106 STUDIES IN GEOLOGY, No. 4 



general considerations that demand formulation and certain 

 qualifications that are often lost sight of in discussions of 

 this sort. 



The fossil flora contains no elements of the existing flora 

 of Central Chile, but in every case its elements are represented 

 by modern species of tropical South America east of the 

 Andes, and in the main of forms dwelling in the Amazon 

 basin, especially toward the Peruvian part of the basin, and 

 extending southward into eastern Bolivia. Does this mean 

 a tropical climate in southern Chile during the Miocene cor- 

 responding to that at present in eastern Peru or around the 

 headwaters of the Rio Chapare in Bolivia, and what is a 

 tropical climate? Naturalists use these terms in a qualitative 

 rather than a quantitative sense, and generally very loosely. 

 The statement that the climate of our own western early 

 Tertiary or that of Alaska and West Greenland was tropical 

 or subtropical is hackneyed and yet it is, I believe, far from 

 the truth. 



Although the Chilean fossil forms are most like those of 

 the existing upper Amazon rain, forests, there are wanting 

 certain elements that would render such a deduction of past 

 conditions conclusive. It is true many of these elements, 

 such as epiphytes for example are not likely to take their share 

 in the fossil record, but on the other hand it is scarcely realized 

 to what an extent the flora of the tropics pushes into the 

 temperate zone or up into the mountains where environments 

 are favorable. Ficus and Cinnamomum may indicate trop- 

 ical climate or they may indicate conditions not more tropical 

 than the present climate of Georgia or Florida. Some trop- 

 ical plants undoubtedly cannot exist except in torrid low- 

 lands, but the vast majority of the forms belonging to so- 

 called tropical genera that occur in fossil floras, belong to 

 old and large genera with -a very considerable range of 

 adaptability. In the case of the Chilean fossils, although 

 their immediate existing analogues are often lowland trop- 



