HOW MOUNTAINS BREATHE: CAVE METEOROLOGY IN THE VALLEY & RIDGE AND APPALACHIAN PLATEAU PROVINCES

Far southwestern Virginia (SWVA) lies within both the Valley and Ridge (V&R) and the Appalachian Plateaus (AP) physiographic provinces. More than 1700 caves are documented in V&R Paleozoic (Cambrian through Mississippian) limestones and dolostones. The AP of SWVA is not known for caves but contains some karst and pseudokarst features that include shelter caves and collapse caves in Pennsylvanian clastic rocks. The focus of this study is to expand basic research on cave meteorology, which is lacking in SWVA, by comparing meteorological characterizations of caves from across the region.

Cave meteorology is the study of the dynamics, properties, and microclimates of cave atmospheres. Insulation by surrounding bedrock generally suppresses cave temperature variations to around local average surface temperatures. Alternatively, air movement in caves can be significant and are driven by daily and seasonal inflows of cool, dense air and air pressure gradients across passages. Site-specific factors that influence cave meteorology include cave setting and morphology, depth, number of entrances, water, and the presence of skylights and fractures. Through these interconnections, caves serve as breathing mechanisms for mountains and produce daily and seasonal patterns of meteorological behavior that are not well recognized in ecosystem science.

We selected three very different sites for comparing aspects of cave meteorology in far SWVA: Baker Cave (elev. ~1630 ft/497 m amsl) is an undocumented sandstone cave in the AP of Dickenson County; Parsons Cave (elev. ~ 2340 ft/713 m amsl) is in gently inclined massive limestones of the Mississippian Greenbriar formation (Wise County); and Unthanks Cave (elev.~1300 ft/396 m amsl) formed in V&R Ordovician carbonates (Lee County). Each cave is instrumented with temperature, humidity, and barometric pressure data loggers, and cave surveys are being conducted to characterize cave features and dimensions. Radon and carbon dioxide testing, as well as measurements of air flow under various conditions will be completed. This research enables a more comprehensive understanding of cave meteorology and helps highlight the sensitivity of cave atmospheres to climate change.