. San Francisco Bay was of age, ready for the coming of man.
In most of the earth, fog is a dark, disagreeable smudge that comes from
nowhere...In San Francisco the fog is a thing of beauty and wonder, a daily drama of the elements
with the wide bay as the central stage. It is the mystery of imagined happenings,
the suspected drama of half-seen coming and goings, of ships and shadows and men moving
like ghosts in the billows. Like the bay itself, our fog is born of the violent meeting of land
and sea at the place where the ocean breached the western mountain
continent's edge. It is conceived out of the cold oceanic deeps and the fertile heat
of the Central Valley. It is shaped and given substance by the rotations of the planet and the
drift of the currents and the flowing rivers of atmosphere."
Erected by San Francisco Art Commission for the Waterfront Transportation Projects.
Location. 37° 47.487′ N, 122° 23.367′ W. Marker is in San Francisco, California, in San Francisco City and County. Marker can be reached from The Embarcadero near Folsom Street, on the right when traveling west. Touch for map. Marker is at or near this postal address: 327 The Embarcadero, San Francisco CA 94105, United States of America.
Other nearby markers. At least 8 other markers are within walking distance of this marker. Captain Shorey (within shouting distance of this marker); Fast Tides, Frisky Winds & Wet Sails (within shouting distance of this marker); Folsom Street (about 400 feet away, measured in a direct line); Fireboats on the Bay (about 500 feet away); Howard Street (about 600 feet away); Hills Brothers Coffee (about 700 feet away); Harrison Street (about 800 feet away); The Big Strike (approx. 0.2 miles away). Touch for a list and map of all markers in San Francisco.
More about this marker.
Categories. • Natural Features • Paleontology •
Credits. This page was last revised on June 16, 2016. This page originally submitted on March 3, 2016, by Barry Swackhamer of San Jose, California. This page has been viewed 240 times since then and 35 times this year. Photos: 1, 2, 3, 4, 5, 6. submitted on March 3, 2016, by Barry Swackhamer of San Jose, California.