BEDROCK FREEZE-THAW WEATHERING REGIME IN AN ALPINE ENVIRONMENT, COLORADO FRONT RANGE

Reduced major axis analysis is used to describe monthly temperature averages for daily maxima, minima, means and ranges at a sequence of bedrock microenvironments. 7 thermistors buried at 1cm in bedrock provide comparative data on 3 aspects, and also upon the impact of snow accumulation against an E-facing rock wall. Intersite temperatures commonly differ by less than 5oC and, rarely, by more than 10oC. The freezing intensity of freeze-thaw cycles occurring within the confines of a seasonal snow patch rarely dropped to -5oC, while at snowfree, vertical faces, freezing dropped to -5oC quite commonly. Comparison with laboratory established criteria for effective freeze-thaw weathering suggests that moisture-rich microsites lack adequate freezing intensity, while adequately frozen sites lack moisture. Available data suggest that the overlap between freeze-thaw and hydration weathering requires careful re-evaluation.-Author