GEOLOGICAL CHARACTERISTICS
On a northern third of this locality, the subsoil is made up of gray or variegated marls of the lower keuper more or less silty and dolomitic. In these lands, deposits of marine lagoons, with evaporites, there are beds of anhydrite or gypsum (formerly exploited in Riquewihr in Schoenenbourg, in Bergheim in Kanzlerberg and, in part, in Haguenau in Bergheim as well as in Lachreben in Rorschwihr.). However, these lands do not really level, because it is a faulty compartment, at the foot of the Vosges fault, covered by fine scree and sandy colluvium from both conglomerates and sandstones of the Vosges and granite arenas. . The southern and main part of the locality is made up of the marls and limestones of the Lias (Sinemurian and Pliensbachien) as at the Silberbergof Rorschwihr located 60 to 80 meters higher in another tectonic compartment. Topographically, the Grypheus marls and limestones of the lower Lias, which are located upstream, to the west, while the clays and marls with ferruginous ovoids with calcareous sandstone of the Middle Lias, are located below, to the east. A NW-SE direction fault therefore separates the two floors of the Lias.
This geological overview is taken from a private study carried out by the INSTITUT DE GEOLOGIE DE L’UNIVERSITE LOUIS PASTEUR DE STRASBOURG (Claude SITTLER and Robin THIRION) at a scale of 1/5000 on behalf of DOMAINE ROLLY-GASSMANN.