Sources:

Basgall, Mark E.
1990   Hydration Dating of Coso Obsidian: Problems and Prospects. Paper presented at the 14th annual meeting of the Society for California Archaeology, Foster City.

King, Jerome
2004   Re-Examining Coso Obsidian Hydration Rates. Proceedings of the Society for California Archaeology 14:135-142.

Rogers, Alexander K.
2009   An Estimate of Coso Obsidian Hydration Rate, Based on Obsidian-Radiocarbon Pairings and the "Weighted Total Least Squares" Method. International Association of Obsidian Studies Bulletin 14:9-20.


The three Coso obsidian hydration calibrations have been proposed by Basgall (upper), King (middle), and Rogers (lower): "x" is the thickness of the hydration rind, in microns; these readings are shown as vertical lines in 0.5-micron intervals in the timelines. In the Basgall and King timelines, "t" is the age in radiocarbon years before A.D. 1950; radiocarbon years have been converted to calendar years A.D./B.C., based on informally estimated means of the one-sigma intercept ranges according to Calib 6.0. In the Rogers timeline, "t" is the age in calendar years; in the timeline, these are shown as calendar years before A.D. 2000.

The calibrations do not include adjustments for temperature history, which may substantially affect the results. They also do not take into account other possibly significant factors such as humidity or intra-source chemical variability.