The Palaeozoic Belts prior to the opening of the Atlantic: according to a) Michel Faure (2013); b) Boris Choubert (1935). Note the very similar structural situation of the Hercynian belt (slate gray in the left, red on the right) as being in both sketches compressed in between Baltica-Laurentia on the one hand and Gondwana on the other hand. Fig. 2b: Deep blue: Precambrian belts; deep brown: unfolded Precambrian units; light brown: unfolded Palaeozoic units; violine: Permian rocks; yellow: post-Hercynian unfolded rocks; green: Caledonian and Taconic Belts; striped (green and red): Acadian belt; red: Hercynian belt. Thick black dashed lines: supposed outlines of the Precambrian continental blocks.