Seasonal Frost Heave and Frost Penetration Measurements in the Indian Peaks Region of the Colorado Front Range

Measurements of seasonal frost heave and frost penetration were conducted on frost boils occupying the tread of a windswept, snowfree, turf-banked lobe just above tree line in the Colorado Front Range. Heave magnitudes of up to 30 cm were recorded on frost boil centers. Values were lower on intervening vegetated areas. Temporal variations in surface heave and subsidence are also described. Frost penetration rates reached 2.3 cm day-1 in the first week of the seasonal freeze-back to the permafrost table at a depth of approximately 2 m. The mean rate for the first 4 months was 1.4 cm day-1. Thaw began in mid-May and proceeded at a mean rate of 1.6 cm day-1 into August. Frost penetration was found to be strongly related to the freezing index. However, care is required in interpreting relationships established from cumulative data. Rates of frost heave were correlated in a weak but positive manner with rates of frost penetration.