DESCENT INTO ELDEN HOLE. O 



mechanical action of a flowing stream, therefore, can have 

 assisted the process of enlargement. 



That so deep a chasm should be entirely isolated is cer- 

 tainly remarkable, because it cannot be said to represent a 

 '' weak point towards which the rainfall has converged." 

 It must therefore be due to the gradual silent solvent 

 properties of rain-water falling on the surface and escaping 

 through jointings and insignificant channels in the hard 

 rocks below. Whether the excavation took place from 

 above or below is uncertain. Applying the rule " a ravine 

 is a cavern open to the sky,^' such an abyss is simply a 

 perpendicular cave whose roof has at length fallen in. But 

 there are many shallow funnel-shaped depressions in the 

 limestone to which this rule will not apply, and which have 

 been begun from the top ; and there are also holes of very 



Section of El den Hole, Derbyshire, September 1873. 



irregular shape, apparently of downward origin. So far 

 as the perpendicular shaft of Elden Hole is concerned, it is 

 not at all unlikely that the excavation descended from the 

 surface ; on the other hand, there are many underground 



