396 



DYNAMICAL GEOLOGY. 



degree of latitude makes a complete revolution in 38-6 days, while the 

 equator revolves in 25*5 days. 



The fact of torsion appears thus to be sustained for the other planets 

 as well as for the earth. 



348. 



Oblique feature-lines on Mars. Prinz. 



Prinz introduces, in closing, the diagram in Fig. 349 to illustrate the 

 general scheme of torsional movements. He implies that such movement may 



have begun in the incipient 

 stages of surface consolida- 

 tion, whenever the continen- 

 tal and oceanic areas began 

 to be differentiated, and that 

 in the process a cleavage 

 structure was produced that 

 determined the system of 

 fractures in the earth's sur- 

 face, and thereby the system 

 in the earth's feature -lines. 

 But he adds that the solu- 

 tion of all the questions that 

 arise demands the profound- 

 est knowledge of celestial 

 mechanics, as well as much 

 experiment, and a complete discussion of the records in the earth's structure. 



Historical geology adds greatly to the interest of geomorphic work, by 

 presenting in detail the connection of mountain-making movements with the 

 preparatory stratigraphic events, and also by bringing out to view the bear- 

 ings of these great topographical changes on the physical conditions of the 

 earth, and their influence on biological distribution and progress. 



