INORGANIC GEOLOGICAL DYNAMICS. 599 



treats : the aqueous causes of change, or those in 

 which water adds to, takes from, or transfers, the 

 materials of the land : the igneous causes ; volca- 

 noes, and, closely connected with them, earthquakes, 

 and the forces by which they are produced; the 

 calculations which determine, on physical principles, 

 the effects of assumed mechanical causes acting 

 upon large portions of the crust of the earth; 

 the effect of the forces, whatever they be, which 

 produce the crystalline texture of rocks, their fissile 

 structure, and the separation of materials, of which 

 we see the results in metalliferous veins. Again, 

 the estimation of the results of changes of tempe- 

 rature in the earth, whether operating by pressure, 

 expansion, or in any other way ; the effects of 

 assumed changes in the superficial condition, ex- 

 tent, and elevation, of terrestrial continents upon 

 the climates of the earth ; the effect of assumed 

 cosmical changes upon the temperature of this 

 planet; and researches of the same nature as these. 

 These researches are concerned with the causes 

 of change in the inorganic world ; but the subject 

 requires no less that we should investigate the 

 causes which may modify the forms and condition 

 of organic things ; and in the large sense in which 

 we have to use the phrase, we may include re- 

 searches on such subjects also as parts of Geological 

 Dynamics; although, in truth, this department of 

 physiology has been cultivated, as it well deserves 

 to be, independently of its bearing upon geological 



