256 



The underground features are as remarkable as the sur- 

 face features. In 1907 a Government bore was put down 

 on this plain, on the jiublic road adjoining Section 64, Hun- 

 dred of Walloway, and within about two miles of Orroroo. 

 This bore, as will be seen from the following official report, 

 penetrated alluvial sands, clays, and gravels to a depth of 

 591 ft. without reaching: hard rock: — 



Particulars of 



Orroroo Bor 



e. 



Description of Strata. 



Thickness 



Depth from 





in feet. 



Surface. 



Loam 



.. 37 



37 



Gravel and clay ... 



.. 40 



77 



Sand and limestone 



1 6 in. 



78 6 in 



Yellow clay 



... 10 



88 6 in 



Sand 



6 in. 



89 



Clay 



... 68 



157 



Sandy clay 



... 5 



162 



Various coloured clays 



.. 168 



330 



Pipeclay 



.. 20 



350 



Sand and clay 



.. 27 



377 



Clay 



3 



380 



Soft white sandstone 



.. 42 



422 



Fine white sand ... 



.. 11 



433 



White clay 



9 



442 



White sand 



.. 8 



450 



Clay — white and pink 



.. 52 



502 



Quartz sand 



2 



504 



White clay 



^. 8 



512 



Quartz sand 



.. 18 



530 



Sand and pebbles 



.. 17 



547 



Sand, lignite, and clay 



.. 21 



568 



Quartz sand and clay 



.. 15 



583 



Sandy clay 



.. 8 



591 



Water was struck in the bore at 45 ft. Fresh water 

 that rose to surface was tapped at the respective depths of 

 350 ft., 380 ft., and 502 ft. The choking of the bore un- 

 fortunately stopped further exploration. 



This remarkable result proves that the Black Rock, 

 Orroi^oo, and Walloway Plain was at one time in the line 

 of a gieat artery of drainage that ran north and south, and 

 that the old trunk river flowed, at a certain period of its 

 history, not less than 600 ft. below the present level of the 

 plain. 



What happened to that old river that it should have 

 been so completely wiped out of existence ? 



