134 



Fig. 1. Showing the effects of bedding 

 planes where the stream has cut down rap- 

 idly (A) and slowly (B). 



Fig. 2. Showing the effect of long con- 

 tinued lateral erosion. The dotted line 

 shows the curve of greatest strength. 



Fig. 3. Showing collapse due to weak- 

 ness from lateral erosion. The cave has 

 assumed the curve of greatest strength. 



Fig. 4. The solid lines show the original 

 cave and the dotted lines the course the 

 stream will seek to pursue. 



Fig. 5. Effect of unusually 

 soft or soluble rock. 



Fig. 6. Dome. 



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Fig. 7. Fit and dome. 



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Fig- 8. Progression of a cave entrance up a slope. 



