| Summary: | One-sentence summary: In this report, submitted directly from the EPICA (European Project for Ice Coring in Antarctica) drilling camp in Dronning Maud Land (DML), Antarctica, we describe the microstructure of deep layers of soft ice in the EPICA-DML ice core. Abstract: A peculiarity of the EPICA-DML drilling camp in Antarctica has been the establishment of a subterranean laboratory for ice microscopy on site. There we performed the first microscopic observations of soft ice strata in the EPICA-DML deep ice core. Contrary to common expectations, the softening is not produced by preferred orientations of the ice lattice (fabric), but rather by dynamic grain boundary structures formed by microshear under conditions of high temperature, moderate stress, small grain size and high impurity content. Evidently, the existence of layers of soft ice has serious implications for ice core dating and related paleoclimatic studies.
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