During the past ten years excavations have been conducted at a number of archaeological sites along the Snake River between Meiba and King Hill, Idaho. Though the majority of point types from these sites are typologically of Late Archaic age (2000-150 BP) few have produced little datable organic material, though all have produced obsidian artifacts and debitage. In some instances projectile points of what are typologically Early and Middle Archaic age have been recovered. This report discusses the results of obsidian hydration analysis of 32 specimens from six sites between Walters Ferry and King Hill, Idaho. The purpose of the study was to establish Chronometrie ages for undated sites and determine if contexts that have produced temporally mixed types actually reflect distinct temporal occupations.