12 ] 
RECORDS OF V/.A. MUSEUM. 
increasing considerably in width and height when conditions are 
favourable. As a general rule the upper contour of the underlying 
granite forms the bed of the stream, but a very hard band of the 
limestone will answer the same purpose, though not in so satisfactory 
a manner. We have an example of this in the Mammoth Cave, 
for the blocks of limestone in the large main chamber (the 
size of which suggested its name) afford distinct evidence that 
formerly there were two caves, one above the other. In course of 
time the percolating water so weakened the limestone that formed 
the roof of one cavern and the floor of the other, that it collapsed, 
uniting the two into one huge chamber, the floor of which is strewn 
with large masses most of them hundreds of tons in weight. It 
was on the upper surface of one of these blocks, quite 70 ft. above 
the stream which flows through the cave, that the numerous 
specimens were collected. To an observer standing at that spot 
it is evident that the remains cannot have been introduced by way 
of the present entrance, which is about 70 ft. lower, for many of 
them bear unmistakable evidence of water transport. It was 
therefore necessary to seek another explanation for the presence of 
the bones at such a height above the present cave floor, and as the 
features observed tend to show that the double chamber evidently 
had existed, that solution may safely be adopted. 
The material in which the bones were embedded, varied 
somewhat in nature ; it comprised two groups, the lower and older 
series consisted of a reddish, fairly coarse sand, containing fragments 
of wood and gastropod shells in addition to the bones, with occa- 
sional bands of black loamy soil about an inch in thickness, which 
seem to prove the existence of floods in days gone by. Layers of 
stalactite often enclosing bones, wood fragments, etc., and bearing 
casts of eucalyptus leaves were not uncommon, one of these 
layers completely covered the series, thus protecting the animal 
remains and accounting for their fine state of preservation. 
Above this there was another sandy bed which was yellowish 
in colour ; the bones it contained were much fresher in appearance 
and are undoubtedly much more recent than the remains preserved 
in the lower series. 
A layer of stalactite varying greatly in thickness covered the 
lot, and it was not until this layer was pierced that the presence of 
