Mammoth molar found on bay beach holds clues


Ornithologist and Alaska transplant Sarah Warnock made a special find during a recent walk on the beach in the Cypress Grove Preserve: the molar of a mammoth. She knew what she was looking at because she had seen it before. 

“Up in Alaska, with the permafrost melting, people are finding more and more mammoth fossils: I’ve known people who have found them,” said Ms. Warnock, who recently moved to the Tomales Bay preserve when her husband took a job with Audubon Canyon Ranch. “When I touched it, I realized it was bone, that it was a fossil. It was so organic looking, I knew it was a molar or a tooth. It had the pointy part, the roots of a tooth.”

The artifact is the first of a mammoth found on the shores of Tomales Bay, though it’s not unheard of in the area: mammoth remains have been discovered nearby, including in Bodega Bay, where a tusk and lower jaw with an attached tooth were found near Bodega Head in 1972.

James Allen, a licensed geologist and paleontologist, helped Ms. Warnock examine the fossil and is excited about what it might reveal about the history of the bay. 

Mr. Allen explained that the molar was found in the rocks on the beach below the tideline, sandwiched between what he has determined to be two very disparate geological layers: native clay that is representative of a freshwater lake or pond system and cobble conglomerate typical of much faster moving water, like a river. 

He’s waiting on lab results to determine the exact age of the molar and the species of the mammoth. That information will help provide clues to the events that altered the geology where the fossil was found. 

“Once the age comes back, there’s a few scenarios,” he said. “It could be tied to a tectonic event being so close to the San Andreas or what appears to be a climate-change warming event based on the stratigraphy it is in.” It could have been a quake—the San Andreas fault runs through what is now Tomales Bay—or the inundation of coarse gravel caused by melting glacial water filling into the bay when the last ice age ended around 11,700 years ago.

The bay likely did not fill just once, but a few times with warming events, he said. 

Ms. Warnock, who said she’s had a lifelong fascination with paleontology, shared a vision of what the mammoth’s world might have been. “During the last glaciation period, the ocean levels were so low—the coast began out by the Farallones, which were hills then—and a mammoth could walk through Tomales Bay, which was just a valley then,” she said. “They would walk through that valley out to find food on the grassy coastal plain, which stretched 12 miles out to the water.”

The two scientists, along with several interested researchers, are hoping the lab results paint a fuller picture of their discovery, which is currently sitting in an ice chest in Ms. Warnock’s garage.

They will also find out the species. Both main species of mammoths, Columbian and woolly, are thought to have died out during the last ice age. Though Columbian was the more common type, the molar is suspected to be a Woolly.

The woolly mammoth was roughly the same size as modern African elephants: males reached shoulder heights of up to 11 feet and weighed up to 8 tons, according to a database provided by National Geographic. Adapted to the cold environment, woolly mammoths had a thick fur coat—with both long, coarse exterior hair and a short, dense layer underneath—and short tails to reduce heat loss and prevent frostbite.

It had long, curved tusks and four molars, which replace six times during a lifetime. It probably used its tusks to brush away snow in search of food, to deter potential predators, and to attract mates. The mammoths ate plants, grasses, aquatic shrubs and trees, and its habitat—called the “mammoth steppe”—spanned from Spain eastward across to Canada and from the Arctic islands southward to China. The local range is sometimes referred to as the “California Serengeti,” where herds of mammoths, mastodons, camels, horses, llamas, elk, tapirs, moose and bison roamed.