Paleogeography and Paleoclimate

Abstract

An island extended in the Late Jurassic like a broad strip from London in the west over the Ardennes at least to the Rhenish Massif and possibly to the Bohemian Massif (Gygi 2000a, Fig. 2, adapted and simplified after Ziegler 1988, Pl. 13, and refigured here as Fig. 1.1). Sediment was then shed from the island south- and southeastward into the epicontinental, Rhodano-Swabian Basin (Fig. 2). The epicontinental basin was filled in the process in northwestern Switzerland up to close below sea level for the first time in a vast area when the Vorbourg Member was laid down. Evidence of this is stromatolites with dewatering (prism) cracks and birdseye pores which were formed in the upper intertidal zone (Figs. 4.4–4.6 and 5.8). Very large, circular and shallow footprints of sauropod dinosaurs on an ancient tidal flat in the Reuchenette Formation of Kimmeridgian age were found by the author on the upper bedding plane of bed no.17 of section RG 434 that he measured in July of 1986 in the eastern quarry of Steingrueben on the territory of the township of Oberdorf, northwest of the city of Solothurn (Gygi 2000a, Pl. 42, and Gygi 2003, p. 156). The very distinct footprints had a diameter of 0.5 and 0.7 m, respectively. Many more dinosaur footprints were found thereafter in the Reuchenette Formation, mainly in the region of Ajoie in Canton Jura.