Native artifacts off Calif. being washed away

updated 5:09 p.m. ET April 5, 2009

SAN MIGUEL ISLAND, Calif. - Perched on the edge of this wind-swept Southern California island, archaeologist Jon Erlandson watches helplessly as 6,600 years of human culture — and a good chunk of his career — is swallowed by the Pacific surf.

It was not long ago that this tip of land on the northwest coast cradling an ancient Chumash Indian village stretched out to sea. But years of storm surge and roiling waves have taken a toll. The tipping point came last year when a huge piece broke off, drowning remnants of discarded abalone, mussel and other shellfish that held clues to an ancient human diet.

"There's an enormous amount of history that's washing into the sea every year," Erlandson said matter-of-factly during a recent hike. "We literally can't keep up."

The sea has long lashed at the Channel Islands, also known as the North American Galapagos — stripping away beaches, slicing off cliff faces and nibbling at hundreds, perhaps thousands, of cultural relics.

Past coastal erosion for the most part was a natural phenomenon, but the problem is feared to grow worse with human-caused global warming and higher sea levels.

In a race against time and a rising tide, Erlandson and other keepers of history are hurrying to record and save eroding artifacts, which hold one of the earliest evidence for human seafaring in the Americas.

"We're just hoping there's something left," he said.

Around the globe, climate change is erasing the archaeological record, already under assault from development, grave robbers and illegal trade. Most at risk are prehistoric burials entombed in ice and ancient settlements hugging ever-shrinking coastlines.

A warming planet is speeding the melting of polar ice, threatening to expose frozen remains like Scythian warrior mummies in Mongolia. Thawing permafrost is causing the ground to slump on Canada's Herschel Island, damaging caskets dating to the whaling heyday. Accelerated glacial melting may flood pre-Incan temples and tombs in the northern Andean highlands of Peru.

Meanwhile, sea level rise fueled by global warming is expected to hasten the disappearance of historic coastal villages. Vulnerable places include Alaska's early Eskimo hamlets, Egypt's monuments of Alexandria and about 12,000 seaside sites in Scotland including the Neolithic settlement of Skara Brae.

'History is disintegrating'
"There are whole civilizations that we risk losing completely," said C. Brian Rose, president of the Archaeological Institute of America. "History is disintegrating before our very eyes."

The past is fast fading on the Channel Islands, a chain of eight largely undeveloped islands just off the mansion-studded Southern California coast. Though five of the islands make up the Channel Islands National Park, they are not protected from the sea's fury.

In 2005, the U.S. Geological Survey found that half of the 250 miles of shoreline studied on the Channel Islands were vulnerable to sea level rise. The most at-risk were the San Miguel and Santa Rosa coasts, home to thousands of archaeological relics from house pits to trash heaps to random scatters of stone anvils and burned rocks.

Damian Dovarganes / AP Quintan Lotah, a Chumash monitor, and archaeologist Jon Erlandson, right, check the soil for artifacts on San Miguel Island.

Deciphering the rich cultural resources on the Channel Islands may help fill in the scientific gap in the study of how humans peopled the Americas.

Scientists long theorized the first bands of Americans arrived from Asia by following big game herds over a land-bridge between Siberia and Alaska some 13,000 years ago. Once in North America, the story goes, they trekked south through the interior.

In recent years, a new thinking has emerged suggesting the first immigrants arrived by boat and followed a coastal route into the New World.

Archaeological evidence suggests Indians from the mainland plied the Santa Barbara Channel and inhabited the Channel Islands for about 13,000 years until the early 19th century. The islands are littered with one of the longest records of maritime hunter-gatherers in the Americas.

Since the beginning of time, wind and water have pounded the Channel Islands, causing bluffs to retreat and submerging native artifacts. The worst destruction tends to occur during the heavy rains of El Nino, a periodic warming of parts of the tropical Pacific Ocean.

In the past century, global sea levels crept about 7 inches higher due to warmer waters expanding and runoff from glaciers and ice sheets. Continued global warming driven by the spewing of heat-trapping greenhouse gases is expected to cause oceans to rise by about 39 inches by 2100.

During the last interglacial period about 125,000 years ago, sea level was estimated to be at least 20 feet higher. Waves carved stepped terraces on the Channel Islands. There were no humans back then — only saber-tooth cats, pygmy mammoth and other beasts — unlike the current interglacial period that started about 12,000 years ago and overlapped with the Chumash culture.

Anthropologist Jeanne Arnold of the University of California, Los Angeles, who has conducted extensive work on the Channel Islands, said archaeological sites are not a renewable resource.

"Once it's gone, there's a lot we can speculate, but we can never say for sure," she said.

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