BY JOHN FALCONER, C.E. 



31 



lie off the coast are the remains of a range which formed the 

 eastern lip of a basin which is now Torres Straits. On a good 

 many, and probably on all, of these islands good water may be 

 obtained by boring into the strata, which dip towards the west. 

 The large springs on the Lizard Island, and on No. i Howick 

 Group, close to which Mrs. Watson and her baby died of thirst, 

 are examples of springs supplied by the main land. The water 

 accumulates between the strata coming out at the outcrop which 

 forms the Barrier Reef. A good deal of this water, however, 

 which gets in on the sea slopes of the Coast Range, bubbles up 

 under the sea, as between Noosa and Double Island Point, or on 

 the islands off the coast. The places where fresh water gains the 

 surface beneath the sea are indicated by an immense growth of 

 oysters and other shell-fish and coral, as life of this description 

 seems to flourish best where the salt water is diluted. Where 

 there is no coral, an an opening through the reef occurs, it is 

 observed that the nearest head-land on the main-land is granite. 



Class IV.—" Billa-Bongs." 



" Billa-Bongs" (PI. ix.) are due to the water in its course 

 along the beds of old channels already filled in, being dammed 

 back by the occurrence of n? ural barriers. These originate at 

 times of periodical floods, • /hen the surface water, in sweep- 

 ing over the land, is charger with the smaller particles of loam 

 which, by accumulation, fo m beds of impervious clay at points 

 favoring their occurrence in these channels. The water being 

 dammed back rises to t\e surface, and forms springs or water- 

 holes, in which it is ma'atained at a constant level by the con- 

 tinuous supply from a' ove. In the absence of springs of this 

 description, driven tv jq wells will generally make these waters 

 available on the surf ce, and have been very successfully applied 

 in this country and Abyssinia. 



Water exists xt a depth of from twenty to fifty feet in all the 

 Spinifex and De dvt country. 



On Wona linda Station, Mitchell, a good sized creek looses 

 itself in a gr ge, and flows underground. It in all probability 

 lodges somev nere between there and the southern border of the 

 colony, and may supply the sprmgs both hot and cold which 

 appear at ( ooper's Creek, and which have very likely formed the 

 opal beds .n that neighborhood, which appear to be only dried-up 

 hot sprir js. This creek is highly charged with silica, and in 

 eroding its way through the rock has lined the gorge with a coat- 



