The δD of cellulose from 14 C-dated wood, collected in the San Juan Mountains of southwestern Colorado, decreased by about 45‰ from 9600 to 3100 yr B.P. and an additional 25‰ to the present. The wood samples are from trees that grew above present-day tree line and reflect a time of warmer average summer temperatures. These changes in δD are interpreted to indicate a major change during the Holocene in the sources of moisture, in the seasonality of precipitation, or in both.
No takes yet. Share an insight, caveat, or question.
Friedman et al. (1988) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: