The sands are underlain by calcareous hardpan. Areas between escarpments are underlain by shales. The western part comprises Torridonian sandstone underlain by Lewisian gneiss. Soils underlain by loess tend to be excessively drained. The ecoregion is mountainous, forested, and underlain by Pennsylvanian sandstone, shale, and siltstone. The area is underlain by Cretaceous sediments. Tablelands are often topped with argillite gravel and weathered quartzite, occasionally underlain by shale. Kansas is underlain by a sequence of horizontal to gently westward dipping sedimentary rocks. These valleys are underlain by limestone or dolomite. The Central Lowlands is largely underlain by Paleozoic formations. The river valleys are underlain by limestone. Waved maritime heath grows over shallow podzolic soils which are underlain by Hercynian granite. It is mostly underlain by volcanic ash, rhyolite, and tuffaceous rocks. The Inner Coastal Plain province consists of lowlands and rolling hills underlain by Cretaceous deposits. Historically, this loess belt has underlain some of Germany's richest agricultural regions.