52 COMBINED ACTION OF AXIAL ROTATION, 



zones instead of being continuous are intersected by 

 undulations running north and south. 



194. We have, however, as yet applied only the 

 dynamic forces of axial rotation, and onward motion 

 through space. Let us consider the action of the 

 third dynamic force, or evanescence. The tendency to 

 contraction, resulting from this evanescence, induces 

 lateral pressure throughout the outer crust of the 

 earth; and if that outer crust have not sufficient 

 strength to resist the action of gravitation; it must, 

 if sufficiently pliant, have a tendency to undulate all 

 over; or, if not sufficiently pliant to undulate, its 

 tendency must then be to shiver to fragments. 

 Let us consider in what manner this tendency to 

 undulate or to fracture can take effect. 



195. We have seen that the vis inertia force 

 resulting from axial rotation, and that resulting from 

 orbital motion, both act westwards in any given part 

 of the surface of the earth when that part of the 

 surface is turned from the sun, but as soon as that 

 part of the surface reaches the point of sunrise, then 

 the conjoint action of those forces ceases; the orbital 

 force of vis inertiae abruptly turns eastwards, and acts 

 in opposition to the force of vis inertiae resulting from 

 axial rotation. Thus, then, the alternate conjunction 

 and opposition of these forces of vis inertias would 

 control the undulating action of lateral pressure; 

 and cause those undulations to take the form of a 

 series of ocean waves sweeping westwards. These, 



