ABSTRACT
Central Chile – Basal formations of the Cordillera – Origin of the porphyritic clay-stone conglomerate – Andesite – Volcanic rocks – Section of the Cordillera by the Peuquenes or Portillo Pass – Great gypseous formation – Peuquenes line; thickness of strata, fossils of – Portillo line, conglomerate, orthitic granite, mica-schist, and volcanic rocks of – Concluding remarks on the denudation and elevation of the Portillo line – Section by the Cumbre or Uspallata Pass – Porphyries – Gypseous strata – Section near Puente del Inca; fossils of – Great subsidence – Intrusive porphyries – Plain of Uspallata – Section of the Uspallata chain – Structure and nature of the strata – Silicified vertical trees – Great subsidence – Granitic rocks of axis – Concluding remarks on the Uspallata range; origin subsequent to that of the main Cordillera; two periods of subsidence; comparison with the Portillo chain.
