Portulaca Point

PD = provenience designation; FS = field specimen; PL = point-location number.

Date symbol explanations (from the Laboratory of Tree-Ring Research, Tucson, Arizona):

• B Bark is present.
• r Less than a full section is present, but the outermost ring is continuous around the available circumference.
• v A subjective judgment that, although there is no direct evidence of the true outside on the sample, the date is within a very few years of being a cutting date.
• vv There is no way of estimating how far the last ring is from the true outside; many rings may be lost.
• + One or a few rings may be missing near the outside whose presence or absence cannot be determined, because the series does not extend far enough to provide adequate cross dating.
• ++ A ring count is necessary beyond a certain point in the series because cross dating ceases.