366 A. p. COLEMAN GLACIAL PERIODS AND GEOLOGICAL THEORIES 



to our knowledge of ancient glacial periods. His discussion of the causes 

 of ice ages also is suggestive and worthy of note. 



The series of papers as a whole shows how lively an interest is now 

 being taken in ancient climatology, and also how divergent the views are 

 of the various geologists who are attacking the subject. 



