ANTARCTIC GEOLOGY AND POLAR CLIMATES. 



By WILLIAM MORRIS DAVIS. 



(Read April 22, iqio.) 



It seems desirable at the present time of active interest in 

 Antarctic exploration to call attention to a point that deserves the 

 special scrutiny of geologists who may visit far southern regions. 



Exploration already accomplished has shown that the Antarctic 

 as well as the Arctic lands contain geological formations indicative 

 of a much milder climate than that which prevails in high latitudes 

 today. Thus far, the evidence of mild polar climates has been 

 drawn almost exclusively from fossils or land plants contained in 

 stratified continental deposits. The structure of non-fossiliferous 

 continental formations at high latitudes has not been minutely 

 studied in their bearing on climatic problems. Investigations of 

 recent years in temperate latitudes have however shown that the 

 detailed structures of land-laid stratified deposits may also be used 

 with much success in determining the climate under which they 

 were formed. The studies of Professor Joseph Barrell, of Yale 

 University, published in the (Chicago) Journal of Geology for 

 1908, deserve especial mention in this connection ; for they have 

 clearly set forth the characteristics of continental formations in 

 contrast to marine formations, and they have further suggested a 

 variety of tests by which the climate under which continental de- 

 posits were formed may be inferred. Under an ordinary or normal 

 climate, neither glacial nor arid, land-laid stratified deposits are 

 chiefly the work of aggrading streams, and as such they will be 

 characterized through the greater part of their mass by frequent 

 and irregular changes in texture, with cross-bedding, lateral un- 

 conformities, red color, ripple marks, rain prints and mud cracks. 

 Evidently then the detailed structure of continental formations in 

 high latitudes may be nearly as significant of mild climate as is the 

 occurrence of fossil land plants. Furthermore, the formation of 



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