2(10 EARTHQUAKES IN NORTH CAROLINA. 



falling. Now, if we assume that the region around Stone Mountain is 

 undergoing a very gradual elevation or depression, then it will follow 

 that the rocky strata will be brought into a condition of stretcliing or 

 tension which will go on until the limit of elastic cohesion is reached, 

 when a rupture or crack will suddeuly take place which must be at- 

 tended with a jar, and, in some cases, with an audible sound. If the 

 rocky strata is of the same material from the surface down into the inte- 

 rior ; for example, granite, and the mountain being in the process of 

 depression, the crack will take place deep in the interior. If, on the 

 other hand, the mountain is being elevated, the crack will be at the 

 surface. If, however, the upper strata are more extensible than the 

 deeper seated, the crack may be in the interior in the case of an eleva- 

 tion as well as in that of a depression. 



It has of late years been suspected, from the discrepancy in later 

 and older measurements of points on the Andes, that this mountain 

 system is in a state of very slow subsidence. 



If the foregoing views are correct there is no indication of a volcanic 

 outburst; and whatever moral effect the disturbances may have on 

 the character of the inhabitants of the region, there is little danger as 

 to any j^hysical changes taking place of sufficient intensity to endanger 

 life.— J. H.] 



