Permafrost creep and rock glacier dynamics

TLDR

The review surveys thermal conditions, composition, and rheology of perennially frozen slopes, highlighting the need to integrate rock weathering, snow avalanches, freezing processes, and coupled thermohydro‑mechanical dynamics to understand permafrost creep and rock glacier behavior. The paper compiles existing data on permafrost creep and rock glaciers to aid research on subsurface ice flow and surface expressions on Earth and Mars. It synthesizes quantitative observations from drilling, borehole surveys, geophysical soundings, photogrammetry, and laboratory experiments. © 2006 John Wiley & Sons, Ltd.

Abstract

This review paper examines thermal conditions (active layer and permafrost), internal composition (rock and ice components), kinematics and rheology of creeping perennially frozen slopes in cold mountain areas. The aim is to assemble current information about creep in permafrost and rock glaciers from diverse published sources into a single paper that will be useful in studies of the flow and deformation of subsurface ice and their surface manifestations not only on Earth, but also on Mars. Emphasis is placed on quantitative information from drilling, borehole measurements, geophysical soundings, photogrammetry, laboratory experiments, etc. It is evident that quantitative holistic treatment of permafrost creep and rock glaciers requires consideration of: (a) rock weathering, snow avalanches and rockfall, with grain-size sorting on scree slopes; (b) freezing processes and ice formation in scree at sub-zero temperatures containing abundant fine material as well as coarse-grained blocks; (c) coupled thermohydro-mechanical aspects of creep and failure processes in frozen rock debris; (d) kinematics of non-isotropic, heterogeneous and layered, ice-rich permafrost on slopes with long transport paths for coarse surface material from the headwall to the front and, in some cases, subsequent re-incorporation into an advancing rock glacier causing corresponding age inversion at depth; and (e) the dynamics of rock glaciers, which include spatial and temporal variations in velocity that are manifested in the ridges, furrows and other surface structures typical of rock glaciers, as well as their down-valley motion. Copyright © 2006 John Wiley & Sons, Ltd.