1835.] Estramadur a and the North of Andalusia. 355 



4. The coal basins were not all originally concentrated 

 in the Sierra Morena, where we find the present traces of 

 them ; but the deposits which were situated on the Guadiana 

 have disappeared under the influence of the same causes, 

 which have been already noticed as having wasted the 

 surface of the land. 



5. The tertiary basin of Badajoz reposing immediately 

 upon the transition formation, it follows that the fresh 

 water limestone appearing to occupy the inferior part of this 

 formation was deposited in a basin which did not exist 

 before the tertiary period. This affords proof of the occur- 

 rence of movements of the land at an earlier period, in 

 addition to the vertical position of the marls and fresh water 

 limestone of Badajoz. The characters of the euphotide and 

 diorite, and their interstratification with the dolomite, 

 shew that there is an intimate relation between the most 

 recent revolution of the land in Estramadura, and the 

 appearance of these crystallized masses. This connexion is 

 similar to that which Dufrenoy has noticed between the 

 revolutions of the third tertiary era on the two declivi- 

 ties of the Pyrenees, and the eruption of these crystalline 

 rocks, composed of felspar and actinote, which he has 

 termed ophites. That this relation does actually exist 

 between the transported formation of Castile and Estrama- 

 dura, and the third tertiary epoch of' the south of France, 

 is further proved by the circumstance that arragonite occurs 

 in both places. The crystals observed in collections come 

 principally from Molida d'Aragon and Mingranilla, near 

 Cuenca. 



With regard to the direction of the chains and stratified 

 rocks, Le Play considers that the first revolution which 

 took place between the two transition periods, produced in 

 the ancient transition strata, a rupture from east 40° north 

 to west 40° south, a direction corresponding with the slate 

 in the hills of Westmoreland, Hundsriick, &c. 



This elevation is exhibited in a regular manner in the 

 Almaden chain, and directs the course of the rivers. 



The modern transition formation was elevated at the 

 same period with that of Britain and Normandy. The 

 mechanical action which produced this elevation appears to 

 have exercised its chief force in a line passing through the 



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