THE ORIGINS AND LANDSCAPE CONDITIONS ASSOCIATED WITH VERNAL POOLS ALONG SHALE SADDLES IN THE CENTRAL APPALACHIAN MOUNTAINS OF PENNSYLVANIA

In the Appalachian Mountain Section of the Pennsylvania Ridge and Valley Physiographic province vernal pool wetlands are abundant among the headwaters. Throughout the region they are found along shale saddles - gently sloped areas between the origins of two adjacent first order streams and parallel running sandstone ridgelines. These wetlands are small, disconnected from stream networks, and exhibit ephemeral hydrology cycling between wet and dry phases often at the seasonal scale. The unique conditions associated with vernal pools make them an essential habitat for amphibian reproduction, allow for the storage of carbon for millennia, provide enhanced nutrient cycling, among many other ecological functions. To conserve these wetlands, it is imperative to be able to predict them in the landscape and understand their origins. Our work used a large data GIS approach and a Classification and Regression Tree statistical analysis in assessing saddle geomorphological metrics to determine what landscape factors are most associated with vernal pool occurrence. Additionally, carbon was collected from 30 vernal pools along a latitudinal transect for age dating with most samples found to be older than 10 kya. Soil stratigraphy was also assessed at several sites to compare the development of sediment horizons within the wetlands and nearby terrestrial areas. Two types of wetland basins were found within saddles which were likely caused by different periglacial processes. The first being an ice mound that blocked colluvial deposition, which created a depression upon thawing. Second type were found along solifluction lobes, which is a feature created by mass wasting from freeze-thaw along a slope forming a downslope berm and an upslope depression. The impacts of the last periglacial climate are profound within this region, and its role in the development of wetlands is just now being understood.