chap. xii. Valdivia. Conception. 397 



interested me, as being the first in which I found in 

 South America, formations perhaps of tertiary origin, 

 broken by lines of elevation. 



Valdivia: Island of Mocha. — The formations of 

 Chiloe seem to extend with nearly the same character 

 to Valdivia, and for some leagues northward of it : the 

 underlying rocks are micaceous schists, and are covered 

 up with sandstone and other sedimentary beds, including, 

 as I was assured, in many places layers of lignite. I 

 did not land on Mocha (lat. 38° 20'), but Mr. Stokes 

 brought me specimens of the gray, fine-grained, slightly 

 calcareous sandstone, precisely like that of Huafo, con- 

 taining lignite and numerous Turritellse. The island is 

 flat topped, 1,240 feet in height, and appears like an 

 outlier of the sedimentary beds on the mainland. The 

 few shells collected consist of: — 



1. Turrit ellai Chilensis, G. B. Sowerby, PI. IV. f. 51 (also at Huafo). 



2. Fusus, very imperfect, somewhat resembling F. subreilexus of 



Navidad (PI. IV. f. 57), but probably different. 



3. Venus, fragments of. 



Conception. — Sailing northward from Valdivia, the 

 coast-cliffs are seen, first to assume near the R. Tolten, 

 and thence for 150 miles northward, to be continued 

 with the same mineralogical characters, immediately to 

 be described at Concepcion. I heard in many places 

 of bed sof lignite, some of it fine and glossy, and likewise 

 of silicified wood ; near the Tolten the cliffs are low, 

 but they soon rise in height ; and the horizontal strata 

 are prolonged, with a nearly level surface, until coming 

 to a more lofty tract between points Rumena and 

 Lavapie. Here the beds have been broken up by at 

 least eight or nine parallel lines of elevation, ranging 

 E. or ENE., and W. or WSW. These lines can be 

 followed with the eye many miles into the interior ; 

 they are all uniclinal, the strata in each dipping to a 



