40 THE UNDERGROUND WATERS OF NORTH-WEST YORKSHIRE. 
(Fig. 2). When the escape is along both sides of a valley the 
saturation planes will generally slope in the same direction as 
the sides of the valley but at a lower angle (Fig. 3). 
Fic. 2. 
2. The greater facility of percolation or flow in a given 
direction, as compared with that in another direction, will have 
the effect of producing a saturation plane of lower gradient in 
Fig. 3. 
the direction of easiest movement. Thus we find that the 
saturation gradient is generally gentler in the direction of the 
dip of rocks than towards the rise, e.g., the cone of exhaustion 
produced by pumping from a well or borehole in inclined beds has 
its axis inclined in the direction of the dip (Fig. 4) ; and on 
a given outcrop of inclined strata, the subterranean watershed, 
