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these curvatures affect the contour of the surface, they 

 are apt to do to exactly in the opposite way to that 

 the learner might have anticipated The anticlinal 

 folds not unusually coincide with, and have given rise to, 

 lines of valley ; while the synclinal folds have originated 

 lines of ridge or hill. 



Hut the observer as he extends his experience will find 



FW. 47-0 



that not only have the rocks of the earth's crust been 

 folded in this equable and gentle way; but that they 

 present proofs of much more intense movement. These 

 may be looked for in the vicinity of faults, as has already 

 been pointed out Sudden and violent crumpling in 

 the midst of comparatively undisturbed strata may be 

 regarded as primd fade indicative of the proximity of 



