686 W. M. DAVIS 



limitation to man, and become the study of temporary floras and 

 faunas in successive geographies; while biology would give up its 

 usual meaning and become the study of life in the developmental 

 sequence of organic evolution through geological time. The study 

 of the minerals and rocks of any epoch would be minerography and 

 petrography, while mineralogy and petrology would treat problems 

 of paragenesis and metamorphism in which the passage of time is 

 essential; and for one, I should then be able to remember what 

 petrography and petrology mean. So we might go on with physiol- 

 ogy, meteorology, and oceanology as made up of a succession of 

 physiographies, meteorographies, and oceanographies, and we should 

 have glaciology and climatology made up of glaciography and clima- 

 tography; and ontology or the sequence of organic responses to the 

 changing earth, would be made up of a succession of ontographies. 



Schemes of terminology, however, are not often successfully made 

 to order in this fashion ; they are slowly evolved without much regard 

 to system, as is seen in the haphazard nomenclature of oceans, seas, 

 gulfs, and bays. Minerography is strange to the point of offense to the 

 ear; we cannot-take over biography and physiology from their present 

 uses ; we must get along with the terms that we have, and with such 

 new ones as are added from time to time. My only object in sug- 

 gesting this fanciful scheme is to bring more clearly forward the space- 

 and time-relations that are recognizable in all branches of our subject, 

 as well as in geography and geology. The progress of the last century 

 has certainly brought us now to a stage when these general relation- 

 ships may be in good part understood, if we give heed to them. We 

 fail to take the best advantage of our progress if we see only the spe- 

 cialized development of our several subsciences. 



It has often seemed to me as if petrologists were rather overwhelmed 

 at present with the flood of new facts that modern methods of research 

 have let loose upon them ; yet how greatly is the study of both mineral- 

 ogy and petrography broadened by the addition of the continuous 

 to the momentary consideration of minerals and rocks that the flood 

 has swept before us; for even the rocks have their phases of youth 

 and age. So brief is our life that geomorphologists are even today 

 hardly accustomed to the systematic mobilization of land forms; yet 

 the description of the lands is greatly strengthened when their forms 



