More recently, major excavations were conducted under the direction of the author at Last Supper Cave (NV-HU-102), located 32 km. northeast of Hanging Rock Shelter. As a consequence of these investigations, a 9,000-year obsidian hydration sequence is now available for the site. Among the objectives of this paper is a comparative evaluation of the hydration records from Hanging Rock Shelter and Last Supper Cave. Given advances since 1972 in the measurement of obsidian hydration bands, additional hydration measurements have been obtained for certain of the specimens from Hanging Rock Shelter. Hydration data from both sites collectively support the recognition of terminal Anathermal/early Altithermal and late Medithermal episodes of occupational hiatus and projectile point stylistic discontinuity in northwestern Nevada.