¹⁸O PROFILE OF ICE CORE

The ¹⁸O profile was determined from 760 equally spaced samples along the length of the core. The ¹⁸O values from the upper 107.5 m of the core generally were within the +/- two sigma range of lateral variability calculated from the surficial snow grid data. From 107.5 m to 105 m, the mean ¹⁸O value shifted abruptly to -19.81 to 0.91 permil lighter than the mean core value of -18.90. Using age-to-depth relationships developed from the ³H and ¹⁴C data, this isotopically lighter section of the core corresponds to the approximate time interval from the early-to-mild 1800's A.D., thus encompassing the end of the LIA. The pronounced shift to lighter isotopic values in the section of the core corresponding to the approximate time interval of the LIA suggests that a low resolution, stable isotope record of climate has been preserved.