Sinkholes in glacial drift underlain by gypsum in Nova Scotia, Canada

Abstract

Nova Scotia contains enormous deposits of Windsor Group (Mississippian) gypsum overlain by extensive late Wisconsian glacial drift. A variety of dissolution karst structures and land forms are the outstanding feature of many areas underlain by gypsum, including sinkholes. These sinkholes are typically filled with clay, sand or other materials including organic deposits of glacial origin as well as older karst fill of Cretaceous age. Adams of the Nova Scotia Department of Natural Resources reported in 1991 that “All deposits of gypsum quarried at present have innumerable karst features over their upper surfaces infilled by Pleistocene materials and annually cases of sinkholes suddenly opening up on properties around the province graphically show that dissolution of gypsum and anhydrite continues at present.” A comparison of the surficial geology map of the province with the distribution of gypsum occurrences and deposits establishes that gypsum in Nova Scotia is overlain by glacial deposits dominated by ground moraine. The purpose of this paper is to make more explicit the widespread coexistence of gypsum, glacial deposits and sinkholes in Nova Scotia.