Table 1: Densities and snow loads for individual levels in 1967 and 1978

The deformation of a 20 m deep firn pit in the accumulation area of Kesselwandferner was surveyed over aperiod of 11 years. Six or seven surveying markers had been installed at each of 14 levels. The survey shows tImt the shear strain rate is independent of depth and the originally circular pit cross section was changed into an ellipse. In the direction of the glacier flow, the diameter was increased, the strain rate being approximately independent of depth. Transverse to the flow, however, the diameter decreased, the strain rate becoming higher as the depth increased. The vertical strain rates responsible for thinning of firn layers decrease with depth.

(Table DR1) Argon isotope data and dating for individual >63 µm amphibole grains from Labrador Sea sediments, ODP Hole 105-647A

Variations of global and regional silicate weathering rates and paleo-ocean circulation patterns are estimated by using radiogenic isotope records, but the effects of changes in provenance are generally ignored. Here sediment provenance has been constrained through the use of Ar-Ar ages for individual detrital minerals from the Labrador Sea, which can be compared directly to the radiogenic isotope compositions from the same core material. Dramatic changes in the radiogenic isotope composition of North Atlantic Deep Water through the Quaternary Period are shown to reflect discrete changes in both sources and weathering processes accompanying Northern Hemisphere glaciation. Changes in the different radiogenic isotope systems reflect the influence of source, physical weathering, and chemical weathering, and not simply changes in the underlying weathering rate or ocean circulation patterns that are typically inferred.