The detailed water isotope data consists of 2 sections of delta-18O data and 2 sections of delta-D data. The cores was drilled to bedrock 1979-1981 during the GISP program. Position: 65.18N, 43.83W, 2480 m a.s.l.. The delta-18O data were all measured immediately after the drilling (1979-81), while the delta-D data were measured in 2004 specifically for the GICC05 dating effort. The delta-18O data uncertainty is 0.1 per mil, while the delta-D data uncertainty is 0.5 per mil. All sections are cut to achieve an average resolution of 8 samples per year, i.e. the depth resolution increases with depth (as annual layer thicknesses thin). The cutting scale for the d18O data generally produced a higher resolution than intended, while the delta-D cutting scale was adjusted to be more precise in achieving 8 samples per year. All sample depths are given for the bottom of each sample.