xii Contents. 



CHAPTER XIII. 



PLUTONIC AND METAMORPHIC ROCKS: — CLEAVAGE AND FOLIATION. 



Brazil, Bahia, gneiss with disjointed metamorphosed dikes — Strike 

 of foliation — Eio de Janeiro, gneiss-granite, embedded fragment 

 in, decomposition of — La Plata, metamorphic and old volcanic 

 rocks of — S. Ventana — Claystone porphyry formation of Pata- 

 gonia ; singular metamorphic rocks ; pseudo-dikes — Falkland 

 Islands, palaeozoic fossils of — Tierra del Fuego, clay-slate forma- 

 tion, cretaceous fossils of ; cleavage and foliation ; form of land — 

 Chonos Archipelago, mica schists, foliation disturbed by granitic 

 axis ; dikes — Chiloe — Concepcion, dikes, successive formation of 

 — Central and Northern Chile — Concluding remarks on cleavage 

 and foliation — Their close analogy and similar origin — Strati- 

 fication of metamorphic schists — Foliation of intrusive rocks — 

 Eelation of cleavage and foliation to the lines of tension during 

 metamorphosis page 422 



CHAPTER XIY. 



CENTRAL CHILE : — STRUCTURE OP THE CORDILLERA. 



Central Chile — Basal formations of the Cordillera — Origin of the 

 porphyritic claystone 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, 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 the 

 Puente del Inca; fossils of — Great subsidence — Intrusive por- 

 phyries — 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 470 



CHAPTER XY. 



NORTHERN CHILE. — CONCLUSION. 



Section from Illapel to Combarbala ; Gypseous formation with 

 silicified wood — Panuncillo — Coquimbo ; mines of Arqueros; 

 section up valley; fossils — Guasco, fossils of — Copiapo section 



