“…Since the implication of the presence of hydration in obsidian (Ross and Smith, 1955) and the new dating method in using observed hydration rinds introduced into archaeology in 1960 (Friedman and Smith, 1960), over the last five decades, OHD has been popularized to furnish the dates for prehistoric sites and assemblages. Obsidian artifacts both in buried and surface contexts have been used in regions where obsidian artifacts are ubiquitously found, notably in southern Pacific coast of North America (e.g., Bettinger, 1980;Hull, 2001;Meighan, 1983;Origer, 1989;Rogers and Yohe, 2011), Great Basin (Jones and Beck, 1990;Jones et al, 2003), American Southwest (Findlow et al, 1975;Ridings, 1996), East Africa (Ambrose, 2012;Michels et al, 1983), Mesoamerica (Braswell, 1992;Freter, 1993;Riciputi et al, 2002;Webster and Freter, 1990), coastal Peru (Eerkens et al, 2008), central Andes (Tripcevich et al, 2012), Oceania (Ambrose, 1994;Clark et al, 1997), interior Alaska (Clark, 1984), and Japan Kondo, 1965, 1976;Suzuki, 1971). The major reasons why OHD is accepted by archaeologists are: (1) relative easiness in the procedure of observations, measures, and calculations of dates, (2) specimens can be coupled with temporally sensitive techno-typological units such as projectile points (e.g., Jones and Beck, 1990), (3) while analysts can accommodate a large number of specimens for dates, the cost to obtain dates is not expensive (lower than the radiometric dates such as radiocarbon dating), and (4) depending on the effective hydration temperature, the applicable range of dating is deep enough to cover from the Middle Pleistocene (780,000 BP) to historic period (Friedman and Smith, 1960;Michels and Tsong, 1980;Origer, 1989).…”