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STRATIGRAPHICAL GEOLOGY 
tween the positive areas. Extrusions of quartz-porphyry and 
keratophyre of Triassic age are thought to be a result of these 
movements. The distribution of these eruptive rocks serves to 
reconstruct, in their essential character, the directions of the 
Fig. 24. Structural Elements of Patagonia 
Permian movements in the southern part of Patagonia. Follow¬ 
ing the various exposures of effusive rocks the author reconstructs 
