INORGANIC GEOLOGICAL DYNAMICS. 613 



naturally suggested by the subterraneous increase-' 

 of temperatures, but explains the spheroidal figure 

 of the earth ; and falls in with almost any theory 

 which can be devised, of volcanoes, earthquakes, 

 and great geological changes. 



Sect. 5. Problems respecting Elevations and 

 Crystalline Forces. 



OTHER problems respecting the forces by which 

 great masses of the earth's crust have been dis- 

 placed, have also been solved by various mathema- 

 ticians. It has been maintained by Von Buch that 

 there occur, in various places, craters of elevation ; 

 this is, mountain-masses resembling the craters of 

 volcanoes, but really produced by an expansive 

 force from below, bursting an aperture through 

 horizontal strata, and elevating them in a conical 

 form. Against this doctrine, as exemplified in the 

 most noted instances, strong arguments have been 

 adduced by other geologists. Yet the protrusion 

 of fused rock by subterraneous forces upon a large 

 scale is not denied: and how far the examples of 

 such operations may, in any cases, be termed craters 

 of elevation, must be considered as a question not 

 yet decided. On the supposition of the truth of 

 Von Buch's doctrine, M. de Beaumont has calcu- 

 lated the relations of position, the fissures, &c., 

 which would arise. And Mr. Hopkins *, of Cam- 



8 Trans. Camb. Phil. Soc. vol. vi. 1836. 



