The general aspect of the central-eastern part of the province is that of a plain gently tilted to the east that is dissected by valleys. The surface of the plain has a calcrete crust. The valleys of La Pampa, known as the transverse valleys () are NE-SW oriented, with breadths of various kilometers and lengths of tens of kilometers. Some of the valleys host very large fossil inland dunes. Formerly functioning as windfunnels for sand at present these valleys are an ecotone region between the Dry and Humid Pampas.