to the Town of Geclong. 43 



escapes to the surface by simple pressure, rising through the 

 faults or fissures which may have been formed as before ex- 

 plained, or other exciting causes. This, when evaporated by 

 our dry atmosphere, in these lagoons, accounts for the crust 

 of salt found in and around them in such quantities. 



As the bed of the rock salt is dissolved by the motion of 

 water over it, it becomes brine, and on making its way to the 

 surface, leaving a vacuum, the outer crust will naturally sink, 

 and follow the wasting away of the rock ; accordingly we 

 find these lagoons formed, and I doubt not increasing in 

 depth, but so imperceptibly as scarcely to excite a passing 

 notice. It is a well-known fact that such has taken place in 

 the mother country, at Northwich and other salt neighbour- 

 hoods, where land formerly elevated is now submerged many 

 feet under water. No doubt this sinking in the old country 

 will, and does take place much more rapidly than with us, 

 which is easily accounted for when I state that it is no unusual 

 thing at many of these places to pump up an average of a 

 thousand million gallons of salt brine per year. 



I should mention, that generally, under this first or upper 

 bed of rock salt [(that is between the first and second beds), 

 is to be found a stratum, of ten yards or so in thickness, con- 

 taining no particle of salt, but quite impermeable to water ; 

 it is therefore quite natural to expect that the brine from the 

 upper layer will make its way to the surface, just as we 

 find it. 



To return : — Being foiled by the impurities of the sources 

 of supply which offered themselves in the neighbourhood of 

 the town, I turned my attention to the source of the Barwon 

 itself, to the elevated districts — the high and densely-timbered 

 ranges, which, as an outlying belt, intercepts and condenses 

 the rain-bearing clouds from abrupt contact with the satu- 

 rated volume of air, highly charged with humidity from the 

 Southern Ocean, carried landward by the prevailing winds, 

 and, so far as I have been enabled to judge from the geo- 

 logical structure of the country, its general configuration, its 

 wild and precipitous glens, its systems of deeply-indented 

 ravines, abrupt hills, deep creeks, elevated ranges, and exten- 

 sive gullies, all tend to the belief — in the absence of any well- 

 founded meteorological data, or even statistical information 

 to go on — that the local and visible effects have been pro- 

 duced by the copious outpourings, amounting to torrents of 

 rain, which must have been supplied from the condensing va- 

 pours precipitated on its surface ; a surface proving the hu- 



