270 UNDERGROUND WATERS OF NORTH-WEST YORKSHIRE. 
In the case of Ingleborough the impervious shales of the 
^'oredale Series give rise to surface streams which, as already 
described, flow on to the limestone plateau and are swallowed 
by the various pot-holes. 
On Xorber and Moughton, however, the limestone plateau 
has no such covering of shales, Avith the result that no surface 
streams are formed, the rain being absorbed as it falls by the 
joints in the limestone. 
Under these circumstances it is of course impossible to 
trace the lines of flow of the underground waters which must, 
however, collect into somewhat definite channels, as there are 
many powerful springs round the base of both these hills. These 
springs are thrown out at or immediately above the line of 
junction of the limestone with the underlying impervious rocks, 
and the direction of underground flow will doubtless be controlled 
by the irregularities in the surface of the latter. 
Thus in the case of Xorber [Pis. XXII. and XXVI.] the 
springs S 20, S 21, S 22, S 23, S 24, S 25 and S 26 lying to the 
south of the Silurian ridge were unaffected by reagents intro- 
duced into the various pot-holes to the north of that ridge, and 
therefore probably receive their supply from the general surface 
soakage on the bare limestone " clints " which form the summit 
of the hill. 
Again, in the case of Moughton a small spring, S 29a, on 
Thieves Moss, which rises at the foot of the upper escarpment 
and almost immediately sinks again, reappears as the small 
spring at Capple Bank Wood S 29, but to the south of that point 
not one of the springs was affected by the reagents introduced 
on the main plateau. 
Moughton, therefore, hke Xorber, possesses an underground 
drainage quite independent of that of the main plateau, but 
the absence of surface streams and of definite water sinks again 
prevented the application of tests. 
The portion of Moughton to the north of the Silurian ridge 
is drained by Moughton Sike S 30 on the west, and by S 35, 
S 35a, S 36, S 36a, S 36b, S 36c, S 36d, S 37, S 37a and S 38, 
most of which are wet weather springs only, running dry in 
