Wednesday, August 19, 2009

Unknown X: The Back Story

We originally ran across the Unknown X source in about 1991 while working on the PGT-PG&E Pipeline Expansion Project, a multi-year 1000 mile-long natural gas pipeline project (survey and data recovery) that ran from Canada to central California. During the course of the project, over 9,000 obsidian artifacts were geochemically characterized and over 6,500 specimens came from Oregon sites. The north to south pipeline transect ran along the western edge of Newberry Volcano and we could easily monitor the changes in frequency of the different obsidian sources and how these changes were influenced by the distance to the various sources.

At this time, Richard Hughes (Geochemical Research) was analyzing all the obsidian artifacts from the Oregon sites and he recognized a new unknown source that was showing up as Newberry Volcano drew closer - Unknown X. This was a fairly early period in Oregon obsidian studies and we were running across a number of different unknown obsidian sources during the course of the project. Most of these unknowns have since been resolved by later trace element studies of Oregon obsidian sources but the Unknown X source stayed hidden. The proportion of Unknown X (and nearby McKay Butte) artifacts peaked at sites where the pipeline crossed Paulina Creek (west side of Newberry Volcano) and it seemed likely that the unknown source would be located somewhere in the same general vicinity as McKay Butte. Which, as it turns out, was exactly where it was! Hidden in plain sight.

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