avoodworth: geological expedition to brazil and chile. 117 



tiire and faulting or otherwise, which must have attended this supposed 

 elevation, than to confirm or refute any conclusion as to the elevation 

 of the coast at a time so recent as that embraced within the period of 

 elevation of beaches, so well established in the Champlain or Hoche- 

 lagan marine district of northeastern North America. The following 

 notes and conclusions thus have the force of being made with a pre- 



THE ANDES. 

 \A/ COASTAL . _^5^fes^ E 



W. CORDILLERA : LONOrrUDlNAL ^-^^^'^^ t. 



Fig. 34. — Diagrammatic cross-section of southern Chile west of the Andes. 

 Based on Pissis and personal observation in the longitudinal valley and 

 Coastal Cordillera. 



conceived opinion ciuite opposite in most respects to the judgment 

 which in the sequel I was obliged to make. But the geological struc- 

 ture bearing on changes of level should be first set forth. 



The geological structure of Chile south of Valparaiso is in its broad 

 outlines readil}' grasped in such a rapid reconnaissance as I had the 

 opportunity to make. The main facts were clearly outlined by Pissis 

 (1875) from whose work and my own observations the following brief 

 introduction will serve to make clear the relations of the Coastal 

 Cordillera with its frequent earthc^uakes, and the chain of the Andes, 

 lying back from the coast. 



In south Chile for a great distance north and south there are three 

 well-defined topographic and structural zones, viz. : — the Andesian 

 folded chain with volcanic vents, the Longitudinal Valley confronting 

 the chain on the west, and the Coastal Cordillera forming the coast. 

 These three differently constituted areas are shown diagrammatically 

 in the subjoined cross-section. Fig. 34. 



The formations which enter into this section were roughly deter- 

 mined by Darwin (1891) as follows: — 



