woodworth: geological expedition to brazil and chile. 31 



after an encounter with ice off Cape Horn. Captain Wm. B. Oakley 

 of the Oravia informed me that after the Valparaiso earthquake of 

 1906 there had been an unusual amount of ice in the sea about the 

 southern end of South America, the ice having been dislodged from 

 glaciers by the earthc^uake, so it was believed. This report agrees 

 with the effects reported by the late Prof. R. S. Tarr arising from the 

 Alaskan earthquake of 1899, which caused much disturbance of the 

 ghiciers on the Alaskan coast and warrants the belief that at least 

 local earthcjuakes may greatly accelerate the flow of glaciers. 



December Jfth. — We entered the straits of Magellan during the 

 night. To the voyageur entering the straits from the east the high 

 barren plains on the north and the treeless low-lying plain of eastern 

 Tierra del Fuego on the south alike recall the plains of glacial Cape Cod 

 veneered with glacial drift. Between Elizabeth Island and Punta 

 Arenas there are some irregular terraces of varying height, appearing 

 more like glacial contemporaneous terraces than the horizontally 

 levelled benches cut by waves. Back of the town of Punta Arenas 

 there is a deep gully at the mouth of which lies a prominent deposit 

 forming a rounded southward slanting ridge, on the seaward slope of 

 which the town is mainly built. There is a remnant of what appears 

 to be a stream delta north of the town, now forming a terrace. The 

 Pour-quoi-pas of M. Charcot's French Antarctic expedition lay at 

 anchor off the town. 



The passage from Punta Arenas to Cape Holland was made after 

 4 P. M. but permitted a general view of the profile of the Andes 

 rising above the plains of Tierra del Fuego. (Fig. 5.) It is evident 



Fig. .5. — Generalized profile of the Andes on Tierra del Fuego. showing the 

 arcliing up of a once baselevelled but now deeply dissected mountain mass. 

 Ft is not here intended to interpret the steep western descent into the 

 Pacific Ocean. 



that here as far to the north the peaks and valleys are carved out of 

 a theoretically smoothened surface of the deformed rocks composing 

 the folded chain. It is conjectured that this now warped, once 

 baselevelled, surface passes beneath the Tertiary and Pleistocene de- 

 posits of the plains of Tierra del Fuego, forming the platform on which 

 these less ancient deposits repose. Towards the western margin of 



