NARRATOR
If you were standing here at Salesforce Park in the 1850s, you could have gazed at the massive 80 foot high sand dune that stood near Second and Howard streets. Before the Gold Rush, at least a dozen square miles of the San Francisco peninsula was covered in sand dunes. This was rather unusual in California, says Sean Baumgarten, landscape ecologist at the San Francisco Estuary Institute.
SEAN BAUMGARTEN
Historically, it was one of the most extensive dune complexes on the California coast.
NARRATOR
Baumgarten learned about San Francisco's sandy past through a process called historical ecology, which involves research on hundreds of old maps, photographs ,and written accounts to recreate a picture of the ecosystems and waterways that existed in San Francisco before Spanish colonization. When it comes to sand dunes, Baumgarten says there were two main types. The first were those that looked like classic open dunes with lots of exposed sand.
SEAN BAUMGARTEN
On the western side of the peninsula, it was more large areas of bare sand and then clumps of vegetation.
NARRATOR
Because the ever-present winds from the Pacific Ocean constantly blow sand across the peninsula, these mobile dunes would gradually migrate.
SEAN BAUMGARTEN
Two maps about 20 years apart in the 19th century showed how much the mobile dune field had shifted over that time. In some areas, it was several hundred feet.
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The second type of dune in San Francisco was the stabilized dune. These older dunes were held in place by the roots of various grasses and scrub plants. In 1857, geology writer William P. Blake wrote, "Most of the hills where they were partly sheltered from the wind are or were covered with a thick growth of dwarf trees and shrubs, which prevented the wind from acting upon their surfaces and removing the sand." As San Francisco Estuary Institute landscape ecologist Lauren Stoneburner describes:
LAUREN STONEBURNER
There were accounts of vegetation being removed from sand dunes, especially on the eastern side of the city near Yerba Buena Cove. And when the sand dunes were destabilized when the vegetation was removed, those sand dunes began to move.
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Early settlers of San Francisco found the blowing sand a great nuisance to their efforts to build and expand the city. In 1849, Edward Cheever wrote:
HISTORIC QUOTE
"The winds swept across a series of sand hills with such force that at times, the sand was driven in clouds along the main traveled roads. I noticed that horseshoes and pieces of metal lying on the surface were smooth and brightly burnished by the patricians of the sand."
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But over many decades, buildings eventually triumphed over the dunes and the sand from those hills was quickly put to use, says Sean Baumgarten.
SEAN BAUMGARTEN
As the city developed and expanded, the dunes were built over in many cases. They were intentionally leveled, so the sand was taken to fill in Yerba Buena Cove and other parts of the shoreline.
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Developers needed flat land to build upon. So a man named David Hughes devised a system for relocating dune sand. Steam shovels would dig sand from a hill, railroad cars and engines would haul it to the shoreline where men with shovels would dump it into the Bay, filling in the shallow waters to create new land. Hughes managed to get paid both for removing the sand and for filling the Bay. His system could move more than 2.200 tons of sand each day, and between 1858 and 1869 it reshaped San Francisco, flattening its hills and filling nearly all of the open water in Yerba Buena Cove in Mission Bay. It's still possible to find the sand in San Francisco if you know where to look. Residents of the outer Sunset District know that without constant effort sand dunes would invade their neighborhood.
SEAN BAUMGARTEN
You wouldn't see sand dunes starting to form again. And in fact, we do see that in areas like the Great Highway where there'll be sand drifts that form and blow across the highway.
NARRATOR
Mobile sand dunes can be found all along Ocean Beach, while stabilized dunes covered in plant life can be found along the western margins of the Presidio. But where did these dunes come from? Continue on to the next track to learn more.
