The Snuggedy Swamp is a back-barrier estuarine depositional environment. Extensive peat deposits as much as 15 feet (450 cm) thick are underlain by kaolinite-rich clay similar to the underclay associated with coal seams. These peat and underclay deposits are underlain by silt and clay which coarsen upward and were deposited in lagoons; the peat deposits are surrounded by eroding sand areas that are the remains of Pleistocene barrier islands. At present the salt marsh is encroaching on the swamp, destroying the fresh water vegetation that forms the peat and covering the peat with clays and salts. The thickest peat deposits in this swamp are orientated parallel to the surface trends of the barriers or preexisting tidal inlets. Peat islands are hypothesized as the method by which peat was deposited in this swamp. Initially this region consisted of extensive salt marsh and probably some open water areas. Then fresh water vegetation began to colonize those areas of the salt marsh that were farthest removed from the areas of tidal creek submergence, and eventually fresh water vegetation covered the surface of the marsh. These coalescing fresh water peat islands resulted in an undulatory contact between the peat and the underclay. Two types of splay deposits are interbedded with the peat in this area, crevasse splays and fire splays. Both are composed mainly of clay, but fire splays are dintinguished by a dark fusinite (charcoal) zone at their base.