54 MERIDIONAL UNDULATIONS AND FRACTURES. 



a plain, drifted by wind alone, and it is the form of snow- 

 drifts the point of the wedge being towards the source of 

 action. Whether water, or wind, or both, acting con- 

 tinuously, have been agents in these conformations ; whether, 

 in contracting or expanding, the earth's surface or crust 

 has had a tendency to scale-like fracturing, must be left to 

 the consideration of competent judges." 



These conformations, observed by Admiral Fitzroy, 

 appear clearly to coincide with such as might natu- 

 rally be expected to result from the alternate con- 

 junction and opposition of the vis inertise forces 

 acting in combination with the undulating tendency 

 of lateral pressure. 



196. We observed in chapter iii. tbat tbe centri- 

 fugal force resulting from axial rotation might be 

 expected in some measure to neutralise the undu- 

 lating action of lateral pressure acting north and 

 south, so that the greatest apparent effects of undu- 

 lating force should result from the pressure acting 

 east and west. This would not, however, account 

 for any one of the meridional undulations being 

 greater than any other. But, as far as the forces 

 which we have thus far brought into play are con- 

 cerned, all the meridional undulations on our hypo- 

 thetical globe would be equal and similar. There 

 are, however, on the surface of the earth two meri- 

 dional undulations immensely greater than all others, 

 the crests of which form respectively the Old and 

 New Worlds; and the depressions between them con- 



