chap. vin. Elevation of Patagonia. 199 



height : this plain abuts against the foot of a higher 

 plain of 330 feet, which extends also, far northward 

 along the coast, and likewise into the interior. In the 

 distance a higher inland platform was seen, of which 

 do not know the height. In three separate places, I 

 observed the cliff of the 245-255 feet plain, fringed by 

 a terrace or narrow plain estimated at about 100 feet 

 in height. These plains are represented in the fol- 



lowing section : — 



No. 17. 

 Section of Plains at Port Desire. 



Not Measured. 



• 



cofl 



Shells 

 on sur- 

 face. 





245 to 

 255 ft. 

 Ba. M. 



Shells 

 on sur- 

 face. 







— \ 



\ 











\ 



100 ft. Est. 





N 



Level of sea. Scale ^ of inch to 100 feet vertical. 



In many places, even at the distance of three and 

 four miles from the coast, I found on the gravel-capped 

 surface of the 245-255 feet, and of the 330 feet plain, 

 shells of Mytilus MagellaniciiSj M. edulis, Patella 

 deaurita, and another Patella, too much worn to be 

 identified, but apparently similar to one found abun- 

 dantly adhering to the leaves of the kelp. These 

 species are the commonest now living on this coast. 

 The shells all appeared very old : the blue of the 

 mussels was much faded ; and only traces of colour 

 could be perceived in the Patellas, of which the outer 

 surfaces were • scaling off. They lay scattered on the 

 smooth surface of the gravel, but abounded most in 

 certain patches, especially at the heads of the smaller 

 valleys : they generally contained sand in their insides ; 

 and I presume that they have been washed by alluvial 

 action out of thin sandy layers, traces of which may 

 sometimes be seen covering the gravel. The several 



