Construction Site Unearths Fossil Treasure Trove in Silicon Valley

Construction workers building a 220-foot-high dam at Calaveras Reservoir have unearthed a prehistoric treasure trove, revealing what Silicon Valley might have looked like some 20 million years ago.

Over 500 marine fossil specimens have been uncovered at the Calaveras Dam replacement project in Fremont, Cali. as of Monday, the San Jose Mercury News reported. Among them are teeth of an extinct hippopotamus-like creature called a Desmostylus, clams, barnacles and the giant teeth from a 40-foot-long shark - and what could turn out to be an entire whale skeleton.

Scientists believe these fossils date back to the Miocene Epoch, when the ocean extended as far inland as Bakersfield.

"This area used to be the beach," paleontologist Jim Walker, involved in the excavation, told Mercury News. "Twenty million years ago, this would have looked like Half Moon Bay."

Since the project began in 2011, crews have discovered 529 types of fossils. Of those, 168 are vertebrates, such as sharks; 267 are invertebrates, such as scallops; 39 are plants, such as fossilized pinecones; and 55 are other ancient items, from animal tracks to burrows. They also found not just one, but nine whale skulls.

"Whales like this have been found in the Bay Area before," Walker commented. "But not this many together."

The old 210-foot Calaveras Dam, built in 1925, is part of the Hetch Hetchy water system that provides 2.6 million residents with drinking water. The site is currently closed to the public due to construction, but paleontologists will continue working with construction workers for the next two or three years on the massive job to replace the dam with one more capable of withstanding earthquakes, according to the Associated Press.

Though the Calaveras Dam was the tallest earth-fill dam in the world, it was deemed seismically unsafe, and so the now $700 million, 15-year upgrade will hopefully protect thousands from being harmed should an earthquake happen.

Since the dam's construction began, workers unearthed two huge ancient landslides, as well as hundreds of fossils - which will be moved to a Bay Area museum, according to officials from the San Francisco Public Utilities Commission, which is building the dam. The project will be completed in 2018.