Excavation of clay slide covering buried longhouses, 1970.

The two extremes of archaeological sites are wet and extremely dry, says archaeologist Richard Daugherty. “That’s where you get your preservation—and in  between it all goes to hell.” He laughs, but that’s about the gist of it.

Wet-site archaeology potentially offers the best preservation, as was the case with Ozette and other sites on the Olympic Peninsula, such as another WSU excavation at Hoh River, and the ongoing excavation at Squaxin Island, near Olympia. But wet-site excavation is very expensive, requiring special techniques both for excavation and preservation.

At Ozette, the mudslide that buried the longhouses also preserved them because of the resulting oxygen-free conditions. Many of the artifacts recovered from Ozette are much the same as they were when they were  buried. Once they’re exposed to oxygen, however, they begin to get brittle and disintegrate. So everything that came out of the excavation immediately went into a preservative bath of polyethylene glycol. The chemical forces the water out of the artifact and solidifies it.

Getting the delicate artifacts out of the slide in the first place provided the initial challenge. Most of the wet site was excavated hydraulically. The Ozette archaeologists pumped seawater at various pressures for different stages of excavation. Initial clearing was with high pressure. Once artifacts started to show, lower-pressure garden hoses were used to clean and remove the artifacts.

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