EFFECTS OF LOCAL STRATIGRAPHY ON LAND SNAIL POPULATION

The land snail’s high demand for calcium carbonate directly indicates the availability of the molecule in the surrounding area. In this study, an exposed hillside in California, Pennsylvania is examined to determine the reason for an abundance of snails inhabiting the unprotected area. The multitude of living snails and the unusual abundance of remnant shells, indicate the existence of a unique source of calcium carbonate. It has been determined that the uppermost section of stratigraphy of the hillside is composed of thick limestone, suggesting that leeching of groundwater containing the dissolved calcium carbonate is providing a supply for the land snails. In this study I compared an assessment of the remnant shells to the underlying stratigraphy of the hillside to determine where and why the shells collected. Results indicate a strong correlation between the uppermost limestone section and the deposited shells below. The shells accumulate in bands that decrease in quantity as they move further downhill from the limestone. The snails’ tendency to live near the upper limestone section indicates that it is the source for their calcium carbonate consumption. This link between the geology and biology of the area under investigation can be used to further explain the relationship of land snails with limestone.