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Reservoir Dig Yields A Mammoth Find

Researchers have many bones to pick amid the abundant Ice Age treasures of California's 'Valley of the Mastodons'

By Peter N. SpottsStaff writer of The Christian Science Monitor / July 29, 1997


Drinking deep draughts of diesel fuel, canary-yellow behemoths dig their steel buckets deep into the valley floor.

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The shovels, which drop 36-ton loads of soil into trucks the size of a two-story house, are not merely digging the foundation for a dam at the Eastside Reservoir Project here. They are burrowing back through time, opening a unique window on creatures that grazed and hunted more than 30,000 years ago on this inland patch of southern California.

On maps, each end of this arid hollow has a name - the Domenigoni or Diamond Valley. But to fossil experts from the San Bernardino County Museum, the 4-1/2-mile-long basin has become known simply as the Valley of the Mastodons.

In June, the site more than lived up to its name when team member Steven Kesler spied a fossil bone poking up through the soil. Over the next three weeks, that bone would point the way to the most complete mastodon ever uncovered on the West Coast.

By the time members of the team had safely carted away the last bits of the creature, dubbed Little Stevie, preliminary measurements gave the mastodon a height of 9-1/2 feet at the shoulder. In size, Little Stevie bows only to 10-foot Max, another fossilized mastodon uncovered at the reservoir in 1995 and thought to be the largest specimen from the Western United States.

Pleistocene Park

The valley might most accurately be called Pleistocene Park, as paleontologists discover a rich mix of Ice Age plants, birds, insects, fresh-water marine life, and mammals. The mammal fossils span the food chain and include species never before reported in southern California's interior, from ancient long-horned bison and the North American lion to ground sloths and early horses.

"There are lots of late-Pleistocene assemblages all over North America," says Eric Scott, the paleontologist in charge of field operations at the reservoir. "But there aren't many with the large assemblage of species we have."

The granddaddy of them all is Los Angeles's La Brea tar pits, which trapped creatures big and small in ink-black goo. With some 4 million fossils ranging in age from 11,000 to 40,000 years and extremely well-preserved, "La Brea is the No. 1 richest locality for terrestrial Ice Age fossils anywhere on the planet," says Mr. Scott. He cut his paleontological teeth there as a volunteer when he was 16 years old, and continued working there as a professional until hired by the San Bernardino County Museum in 1990.

Yet as paleontology expands to include efforts to reconstruct ecosystems and the creatures that lived there, as well as their skeletal remains, sites like the Valley of the Mastodons are becoming increasingly important. La Brea's collection, for example, has an overabundance of meat-eaters like saber-toothed cats, which got mired as they tried to feast on the prey trapped in the tar. The collection emerging from the Valley of the Mastodons, by contrast, represents a broader rendering of the mix of Ice Age creatures at a site.

Not bad for a site where the dam project's environmental impact report held that people were unlikely to find fossils of any scientific value.

"We'll never have several million fossils" or ones that match La Brea's degree of preservation, Scott acknowledges. "But in this valley, we're finding a more accurate cross section" of the plant and animal life that shared this area.

A mammoth-sized project

The researchers' efforts here represent the largest fossil-mitigation, or salvage, effort in the United States, according to Kathleen Springer, the lead investigator on the dig. Federal, state, or local regulations require such projects to ensure that important evidence about a site's natural history isn't lost forever to pipelines, housing tracts, shopping malls, or landfills.

At the Valley of the Mastodons, she says, the goal is to record and gather as broad a sample of these ancient remains as possible before 1999, when the Metropolitan Water District (MWD) of Southern California begins pumping 269 billion gallons of water into what will be the region's largest reservoir.

Tight construction schedules and the immense bites of soil the shovels take guarantee that the vast majority of fossils will vanish or be reburied as part of three earth-fill dams.