THERMAL REGIME OF THE TROUGH CREEK ICE MINE, HUNTINGDON COUNTY, PENNSYLVANIA

The Trough Creek Ice Mine is a small talus cave that lies at the base of a steep slope of Mississippian Pocono sandstone and conglomerate boulders frost-wedged from the crest of Terrace Mountain, located in the Ridge and Valley province of central Pennsylvania. The ice mine is a geologic feature in Trough Creek State Park and it attracts thousands of visitors per year, who come to experience the unusual cold temperatures found there throughout the summer. As in similar “cold trap” environments in the northeastern United States, the mine accumulates ice in late winter and spring, and this ice typically persists into the early summer. Historically, the talus cave is believed to have been discovered prior to 1913 during the construction of the 15-mile-long Juniata and Southern Railroad, although it has also been described as an exploratory adit developed in the search for iron ore to supply the nearby Paradise Furnace. In this study, we placed temperature data loggers within the ice mine and on the talus slope to monitor seasonal temperature trends and variations. Loggers recorded temperature every 15 minutes over a two-year period. Air temperatures in the ice mine never exceeded ca. 4 deg C during the study period. Seasonal temperature trends demonstrated that the mine cooled rapidly during the coldest days of the late autumn and winter, as dense cold air settled into it, followed by rapid warming through conduction of heat from surrounding rock, prior to the next cold air event. When seasonal air temperatures became warmer than the ambient temperature in the mine, the mine acted as a cold air trap, and very slowly warmed over the spring, summer and autumn until cold weather reappeared. The observed temperature trends relate to the possible influence of global warming trends on the role of the cold trap as a habitat for psychrophilic bacteria, regionally endangered Allegheny wood rats, and vegetation more typical of more northerly boreal climates.