GEOLOGY 



PART I 



THE MATERIALS OF THE EARTH AND PROCESSES 

 WHICH AFFECT THEM 



CHAPTER I 

 PRELIMINARY OUTLINE 



Geology is the history of the earth and its inhabitants. It treats 

 of the rocks and of the agencies and processes which have made 

 them, and from the rocks, their structures, and their fossils, it 

 attempts to make out the stages through which the earth and the 

 life which has dwelt upon it, have passed. 



Subdivisions. So broad a science has many subdivisions. 

 Cosmic or Astronomic Geology treats of the outer relations of the 

 earth; Geognosy treats of the materials of the earth, and its most 

 important branch is Petrology, the science of rocks; Structural 

 Geology deals with the arrangement of the rocks; Dynamic Geology 

 deals with the forces involved in geologic processes; Physiographic 

 Geology treats of the face of the earth, or topographic form; while 

 Paleontologic Geology, or Paleontology, concerns itself with the fossils 

 that have been preserved in the rocks, and with the faunas and floras 

 that have lived in the past. The succession of events in the earth's 

 history constitutes Historical Geology, which is worked out chiefly 

 from the succession of beds of rock formed through the ages, and 

 from the fossils they contain. Besides these general subdivisions, 

 there are special applications of geologic knowledge which give rise 

 to other terms. Thus Economic Geology is concerned with the 

 industrial applications of geologic knowledge, and Mining Geology, 

 a sub-section of economic geology, deals with the application of 



