The limestone of the Dogger, called Limestone of the Great Oolithe, outcrops in the summit part above the vines of the Steinkesselreben of Rorschwihr not far from the German cemetery. It is a compact limestone, yellowish-white, with small rounded grains (oolites), very characteristic; We find, at several levels, spicules of sea urchins, corals, oysters, brachiopods, encrines, pentacrines, hexacoralliaries or Ammonites. This limestone formed in rough and warm waters, therefore shallow, is called oolitic limestone. These stone eggs, or aggregates of small limestone grains whose center (nucleus) is a debris (quartz grain or organism fragment), around which thin concentric limestone layers (cortices) are formed, can be called pisoliths if the spheres exceed 2 mm, which is the case here.
In the Steinkesselreben, these very typical limestones are reworked on their surface more or less deeply and the elements rolled into pebbles in the Tertiary era belong to “limestone and inter-stratified marl conglomerates” elaborated from the Priabonian to the Rupelian and partially colluviumed more or less deeply. by limestone marls with grypheus.
This geological overview is taken from a private study carried out by the INSTITUT DE GEOLOGIE DE UNIVERSITE LOUIS PASTEUR DE STRASBOURG (Claude SITTLER and Robin THIRION) at a scale of 1: 5000 on behalf of DOMAINE ROLLY-GASSMANN.