A publication of the Archaeological Institute of America
Letter From Hawaii
Ideal conditions within an ancient cave system are revealing a rich history that reaches back to a time before humans settled the island and extends to the present day
Some six million years ago, in the middle of the North Pacific Ocean, volcanic activity bubbling up from deep beneath the Earth’s crust formed Kauai, the most ancient of Hawaii’s major islands. Over time, volcanoes dotting the island spewed magma that cooled and turned to igneous rock, forming steep mountains. Rainwater flowed down the mountains, and, as that runoff reached the Mahaulepu Valley on the island’s southeast coast, it encountered fossilized sand dunes, where, through a process called dissolution, a network of caves was formed.
For more than 100,000 years, groundwater seeped in and eroded the limestone. Some 7,000 years ago, the sea encroached and a large portion of the ceiling of one of these caves collapsed, leaving behind a vast oval, mostly open to the sky and filled with brackish water that didn’t dry up until the middle of the twentieth century. It also created what would turn out to be a unique and fortuitous set of conditions that preserved a long, dramatic story of geological change and biological invasions, and of the waves of humans that successively altered the island in radical ways. Paleoecologists and archaeologists working there, surrounded by the high, ancient limestone walls, are beginning to read that record.
Wedged in a crease of hills just above a long white-sand beach favored by sailboarders, the sinkhole sits in a setting so picturesque that Johnny Depp’s Captain Jack Sparrow leaped off the lip of one of its high cliffs in the recent Pirates of the Caribbean movie On Stranger Tides. There, everything from a 352,000-year-old lava flow to a Styrofoam cup washed in during a recent hurricane has been preserved. For the past quarter century, husband-and-wife paleoecologists David Burney and Lida Pigott Burney, along with dozens of colleagues and volunteers, have been digging down through the black mud that fills the sinkhole. There they have uncovered millions of fossils—in fact, the site, referred to as Makauwahi Cave, may be the richest fossil site in the entire Pacific region. The upper levels contain thousands of artifacts, ranging from animal bones to stone tools and carved wood, all of which were washed, blown, or thrown into the cave. But despite the richness of the site in terms of the evidence, Burney doesn’t need expensive drilling equipment or a massive dig project to plumb the site’s secrets. “It’s the poor man’s time machine,” he says. Small trowels, a very good water pump to keep groundwater under control, and wood-framed screens, along with a great deal of tenacity, are all that’s required.
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