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eastern side is a thick deposit of conglomerate. This con- 

 glomerate is composed of water-worn pebbles of a more or less 

 subangular form, and range in size from half an inch to eight 

 inches in diameter. According to Mr. H. T. L. Brown (Eeport 

 June, 1885), the constituents are chiefly " quartzite, jasper, 

 flint, chert, quartz, iron ore, grit, and sand, cemented with 

 silicious matter." 



This conglomerate forms the eastern portion or side of the 

 range, and, compared with the abrupt western side, it may be 

 described as sloping gradually to the level of the plain." A 

 section of this conglomerate, 500 feet high, forming the 

 southern end of the range, shows no appearance of stratifica- 

 tion. The face of this cliff is studded with shallow cavernous- 

 depressions formed by the breaking off of huge masses of the 

 conglomerate, which now form a long slope. 



The conglomerate forms the highest point of the Caroona 

 Hill, and is the site of a trigonometrical station, estimated to 

 be 1,200 feet above sea-level. This elevated portion forms a 

 ridge extending northwards, on either shoulder of which dis- 

 tinct patches of polished conglomerate may be traced for 

 upwards of two miles. 



As wells have been dug in close proximity to both sides of 

 the range aud to its southern extremity, some additional infor- 

 mation has been obtained as to the nature of the rocks below 

 the surface. The stratum on the western and eastern sides was. 

 after passing through the alluvium, a hard sandstone grit ; and 

 this notwithstanding that on the eastern side the deposit of 

 the conglomerate was within a few hundred yards. On the 

 southern side, however, the sinking was entirely in the con- 

 glomerate, which was not pierced through at a depth of 60 feet^ 

 thus showing that at a former period the cliff had extended 

 further to the southward, but was gradually becoming weathered 

 back northwards. On the north-west corner of the range a 

 well was sunk to a depth of 120 feet, and bottomed on lime- 

 stone and a very hard quartzitic porphyrite, containing distinct 

 crystals of feldspar. On the eastern plain, between the 

 Caroona Hill Eange and the " Lincoln G-ap" hills, two wells 

 have been sunk through the alluvium, and both bottomed on a 

 blue clay-slate. The situation of one was six miles from 

 Caroona Hill ; that of the other 22 miles. It is noteworthy 

 that no sandstone was met with in either. 



Mr. Brown, in his report (1885) refers to the existence of a 

 valley or basin between Port Augusta and the nearest " Lincoln 

 Gap" hills, now filled with Tertiary material ; and he hints at 

 underlying " Cretaceous" rocks. He also speaks of a similar 

 valley or basin on the western side of the " Lincoln Gap" hills. 



There seems then to be evidence of the existence at one time- 



