Abstract

The volumetric expansion of freezing pore water is widely assumed to be a major cause of rock fracture in cold humid regions. Data from experiments simulating natural freezing regimes indicate that bedrock fracture results instead from ice segregation. Fracture depth and timing are also numerically simulated by coupling heat and mass transfer with a fracture model. The depth and geometry of fractures match those in Arctic permafrost and ice-age weathering profiles. This agreement supports a conceptual model in which ice segregation in near-surface permafrost leads progressively to rock fracture and heave, whereas permafrost degradation leads episodically to melt of segregated ice and rock settlement. The fracture of bedrock is fundamental todebris production and landscape develop-ment. Rock fracture in polar and alpine regions has often been attributed to the freezing and volumetric expansion of water trapped within pores and cracks (1). An alternative process of bedrock fracture, involving ice segregation, remains poorly characterized despite a number of theoretical and experimental studies over the past