WOODWORTH: GEOLOGICAL EXPEDITION TO BRAZIL AND CHILE. 117 
ture 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 
CORDILLERA. { LONGITUDINAL as 
CORDILLERA, {LONGN 
Fic. 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 quite 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 readily 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 earthquakes, 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: — 
