20 PRINCIPLES OF STRATIGRAPHY 



Inorganic 

 Atmology (Meteorology) 



( Oceanography (Oceanology) 



Hydrology j Limnology 



^ Potamology 

 Geology "j Lithology (Petrology, Geology in the narrow sense) 

 Pyrogeology (Vulcanology) 

 Organic 



f Zoology (including palaeozoology) 



Biology \ Phytology (Botany) including palaso- 



'' botany 



Since no direct study of the Centrosphere is possible, no corre- 

 sponding science has been developed. (See, however, Chapter 

 XXIII.) 



Each branch or science may again be treated under the follow- 

 ing headings : dynamics, structure, and history or genetics. Dynami- 

 cal geology in the broadest sense deals with the physical and chemi- 

 cal forces and tlieir working. In the narrow sense, dynamical 

 geology is dynamical lithology, or the working of the physical and 

 chemical forces in and upon the earth's crust. Dynamical biology is 

 designated physiology. Hydrology and atmology (meteorology) are 

 largely a treatment from the dynamic point of view of the water 

 and the atmosphere, respectively, dealing especially with the move- 

 ments of these. Volcanic manifestations illustrate the dynamics of 

 the pyrosphere, or p\rod\namics, while earthquakes illustrate the 

 dynamics of the centrosphere, or rather their effect upon the litho- 

 sphere. The interaction of the spheres upon one another must here 

 be considered as developing the exogenous dynamic forces. Thus 

 the action of the atmosphere, hydrosphere, biosphere, and pyro- 

 sphere upon the lithosphere furnishes the exogenous dynamic prod- 

 ucts which are manifested chiefly in the clastic rocks; while the en- 

 dogenous dynamic forces reside within the material of the earth's 

 crust, and are manifested in chemical combinations, in crystalliza- 

 tion, etc. 



From the point of view of structure, structural lithology (struc- 

 tural geology in the narrower sense) deals with the composition 

 and arrangement of the material of the earth's crust, and comprises: 

 I, elements; 2, minerals (mineralogy) ; 3, rocks (petrology, petrog- 

 raphy, lithology in the narrower sense) ; 4, large structural fea- 

 tures (geotectology or the study of the architecture of the earth's 

 crust) ; 5, the surface features (lithomorphology, physical geogra- 

 phy). Structural biology comprises the study of: i, the cell (cytol- 

 ogy) ; 2, the tissues (histology) ; 3, the larger structures (anatomy) ; 



