The pebbles, also called cobbles, which can be used as gravel, as ballast or as cobblestones, are mainly milky-white quartzite but can vary in colour and composition, including some that are hard, reddish-coloured sandstone.
A notable example is Heidelberg in the German state of Baden-Württemberg, whose old town, including the Old Bridge and the castle, is built mostly from the local Odenwald sandstone.
[2] Within the parkland surrounding the castle ramparts, there is also a publicly accessible outcrop mentioned in many local nature guides, where the succession from greyish granite to reddish buntsandstein is marked clearly by an eroded gap.
[3] The architecture of the surrounding former Palatinate territory, as well as the neighbouring Rhenish Hesse, modern Palatinate, Odenwald and Alsace areas traditionally make use of the building material for representative and public buildings, among them the historically important Straßburger Münster, and the Imperial Cathedrals of Speyer, Mainz, and Worms, as well as many burgeois residences, manors and medieval castles like Trifels and the Château du Haut-Kœenigsburg.
This sandstone is widespread across central Europe, notably in the Black Forest and Odenwald region of Germany, as well as the Vosges Mountains in northeastern France.