the extreme south of Africa we find a Permian folded mountain range striking from east to west (the Zwarte Berge). In the reconstruction the westward extension of this range strikes the district south of Buenos Aires, where the map shows nothing remarkable. Now it is an extremely interesting fact that Keidel has discovered in the sierras of this area, especially the more strongly folded southern portion, ancient folds, which from the structure, the succession of rocks and the fossil contents, are not merely absolutely similar to the Pre-Cordilleras on the north-west in the provinces of San Juan and Mendoza, which immediately adjoin the Andean folding, but above all also to the Cape Mountains of South Africa. “In the Sierras of the Province of Buenos Aires, especially in the southern ranges, we find a succession of strata which is very similar to that in the Cape Mountains of South Africa. Good agreement appears to exist in at least three beds: the lower sandstone of the Lower Devonian transgression, the fossiliferous shales which show the maximum of its extension, and a more recent, very characteristic formation, the glacial conglomerate of the Upper Palæozoic. The deposits of the Devonian transgression, as well as the glacial conglomerate, are greatly folded, as in the Cape Mountains, and the movement here, as there, is directed towards the north.”[1] From this the existence is proved of a lengthy ancient fold which cuts the southern point of Africa and then passes
- ↑ H. Keidel, Über das Alter, die Verbreitung und die gegenseitigen Beziehungen der verschiedenen tektonischen Strukturen in der argentinischen Gebirgen. Étude faite à la XIIe Session du Congrès géologique international, reproduite du Compte-Rendu, pp. 671–687 (separate, n.d.). See also a detailed account by the same author: J. Keidel, La Geología de las Sierras de la Provincia de Buenos Aires y sus Relaciones con las Montañas de Sud Africa y los Andes. Annales del Ministerio de Agricultura de la Nación, Sección Geología, Mineralogía y Minería, Tomo XI, Núm. 3, Buenos Aires, 1916.
