COLLAPSE OF RECENT BEDS AT STAUNTON 49 



above the limestone roof of the cavern before the larger breaks 

 in the limestone roof occurred. Such a temporary cavity in the 

 marl superimposed upon the limestone cavern might, when it 

 collapsed, precipitate tons of clay and marl with destructive 

 effect upon the limestone roof which, under normal conditions, 

 would have remained stable for ages. That the marl beds held abund- 

 ant water for such streams, if their development were stimulated and 

 an outlet provided by withdrawing the water from the cavern 

 beneath a portion of the beds, is indicated by the fact that a pump 

 at the Clem ice factory with a capacity of 50 gallons per minute 

 draws its water from these beds. Desication resulting from the 

 lowering of the ground water and the consequent shrinkage of the 

 materials which filled the old outlets of the original sink hole may 

 also have been a factor, though probably a minor one, in starting 

 the caving. Consideration of all the available evidence which has been 

 given appears to point to the lowering of the level of groundwater 

 by pumping as the most probable immediate cause of the caving. 



