TERTIARY FLORA OF CHILE in 



existed as mountains in earlier geologic times, although doubt 

 is thrown upon this possibility by the occurrence of Mesozoic 

 plants in the metamorphic series of the Bio Bio valley. The 

 land appears to have extended westward beyond the present 

 coast of this region during the earlier Tertiary (Eocene- 

 Oligocene) , and there is some evidence of a similar land mass 

 farther north. The latter, however, appears to have ante- 

 dated the radiation of the Angiosperms. 



The confessedly slender evidence, since it is based upon a 

 single locality in northern Peru 19 and the fossil flora in the 

 Arauco region of Chile, indicates that as late as the early 

 Miocene the flora of the Amazon Basin extended westward 

 across the present site of the Andes to the Pacific coast. 

 There apparently were no mountains high enough or contin- 

 uous enough to modify the climate as it is modified today in 

 coastal South America between Tumbez and Coquimbo. The 

 fossil flora of the Arauco region in Chile shows that an essen- 

 tially similar flora extended southward along the West 

 Coast, with some modification resulting from the higher lati- 

 tude, at least as far as latitude 40 South. 



This lower Miocene flora was essentially modern in its 

 main attributes and it would be exceedingly interesting, if 

 only sufficient evidence was available, to attempt to portray 

 the biological changes brought about by the gradual elevation 

 of the mighty Cordillera in a region of tropical, subtropical 

 and warm temperate lowland forest such as that of Mio- 

 cene Peru and Chile. 



It seems to me that it is safe to postulate, at least for later 

 Tertiary times, that the atmospheric circulation as governed 

 by the distribution of land and water and areas of high and 

 low barometric pressure, was essentially the same as it is at 

 the present time. The vast quantities of volcanic dust in the 

 Miocene and later formations of Patagonia furnish the proof, 



19 Berry, E. W., Proc. U. S. Natl. Mus., vol. 55, pp. 279-294, P ls - 

 14-17, 1919. 



