Etching of Hornblende Grains in Arctic Soils: An Indicator of Relative Age and Paleoclimate

Abstract

The degree of etching of hornblende grains in soils is defined as the mean depth of maximum etching on 100 grains per sample and is a function of: (1) the depth in the profile; (2) the age of the deposit on which the soil is formed; and (3) the climate since deposition. In soils formed on moraines in the eastern Canadian Arctic, etching decreases logarithmically with increasing depth in the profile, and the rate of etching at a given depth decreases logarithmically with increasing age. The most important climatic parameter with respect to etching appears to be the effective precipitation. Equally important in terms of soil moisture regimen is the presence of unfrozen water. Both affect the rate of etching as a function of depth and age. The inferred climate of northern Cumberland Peninsula, Baffin Island, N.W.T., Canada, preceding, during, and following the last (Foxe) glaciation, is indicated by the degree of etching of hornblende grains in soil profiles of various ages as follows: pre-Foxe—warm/wet; early to middle Foxe—mild/moist; middle to late Foxe—cold/arid; Hypsithermal—mild/moist; Neoglacial—cool/dry.