A 160 m ice core was recovered in June 1996 from Eclipse Icefield (60.51 degrees N, 139.47 degrees W, 3017 m elevation).

Visible stratigraphy (location and thickness of ice layers) and density measurements were made in the field, and then the core was shipped frozen

to the University of New Hampshire. The core was continuously sampled in 10 cm segments, corresponding to a minimum of 12 samples per year.

Above the firn-ice transition which occurs at 45 m depth, core was scraped on an acrylic lathe system under a laminar flow bench using a titanium scraper so that all surface and sub-surface contamination from the drilling process was removed. Below the firn-ice transition, samples were cut into 3 x 3 cm pieces 10 cm long and the middle of the samples melted out using a custom made melter also used to sample the GISP2 ice core.

Samples were analyzed for major ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-) using a Dionex model 2010 ion chromatograph in a dedicated laboratory at the University of New Hampshire. The cation system used a CS12A column with CSRS-ultra suppressor in auto suppression recycle mode with 20 mM MSA eluent. The anion system used an AS11 column with an ASRS-ultra suppressor in auto suppression recycle mode with 6 mM NaOH eluent. Analytical precision was monitored by analyzing 10% of the samples in duplicate and found to be 11% for K+, 10% for NH4+, 7% for Na+, and less than 5% for all other species. Aliquots of the same samples were also analyzed for oxygen isotopes (delta 18O) at the Stable Isotope Laboratory in Copenhagen, Denmark (precision ± 0.05‰).

Chronology of the Eclipse ice core is based on multi-parameter annual layer counting of seasonal oscillations in the stable isotope and major ion records

(especially Na+ and NH4+). Age control on the chronology established via annual layer counting is provided by the 1963 and 1961 beta activity reference horizons and volcanic reference horizons identified by statistical analysis of the sulfate record and verified by tephrochronology. The resulting time scale indicates that the

Eclipse 1996 ice core covers the period 1894 to 1996, with dating error in the core estimated to be +1 year based on the number of independently dated horizons. The chemical data presented here are at sub-annual resolution, and annually averaged. Data for the years 1894, 1995, and 1996 are incomplete and not included in the annual averages.