The obsidian cobbles are easily detached from their parent rock by water erosion and carried downstream.
Earlier work using obsidian hydration dating is now questioned on methodological grounds.
The inclusion of more information on the other techniques that are applicable to obsidian studies would have been very useful.
In other words, as the rate of import increases, the proportion of the obsidian assemblage that is green decreases.
Table 3 shows the quantities of transparent green obsidian versus graystriated, clear gray, and black obsidian found at each of the three frontier sites.
All components of the rock, except the obsidian cobbles, are susceptible to weathering and are easily transformed into clay, as the matrix is quite porous.
Most households had fewer than one piece of obsidian per square meter, but a few had much higher concentrations.
Aspects of social organization are addressed through the obsidian data, as are some insights into tool production and by whom.
