1S59.] WOODS TERTIARY ROCKS. 259 



occasion a boat was lowered down to this, and a party of settlers floated 

 along the surface for half a mile ; and, though they then turned back, 

 they alleged that the passage was as wide as ever and could have 

 been followed to a much greater distance. On this body of water a 

 distinct current is perceptible after the rainy season, and doubtless 

 this is one of many underground rivers by which a large tract of 

 country, unprovided with any other means of drainage, gets rid of 

 its surface-water. This may be the cause of all the caves ; but 

 why they should always occur on the higher ranges and not upon 

 the flats, does not appear very clear according to such a theory. 



There are other facts which tend to show that some parts of the 

 country are being drained by underground channels. Thus in 

 certain localities on the Mosquito Plains all the wells are observed 

 to have a distinct current to the north-west. Again, I noticed, in 

 following the current of a large overflowing swamp, that the water 

 disappeared at the foot of a limestone-ridge (in which there were 

 only a few crevices) and became lost. Now at a place on the coast, 

 N.W". of the Mosquito Plains (Lake Eliza, marked on the map), and 

 at two places near the sea, south of the caves at Mount Gambier, 

 natural fountains are found, where the water rises from holes in 

 the rock in a fountain of some height, which must send up many 

 gallons of water per minute. There may be many others which are 

 not known, for the coast has been but little explored. At all events 

 the existence of a chain of freshwater lakes along the coast, con- 

 taining much more water than can be accounted for by the annual 

 fall of rain, would seem to indicate an underground drainage ; for it 

 is known not to come along the surface. The channels made by the 

 passage of this water will certainly become caves, shoidd the land be 

 hereafter sufficiently upheaved to leave them dry. 



I have never been able to find bones in any caves but those of 

 the Mosquito Plains, except in one or two shallow ones, where, 

 though imbedded in stalagmite, they were all of existing species ; 

 and the aperture was always in such a position on the roof that 

 animals, bounding across them, would be most likely to fall in. I 

 met with one curious instance of how caves of this description might 

 become full of animal remains. In exploring one near the coast, 

 which had never been entered before, 1 crepl along a gallery which 

 led into a large chamber, in the centre of thereof of which there 

 was a round hole about 2 feci wide. Underneath this was seen 

 a large heap of Kangaroo hones ; and skeletons were distributed 

 about the chamber. On coming to the surface I found that the hole 



was almost perfectly concealed by grass, that an animal might 



jump into it without suspecting the existence of an aperture. Some 



might be killed immediately, and >o Leave their bones on the heap, 



while others would struggle about the (handier and leave their 

 skeletons around. 



I have now enumerated a few of the remarkable features of this 

 extrusive district, in which, though nearly 1.0,920 Bquare-miles in 



extent, there are only our m- two small patches where the deposit 



differs from the formation which 1 am led to believe is oi an E 



