Unique amongst the Central European Uplands are the constant changes between plains, ravines, table mountains and rocky regions with undeveloped areas of forest.[3] The tremendous variety of shapes in the sandstone landscape is a result of the subsequent chemical and physical erosion and biological processes acting on the rocks formed from those sands laid down during the Cretaceous Period.Its stratification is characterized by variations in the horizontal structure (deposits of clay minerals, grain sizes of quartz, differences in the grain-cement) as well as a typical but fairly small fossil presence and variably porous strata.The most striking evidence of this phase in the earth's history are the conical basaltic hills of Růžovský vrch, Cottaer Spitzberg and Raumberg, but also Großer and Kleiner Winterberg.In 1839 Bernhard Cotta wrote about this in his comments on the geognostic map: "Vertical fissures and cracks cut through, often virtually at right angles, the horizontal layers and, as a result, parallelepiped bodies are formed, that have given rise to the description Quader Sandstone.".For example, collapse caves, small hole-like cavities (honeycomb weathering) with hourglass-shaped pillars, chimneys, crevices and mighty, rugged rock faces.Important indicators of such processes in the polygenetic and polymorphic erosion landscape of the Elbe Sandstone Mountains are the furrows with parallel ridges between them (grykes and clints) that look like cart ruts and which are particularly common, as well as extensive cave systems.[10][11][12][13][14] Czech geologists have identified in quartzite-cemented sandstone areas in the northern part of the Bohemian Cretaceous Basin, karst features in the shape of spherical caverns and cave formations.Places of interest include the Bastei cliffs near Rathen, the Königstein Fortress, Pravčická brána, the Schrammsteine, Pfaffenstein, and the valleys of the Kirnitzsch and Kamenice rivers.Visitors can experience the natural scenes on the asphalt Elbe cycle path, or on board a steam paddleboat that is part of the oldest fleet of its kind in the world.