42 HOBBS— THE FIXED GLACIAL ANTICYCLONE. 



climatic zonation, as I pointed out in 1916.' We are living today in 

 the waning hemicycle of one of these abnormal glacial periods, and 

 as a consequence have reconstructed much of the past geologic his- 

 tory, not upon the standard or typical pattern of the earth, but upon 

 a markedly abnormal, short-lived and seldom occurring set of condi- 

 tions which happens to be the one in which we are living. 



University of Michigan, 

 September 14, 1920. 



■^ W. H. Hobbs, " The Ferrel Doctrine of Polar Calms and its Disproof 

 in Recent Observations," Proc. Second Pan-Am. Sci. Congress, Washington, 

 1915-16, sec. 2, pp. 185-187. 



