298 



Scientific Proceedings, Royal Dublin Society. 



regional metamorphism, and consequent folding of the altered 

 rocks after a period of quiescence. . 



Fig. 3. 

 Folding of a previously metamorphosed region, under the area of a new dome or bulge, A, A. 



4th. Owing to an excess of denudation on one side of an 

 elevated area, or other cause, subsidence on one flank of such an 

 elevation might differ from that on the other ; when the tangential 

 thrust from each side, overcoming friction, and acting in parallel 

 but not directly opposed lines, the rock masses of one side would 

 have a tendency to pass over or under those pressed towards them 

 from the opposite direction, the overlying rocks tending to move 

 upward towards the position of least resistance, and this transitive 

 action might be continued even until the surface was reached, or 

 at least the thrust masses had come within reach of exposure by 

 denudation. 



Fig. i. 



Ultimate result of the earth movements, which may produce folding and metamorphism. 

 T, a major thrust planejxxxxxx minor thrusts. Arrows show direction of unequally 

 opposed motion. 



Mr. Kilroe's suggestions, here condensed, however theoretical 

 or tentative, convey at least the impression of affording a satisfac- 

 tory explanation of those features connected with earth movements 

 which have been under consideration. And it may be hoped that 



