44 THE UNDERGROUND WATERS OF NORTH-WEST YORKSHIRE. 
Cove to a flush from the Tarn Water Sinks, as compared with 
more prompt outflow at Aire Head, may be due to the flow 
taking place along a horizontal fissure, while that to Aire Head 
was through a vertical fissure. It seems unnecessary to appeal 
to such a cause, the existence and adequacy of which are alike 
uncertain. The causes assigned, namely, the interposition of an 
area of saturated rock and the difference between master-joints 
and cross-joints seem fully to account for the phenomena. 
The hypothetical cave which has been supposed to lie 
beneath the limestone plateau at Malham Cove rests upon no 
basis of observation, and, while all the facts can be explained 
without it, there are some which appear to be quite inconsistent 
with its existence. 
