Fig. 1

a - Map of Europe with location of the Winterswijk sampling site in the east of the Netherlands; b-c - Field photographs of the sampled Muschelkalk Formation limestones; d - Field photograph of the sampled red marly limestones interlayered with the Muschelkalk Formation limestones; e - Field photograph of the Rhaetian Formation claystones, which were so soft that they were sampled with plastic tubes, here sticking out of the sediments