132 bulletin: museum of comparative zoology. 



the elevation of their edges as seen from the train and the tops of such 

 terraces may rise higher than the figures above given. From Con- 

 cepcion at the seaward mouth of the gorge to San Rosendo along the 

 river is a distance of 70 kms. (42.7 miles). Taking sea-level in 

 Pleistocene time at Concepcion as forty-five feet, the San Rosendo 

 terrace gives a uniform rise up the river of 4.3 feet per mile for the 

 grade of the river, not in the least too steep to be within the range of 

 streamaction for the entire distance above Concepcion. It does not 

 appear to me therefore that the terraces of the Rio Bio Bio within 

 the Coastal Cordillera demand a lower stand of the land than is indi- 

 cated by the delta plain at Concepcion. 



The traces of a higher floor of the valley shown in the faint rock- 

 terraces within the gorge of the Bio Bio are of very ancient date. 

 They appear to be more deeply dissected than the rock-bench at 

 Corral wnth which it would be hazardous to correlate them. The 

 tops of the low hills of Tertiary rocks piercing the plain at Concepcion 

 are possibly nearer the level of the Corral bench, but these and other 

 questions concerning ancient changes of level of baselevelled rock 

 surfaces on this part of the coast of Chile await further study. I am 

 only able to state that as the result of my own observations it appears 

 that an elevation since late Pleistocene times has taken place at 

 Concepcion amounting to something like fort^-five feet; that at 

 Corral and Valdivia an older Pleistocene or late Pliocene uplift of 

 about sixty feet is indicated, and that a recent uplift of a few feet not 

 more than ten and perhaps not more than five feet is indicated, and 

 that, in conclusion, the coast of Chile affords a largely open field for 

 the determination of the changes of level which it has undergone in 

 relation to the sea during Pleistocene and late Pliocene times, involv- 

 ing a thorough revision of Darwin's studies on this subject in the light 

 of criteria which were not in his time applied to the study of shore- 

 lines. 



IX. STONE IMPLEMENTS AND POTTERY FROM 



LACUNA. 



By R. B. Dixox. 



A number of specimens from an aboriginal camp-site near Laguna, 

 Province of Santa Catharina, have been placed in my hands for 

 description, by Prof. J. B. Woodworth. The specimens comprise 

 stone implements and pottery sherds. The stone objects are of three 

 varieties, (1) hammer-stones, (2) smoothing-stones, (3) and celts. 



