. Bulletin of the British Museum (Natural History), Geology. 178 S. WILLEFERT Carboniferous |«uj Folded chains (caledono-hercynian kyX'i Siluro-Devonian. Fig. 1 Geological sketch of the western margin of the Taoudeni Basin, Mauritania, after Deynoux (1980). Elsewhere, the surface of the sandstones at the contact with the shales is sometimes covered by a yellow coating. At Gara Foug Gara there is 2 m between 'Camarotoechia and Demirastrites triangulatus. There is therefore not much hope of defining the boundary exactly in Zemmour Noir, unless new discoveries are made in the western tectonizcd p


. Bulletin of the British Museum (Natural History), Geology. 178 S. WILLEFERT Carboniferous |«uj Folded chains (caledono-hercynian kyX'i Siluro-Devonian. Fig. 1 Geological sketch of the western margin of the Taoudeni Basin, Mauritania, after Deynoux (1980). Elsewhere, the surface of the sandstones at the contact with the shales is sometimes covered by a yellow coating. At Gara Foug Gara there is 2 m between 'Camarotoechia and Demirastrites triangulatus. There is therefore not much hope of defining the boundary exactly in Zemmour Noir, unless new discoveries are made in the western tectonizcd part. The Silurian has been noted in the Dhlou Chain but has not been systematically studied. 2 The Mauritanian Adrar (Fig. 2B, but chiefly Deynoux et al. 1985: 371, fig. 11; 374, fig. 12; 378, table 3). This area geomorphologically consists of (roughly from NNE to SSW), the Atar plain, the cliff, the plateaus (tabular zone) and the SW margin (folded zone), overlapped by the Mauritanides chain. The Ordovician-Silurian boundary is exposed in the two last units, but the area can be treated as a whole, whilst noting that the Silurian becomes more sandy to the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)


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