82 EXPEDITION FROM MORETON BAY [Nov. 8, 1858. 



known system of waters ; for, as Lake Torrens is decidedly only an 

 expanded continuation of Cooper Creek, and therefore the culmi- 

 nating point of this vast system of drainage, if there was sufficient 

 average fall of rain in the interior to balance the eftects of evapora- 

 tion from the surface of an extensive sheet of water, the " Torrens 

 Basin," instead of being occupied by salt marshes, in which the 

 existence of anything beyond shallow lagoons of salt water is yet 

 problematical, would be maintained as a permanent lake. 



Therefore, if the waters flowing from so large a tract of country 

 are insufficient to meet the evaporation from the surface of Lake 

 Torrens, there is even less probability of the waters of the western 

 interior forming an inland lake of any magnitude, even should there 

 be so anomalous a feature as a depression of the surface in which it 

 could be collected, especially as our knowledge of its limits indicates 

 a much drier climate and less favourable conformation of surface 

 than in the eastern division of the continent. 



The undulations of the surface of the country are nearly parallel 

 to the meridian, gradually decreasing in height from the dividing 

 range between the eastern and western waters till, instead of the 

 waters of the rivers being confined to valleys, they occupy plains 

 formed by a slight flattening of the curvature of the sphere. Thus 

 the sides of the plain through which the river ran before it turned 

 west to Cooper Creek were 150 feet below the tangential level of the 

 centre channels, and even the summit of the sandstone table land 

 which rose beyond was below the visible horizon. 



It is this peculiar conformation which causes the stream beds to 

 spread so widely when following the course of the valleys from north 

 to south, and it is only where they break through the intervening 

 ridges that the water is confined sufficiently to form well-defined 

 channels. 



The existence of these extensive valleys trending north and south 

 over so large a tract of country, renders it by no means unlikely that 

 they continue far beyond the limits of present explorations, and it 

 is not unreasonable to infer that the great depression which has been 

 traced nearly 500 miles north from Spencer Gulf through Lake 

 Torrens to the stony desert of Sturt (or rather the mud plains con- 

 tiguous to its western limit), may be continuous for an equal distance 

 beyond to the low land at the head of the Gulf of Carpentaria ; a 

 theory also supported by the fact, that the rivers flowing into the 

 Gulf either come from the east or west, apparently from higher land 

 in those directions, while there is not a single watercourse from the 

 soiith, or any indication of elevated country in that direction. 



With regard to the number and habits of the aborigines, I could 



