Most of the fossils uncovered at the Calaveras Dam replacement project in Fremont, California, are believed to be about 20 million years old, dating to the Miocene Epoch, when the ocean extended as far inland as Bakersfield, California, the San Jose Mercury News reported on Monday.
Scallops, clams, barnacles and the teeth of an extinct hippopotamus-like creature called a Desmostylus have all been dug up since 2011, when work on the project began.
"We started finding fossils here before construction even started," paleontologist Jim Walker, who is working alongside construction crews on the project, said. "It was exciting. We were finding scallops, and I said, 'I want to get a whale.' And we did."
Crews have discovered nine whale skulls. Plant fossils and fossils of animal tracks and burrows have also been discovered.
The $700 million dam replacement project is part of a 15-year, $4.6 billion upgrade to the Hetch Hetchy water system, which relies primarily on the Hetch Hetchy Reservoir in Yosemite National Park and serves about 2.6 million customers in the San Francisco Bay Area.
The reservoir created by the Calaveras Dam is among several local reservoirs that supply the region. The dam, completed in 1925, is being replaced with one more capable of withstanding earthquakes.
Crews are currently removing earth in front of the dam, the Mercury News reported. Construction on the new dam itself, which will go up about 400 yards downstream, is expected to start in 2016, with completion expected two years later.
Paleontologists will continue working with construction workers for the next few years. The fossils eventually will end up at a museum in the Bay Area, according to officials from the San Francisco Public Utilities Commission, which is building the dam.
Information from: San Jose (Calif.) Mercury News, http://www.mercurynews.com
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