The ice core was drilled during the GRIP project in 1989-1992 at the Summit of the Greenland ice sheet. The length is 3025 m. Present-day accumulation 0.23 m ice/yr. Position 72.57N 37.62W, 3232 m a.s.l.. Impurities were measures as described in Fuhrer et al. (1993). The Holocene data were used for annual-layer identification during the making of the GICC05 and GIC21 time scales, but data are also provided over GS-1 (roughly equivalent to the Younger Dryas) and GI-1 (roughly equivalent to the Bølling-Allerød period). Data from deeper sections exist. Corresponding data author: Hubertus Fischer, Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, University of Bern, hubertus.fischer@unibe.ch.