THE UNDERGROUND WATERS OF NORTH-WEST YORKSHIRE. 
23 
escarpment falling to the line of the middle fault. The southern 
area consists of sharply undulating Bowland Shales, through 
which appears, in two outcrops, the Pendleside Limestone, with 
the characteristic knoll-reefs of Tiddeman. In the northern 
belt there originate three streams w^hich have been the subjects 
of investigation. They suffer total or partial absorption upon 
entering the median zone of strongly-jointed limestone, and the 
water is given out in three principal springs, two of which, at 
Malham Cove and Gordale respectively, come out at the foot of 
the great escarpment, while the third. Aire Head, emerges at the 
southern edge of a synclinal fold of the Bowland Shales. 
Summary of Results. 
It may be convenient to briefly relate the results obtained 
from the investigations of the Chemical and Engineering Sub- 
Committees, and those previously recorded by Mr. Tate. 
A. Chemical. 
1. Reagents introduced into the Smelt Mill Sink have 
been traced nowhere except at the Cove. 
2. The ammonium sulphate supplied to the Tarn effluent 
stream in June, 1899, though almost exclusively discharged by 
the Aire Head Springs, 3-et was traceable in minute quantities 
in the water flowing from Malham Cove on July 4th to 11th. 
(It is important to note that it synchronised exactly with 
the discharge of the same reagent at Aire Head.) 
3. The ammonium sulphate placed in Gordale Beck 
reappeared in the springs at the foot of Gordale Scar, and 
nowhere else. 
4. The fluorescein poured into the bottom of Grey Gill 
Cave has not been traced. 
5. The salt introduced into Cawden Burst came out at 
Mire's Barn Spring about a quarter of a mile to the southward- 
