UC Berkeley Web Feature
Elephants in San Jose?
BERKELEY – On his knees in a muddy ditch less than a mile from the San Jose airport, Mark Goodwin was oblivious to the planes roaring overhead every 10 minutes, the joggers slogging by on the levee trail and the merely curious pressing their noses to the chain-link fence.In an A's cap and shorts in the hot sun, Goodwin methodically removed clod after clod of sandy clay with a hammer, slowly revealing the bones of one of the city's earliest residents, a mammoth.
Goodwin, assistant director of the University of California Museum of Paleontology at UC Berkeley, was on site recently with two graduate students to excavate the bones and perhaps learn a bit more about these prehistoric denizens of the Bay Area. He has been involved with the excavation on Santa Clara Valley Water District land since mid-July, after a truck mechanic discovered the bones and alerted the museum.
"San Francisco Bay has a rich fossil history, especially from the Pleistocene age," Goodwin said. "A lot of mammals no longer around today in North America - elephants, camels, rhinos, sloths, saber-toothed cats - roamed through the region tens of thousands of years ago."
While mammoth fossils are not uncommon, however, it's relatively rare to find many bones together from the same individual, he said. So far, he has tentatively identified a femur or upper hind leg bone; portions of the skull, with a pair of tusks; a pelvis; a rib fragment; and possibly a few foot bones. When the water district drained the ditch to allow his crew to dig, another fossil- a partial humerus, or upper front leg bone, of another mammoth - was exposed.
Goodwin says the mammoth was a Columbian mammoth, Mammuthus columbi, a relative of the elephant and a less hairy cousin of the more northerly woolly mammoth. Mammoths migrated to North America about 2 million years ago, lived in the Bay Area during the Pleistocene and went extinct around the world about 11,000 years ago.
"There are other fossils in this watershed," he added.
The mammoth find surprised many geologists, who thought that local sediments were around 5,000 years old. The sediments must be at least 11,000 years old, however, since that's when mammoths died out, said Goodwin. He is working the site with San Jose State University geologists who hope to find carbon in the sediments that will help assign a carbon-14 date to the mammoth, in case the mammoth bones themselves cannot be dated.
The discovery also has galvanized the public. Parents with children, police, joggers and many other local residents have been stopping by the site to check up on the excavation. And every local newspaper, radio and television station has dropped in - many of them regularly - to follow what Goodwin and his students have found. The water district even mounted a Webcam at the site, viewable at mammothcam.com. Updates with dig photos are posted daily on the museum's Web site.
The fossilized bones were discovered July 9 sticking out of the mud of an algae-filled flood channel called the Lower Guadalupe River in north San Jose. Not far from Mineta San Jose International Airport, the ditch parallels a gravel-topped levee open to the public but belonging to the Santa Clara Valley Water District. San Jose truck mechanic Roger Castillo discovered the bones while walking his dog along the levee, where he had been many times in recent years to monitor the Guadalupe watershed as a volunteer for the Guadalupe-Coyote Resource Conservation District.
Because the UC Museum of Paleontology is a designated repository for any fossils found in the state of California, Castillo eventually got hold of Goodwin. Once notified by Castillo, the water district hired a 24-hour security guard for the site, and Goodwin drove down to reconnoiter on July 13. He then confirmed his suspicion that the bones most likely were those of a Columbian mammoth.
With UC Berkeley graduate students Randall Irmis and Jennifer McGuire, summer employees of the museum, Goodwin spent the week of Aug. 1 excavating around the perimeter of the fossils, covering them with burlap and plaster jackets, and then gently lifting them free of the sandy clay.
Goodwin noted that the mammoth seems small and may have been a juvenile. The wear on the bones suggests that after death, the bones lay exposed to the weather, and the pelvis seems to have been polished by flowing water. Perhaps, he speculated, the mammoth died near the river bank and was buried in clay and silt during subsequent floods.
Back at the museum, the fragile bones will be catalogued, carefully removed from their plaster jackets, cleaned up and hardened with glues and adhesives. Goodwin anticipates that the bones eventually will be loaned back to the water district or a San Jose museum for display, though they will remain the property of the paleontology museum.
"These fossils belong to the people of California and should be displayed for their benefit," he said.