102 



refraction, discovers a thicket of broom of about one foot and a 

 half high. 



With the exception of the scored face of the escarpment of 

 the Bunda cliffs about "Wilson's Bluff, and that around the 

 Pidinga rock basin, the whole region shows no traces of flowing 

 water. Not only is this so for the Bunda Plateau, but is 

 equally true for the whole coast line to near Port Lincoln. 



Geology of the Bunda Plateau. 



Introduction. — Since the time when Eyre described the Bunda 

 cliffs as being composed for the most part of white chalk with 

 layers of flints, the interest of geologists has ever been active 

 to know if the rock be a true chalk. 



Capt. Elinders conjectured " the evidently calcareous nature 

 of the bank " to be the exterior line of some vast coral reef, 

 and broached the daring theory that its present elevation arises 

 from the gradual subsiding of the sea, or perhaps from some 

 convulsion of nature. 



Eyre confirms the description of Elinders, and gives a 

 detailed and accurate account of the stratification of the cliffs, 

 estimating their height at 300 to 400 feet. 



Sturt, in alluding to Elinders' opinion, says : — " The only 

 point we differ upon is as to the probable origin af the great 

 sea-wall. Had Capt. Elinders been able to examine the rock 

 formations he would have found that it was for the most part 

 an oolitic limestone with many shells embedded in it, similar 

 in structure and formation to the fossil beds of the Murray, 

 but differing in colour." All this is a contradiction of Elinders 

 and Eyre, and a misrepresentation of observations made by 

 the latter, who describes the upper surface of the country to 

 consist of a calcareous oolitic limestone, below which is a hard 

 concrete substance of sand and soil mixed with shells and 

 pebbles. Below this again the principal portion of the cliff 

 consisted of a very hard and coarse grey limestone, and below 

 it a gritty chalk. 



Eyre is, however, wrong in describing the superficial rock as 

 an oolitic limestone, and Sturt is equally inaccurate in com- 

 paring it with the prevailing stone in the Murray cliffs. 

 " Upon what data Captain Sturt made such statements he does 

 not tell lis, but it may be here noticed that he thought the beds 

 were continuous with those he obseiwed inland, that is, on the 

 banks of Lake Torrens." — Woods' Greol. Observations in S. A., 

 p. 117. 



This guess of Sturt's, which proves to be not far from the 

 truth, seems to have been adopted by subsequent authors, as 

 the Eev. J. E. T. Woods classifies the rocks of this country 

 among "the older tertiaries, and Mr. B. Brough Smyth has 



