Shifting Shoreline

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You are standing on the shoreline. You can't see the Bay waters now. But if you could look back in time to the early 1800s, you'd be gazing out over a shallow inlet from San Francisco Bay, Yerba Buena Cove. Named after a locally abundant herb, Yerba Buena Cove encompass some 35 square blocks of what is now downtown San Francisco. Today the cove has been filled in and built on and the edge of the Bay at the Embarcadero is about seven blocks away. In the days before the cove was filled, you could have waded or walked part of that seven block distance, but the trip would have been rather mucky, according to Sean Baumgarten at the San Francisco Estuary Institute.

SEAN BAUMGARTEN
There would have been at low tide large areas of mudflat exposed. Potentially at the lowest tides of the year even, you know, most of the cove being exposed. But then at high tide, they would have been covered up by the Bay again.

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What did those mud flats look like? Lauren Stoneburner, also from the San Francisco Estuary Institute, explains.

LAUREN STONEBURNER
If the mud flats were exposed by a very low tide, you would see all sorts of shorebirds that would be sticking their heads in the mud, and you might hear a little sound of them pit-patting across the mud, and you'd probably hear gulls squawking or squabbling over some this or that. And more at high tide, you would hear waves lapping generally on the beach when protected. It was this sticky mud. If you'd picked it up, it would have had this maybe sulfurous smell.

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Also right where you're standing, on the shore of the cove, you would also have seen a small lagoon, says water researcher Joel Pomerantz.

JOEL POMERANTZ
There was a creek coming down from the direction of Nob Hill. And just before it flowed into the Bay, it formed a pool of water. And then in big weather events, there would be a breakthrough and in general, it probably broke through the sand and flowed out to the Bay. But that pool of water was connected to the Bay through a very narrow channel and the bridge across that channel, Montgomery Street, was the first bridge in San Francisco.

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It was around this lagoon at the edge of the muddy cove that the first small settlement of colonizers was founded in 1835. This village, also named Yerba Buena, would eventually become San Francisco. When it was founded, the hills were mostly open and scrubby says Sean Baumgarten.

SEAN BAUMGARTEN
Inland from the cove, the vegetation was a mix of sand dunes and coastal scrub and oak woodlands and those oak woodlands were dominated by coast live oak and it was a special form of it—a dwarfed form of coast live oak. So these trees were stunted by a combination of the winds and the infertile soils and the low water availability and then they would have been intermixed with the surrounding scrub, the coastal scrub, which supported plants like coyote brush and monkeyflower and coffee berry and things like that.

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Given the hardscape that surrounds us today, it's hard to imagine such a bucolic setting. So how did Yerba Buena Cove undergo such a transformation? How did all that water in the cove turn into land? It all traces back to ships. Nearly all the people and all the goods that arrived in the growing town in the mid 1800s got here on large sailing ships. The Cove was far too shallow for those big ships to navigate. Marine archaeologist Jim Delgado explains how the city dealt with this problem.

JAMES DELGADO
In order for ships to reach port and safely discharge their cargoes you had a couple of options. You could load everything into boats or a flat bottom to lighter or a barge and ferry it ashore. But the easiest thing to do was to build a pier, a wooden pier that could stretch out over the mud flats regardless of the tide and how high or low it was, upon which ships could discharge and loaded in carts goods, light and heavy, could be brought ashore and then distributed sold into the local market.

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Over time, as merchants built more piers, the city decided to take advantage of the open water alongside them. Just as one might sell plots of open land, the city subdivided Yerba Buena Cove into water lots and auctioned them off to the public. In a city with almost no flat land, investors knew these lots would be valuable if they were turned into land. So as soon as the first water lots were auctioned—444 of them in March 1847—the new owners began filling them by dumping sand and rocks, burnt debris from fires, and even unused sailing ships. To reach these lots, they also built more piers extending into the cove says Jim Delgado.

JAMES DELGADO
In 1849 to 1851, it literally was a criss-crossed maze of wooden wharves on pilings with building sometimes two or three stories high also on pilings, and intermixed in between floating ships.

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The filling of Yerba Buena Cove continued, as did the selling of water lots, until 1859 when the cove was enclosed by wharves and almost completely filled in. Much of the filling work was done by steam shovel, known locally as a Steam Paddy, which excavated dune sand to fill in the coves. You can hear more about that at stop number 10, City of Sand Dunes.

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 If you could look even farther back in time, 18,000 years ago, you wouldn't see Yerba Buena Cove at all, nor any part of the San Francisco Bay. It didn't exist according to geologists. Instead, a river flowed through what's now the middle of the Bay, then out through the Golden Gate meeting the ocean some 30 miles to the west. The Farralon Islands were then high hilltops near the shore. 18,000 years ago was the middle of the last ice age. Much of the Northern Hemisphere was covered in massive glaciers and ice sheets. And with so much water trapped in the form of ice, sea levels were much lower than they are today. But during the next few 1,000 years, temperatures started to rise and all that ice started to melt. Sea levels began to rise about three centimeters or more than an inch per year on average. As Ohlone historian Gregg Castro explains, the Bay Area was a much different place when people first arrived.

GREGG CASTRO
Sea level was very different. There was a time when it was a walkable marsh, perhaps, and wetlands that you could traverse without having to go all the way around, didn't need bridges. You just go right across. You could go to the islands; Alcatraz was probably a hill at that time used probably for ceremony.

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The ocean shoreline moved steadily eastward until about 8,000 years ago when the rising waters pushed through the Golden Gate and began to flood the wide river valley forming San Francisco Bay.