GENERAL PRINCIPLES — CONCLUDED 33 



history is sub-divided according to great predominant physical or 

 organic phenomena as, for example, the "Appalachian Revolution" 

 (toward the close of the Paleozoic era), the " Rocky Mountain 

 Revolution" (toward the close of the Mesozoic era), the "Age of 

 Fishes" (Devonian period), the "Age of Mammals" (Cenozoic era). 

 Students of earth history, like students of human history, must 

 be very careful to make a distinction between events and records 

 of events, because by no means all historical events are recorded. 

 Events are continuous, while their records are usually much inter- 

 rupted and apparently sharply separated from each other. In both 

 geologic and human history, times or periods of comparatively 

 quiet and slow change have often given way to times of compara- 

 tively rapid, to even revolutionary, change. 



Selected General References 



Willis: Index to the Stratigraphy of North America, Accompanied by a Geo- 

 logic Map of North America. Prof. Paper 71, U. S. Geol. Survey. A 

 very comprehensive work with many references and quotations. 



Chamberlin and Salisbury: Geology, Vols. 2 and 3 (Henry Holt Co., 1906). 

 A very elaborate recent American work. 



Chamberlin and Salisbury: College Geology, Part 2 (Henry Holt Co., 1909). 

 A briefer discussion than in the larger work of these authors. 



Dana: Manual of Geology, Part 4 (American Book Co., 1895). A very elabo- 

 rate older American work. 



Geikie: Text-book of Geology, Vol. 2 (Macmillan Co., 1903). A comprehensive 

 English work with emphasis upon European geology. 



Kayser: Lehrbuch der Geologie, Part 2 (F. Enke, Stuttgart, 1912). A com- 

 prehensive German work with emphasis upon European geology. 



Haug: Traite de Geologie, Vol. 2 (A. Colin, Paris, 1911). A comprehensive 

 French work with emphasis upon European geology. 



Willis and Salisbury: Outlines of Geologic History with Especial Reference 

 to North America (University of Chicago Press, 1910). Not a text-book, 

 but contains important general papers by various American geologists. 



Blackwelder: Regional Geology of the United States of North America (Stechert 

 & Co., 1912). Contains brief outlines of the stratigraphy and geologic 

 history of the United States. 



Le Conte: Elements of Geology, Part 3 (Appleton and Co.) An older fairly 

 comprehensive treatment of historical geology with special reference to 

 North America. 



Scott: An Introduction to Geology, Part 4 (Macmillan Co., 1907). A fairly 

 comprehensive discussion of earth history. 



Pirsson and Schuchert: Text-book of Geology, Part 2 (John Wiley & Sons, 

 1915). A fairly comprehensive treatment of historical geology. 



Cleland: Geology, Physical and Historical, Part 2 (American Book Co., 

 1916). A fairly comprehensive treatment of historical geology. 



