Summary
An ice core, drilled near the margin of the Law Dome ice cap at Cape Folger, has been analysed for trace chemical content. The concentration of the major anions and cations has been measured on samples selected from the ice core to give information on the major environmental changes which have occurred in the period 7-25 ka BP. An age scale for the ice core has been estimated by comparing the chemical content and oxygen isotope records with those from the Dome C core, identifying features common to both cores and setting the age in the Law Dome core to that given for the Dome C core. A number of approximate age horizons in the core are set in this fashion, and intermediate ages found by interpolation and reference to a modeled age-depth relation. The chemical species are divided into two fractions representing the two major sources of trace chemicals: marine and continental sources. There are obvious differences between the records representing the marine and continental fractions. For the marine fraction, there are is a clear trend of decreasing concentration with depth, consistent with the ice at greater depth having an origin at higher elevation further inland on the ice cap, attaining very low concentrations in the lower part of the core. For the continental fraction, the pattern is similar to that for Dome C, very low concentrations during the Holocene and relatively high concentrations during the LGM. The concentrations of both the marine and continental fractions during the LGM are much lower than at Dome C as a result of dilution caused by the higher precipitation and snow accumulation rates near the coast. The transition from the LGM to Holocene occurs at about 80% of the ice thickness. The general trend of decreasing concentration with depth of the marine fraction is modulated by variations in the background atmospheric loading, and the effect of variations in past ice sheet and sea ice extent and thus distance to the source. For