The majority of the watershed's topsoil is composed of sand, clay, and silt, under which normally lies a layer of ablation moraines. Fairly rich soils made of alluvium and tidal deposits are found along the Petitcodiac and Memramcook rivers, and have often been exploited for agricultural purposes. A publication by the New Brunswick Department of Natural Resources notes that the soils in Salisbury, made from calcareous sandstone and mudstone, are fine-textured and, when properly drained, "are the most fertile glacial tills" in the watershed. In contrast, they note, soils deriving from local conglomerates are more coarse and sandy, and are less fertile.