woodworth: geological expedition to brazil and chile. 129 



The fifty-five to sixty foot bench at Corral is at that place about 

 fifty feet above the fine of the abandoned sea-caves. What the 

 attitude of this terrace is south of Corral I am unable to state. That 

 the depression of the coast continues increasingly southwards is 

 possibly indicated by the extensive fiord zone however much these 

 channels may have been over-deepened by the Pleistocene glaciers. 

 But Darwin's (1891, p. 233) account of sea-caves not now visited by 

 the waves on the island of Chiloe, though these small caves may be 

 more recent than those of Corral, shows the necessity of a resurvey of 

 this coast before assuming any uniform rate of tilting over great 

 distances. 



Fig 36.- — Sketch map of country about Concepcion, Chile. 



Terraces of the Rio Bio Bio wiikin the Coastal Cordillera. — From the 

 delta plain of the Rio Bio Bio at Concepcion there is a series of river 

 terraces Mithin the canon of the river rising in altitude to San Rosendo 

 at the border of the Longitudinal Valley. The railway from Talca- 

 huano to San Rosendo follows the river, rising at a very uniform grade 

 now on a lower terrace and again passing through cuts in the margins 

 of a higher terrace. The following notes w^ere taken on a railway 

 journey from Concepcion to San Rosendo. The ele\ations of the 



