Ice flow-unit influence on glacier structure, debris entrainment and transport.

ABSTRACT The links between structural glaciology, glacial debris entrainment and transport have been established in a number of different glacier settings. Here we document the structural evolution of a temperate Alpine valley glacier (Vadrec del Forno, Switzerland) and demonstrate that individual flow units within the glacier have very different structural and debris characteristics. The glacier consists of a broad accumulation area with multiple basins feeding a relatively narrow tongue and is formed from six distinct flow units. Each flow unit has its own characteristic structural assemblage. Flow units that narrow rapidly down-glacier are dominated by primary stratification that has evolved into longitudinal foliation. In contrast, wider flow units preferentially develop an axial planar foliation. Glacier structure plays a limited role in the entrainment of debris, which is more strongly influenced by ice-marginal rockfall and avalanche inputs onto the glacier surface. However, once entrained, glacier structure controls the reorientation and redistribution of debris within the ice mass. By taking a whole-glacier approach to describing glacier structure and debris transport, we conclude that individual flow units are unique with regard to structure and debris transfer. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]