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 line 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. 
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PP 1] 
Fie 36.— Sketch map of country about Concepcion, Chile. 
Terraces of the Rio Bio Bio within the Coastal Cordillera.— From the 
delta plain of the Rio Bio Bio at Concepcion there is a series of river 
terraces within the cafion 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 were taken on a railway 
journey from Concepcion to San Rosendo. The elevations of the 
