GEOLOGY OF THE SALINE RANGE OBSIDIAN SOURCE: IMPLICATIONS FOR SAMPLING STRATEGIES

Archaeologically significant obsidian occurs in the Saline Range, located in the northern part of Death Valley National Park in southeastern California. Most of the obsidian occurs as nodules in vitrophyres in ashflow tuff sheets. On the east side of the range, obsidian also occurs in a vitrophyre in a rhyolite intrusion that cuts across the ashflow tuff. So far, three chemically distinct types have been identified. Saline 1 and 2 occur in vitrophyres while Saline 3 occurs in the rhyolite intrusion. Obsidian bearing ashflow tuffs and related rocks, like those in the Saline Range, present problems for obsidian sourcing because 1) they occur as sheets covering large areas, 2) sheets from multiple eruptions containing chemically distinct obsidian types can be exposed in a single slope, 3) poorly welded ashflow tuff can erode easily leaving behind mixed obsidian types in secondary context, and 4)they can be emplaced over topography and faulted to create complex outcrop patterns. In order to be effective, sampling strategies must take these phenomena into account.