POULTOX : DOWKERBOTTOM CAVE. 
355 
some passage has been gradually dissolved away, and the lake 
drained, or a system of fissures supplying it with water may have 
become choked. 
Thus the deposits in this third chamber are chiefly mechani- 
cal in origin, consisting of the blocks fallen from the roof, and 
the stiff clay derived from the finest sediment slowly brought 
through narrow fissures to a lake in which no perceptible currents 
can have been present. Chemical deposits, represented by stalag- 
mite, elsewhere so abundant and thick, are only present as thin 
layers on those parts of the limestone blocks covered by the 
water of the lake and not sunk in the clay, and also where depos- 
ited by the drip from the roof upon the parts not covered by water. 
There are also very small stalactites on the roof, and thin layers 
of chemically formed limestone on the sides. It will be seen that 
chamber 2. now so different, for a long period resembled this 
chamber in the preponderance of mechanical over chemical 
deposits. 
The western division of the cave is far smaller than the other, 
it also consists of three chambers separated by two passages. 
The first chamber much resembles that on the E. side, only it is 
smaller. Its former condition is shewn in the section appended 
to Mr, Denny's paper, and exactly resembles that of the E. side ; 
the surface being covered by what is called a " charcoal layer." 
From the first chamber a narrow winding passage leads to the 
second chamber from which it is separated by a constricted 
aperture ; the floor of this small chamber is composed of hard 
stalagmite. Then follows a fall of the roof, the blocks firmly em- 
bedded in a large amount of hard stalagmite. In the upper part 
of this fall is a passage to the third chamber. The further end of 
this chamber, of which the floor is also covered with hard stalag- 
mite, narrows to a mere fissure filled nearly to the roof with fallen 
limestone blocks, along which one can make way for a few yards. 
The true floor at this end of the chamber is concealed under a 
vast heap of fallen blocks. 
