66 



north-east and a dip south-east at about 35°." The strata 

 flatten out further to the south-east, where an almost hori- 

 zontal impure limestone is conspicuous, leading up to the 

 Grampus Range, which latter is crossed within a mile or 

 two of the fertilizer claims. 



The Grampus Range is a jagged tent-hill ridge of quartz- 

 ite, flanked on either side by softer and more readily denud- 

 ing slaty strata. The main quartzite bed is about 25 ft. thick 

 (striking about N. 74'' E., and dipping 69° to the north). It 

 can be traced for some fifteen miles on either side boldly out- 

 cropping across the plains in an almost linear direction. At 

 the trigonometrical station on top of Grampus Hill, a re- 

 markable view is unfolded. From that high point the dreary 

 prospect of barren saltbush plains is relieved, and the effect 

 of arid weathering on the rocky pedestal itself correspondingly 

 accentuated. 



On the south side of Grampus Creek is a broad belt of 

 limestone, apparently part of the same series. At several 

 places examined this limestone is much metamorphosed by 

 silication, and is intersected by manganiferous and micaceous- 

 iron lode formations. It is in close association with this belt 

 that the hardened breccia, forming Elder Rock and the 

 other outcrops bearing the fertilizer further to the north- 

 east, occurs. 



Owing to its soft character also, denudation has here pro- 

 gressed rapidly and fostered the main drainage lines of 

 the district, developing Grampus Creek and a wide belt of 

 low — at one time, when the rainfall was heavier, evidently 

 swampy — land in its course. 



III. Elder Rock. 



Elder Rock rises from this low-lying level area with 

 almost shear sides 30 ft. in height (see pi. xx., fig. 2). When 

 viewed from a distance it reminds one of a ruined fortress. 

 Its horizontal dimensions are, roughly, 25 yards by 30 yards. 

 A coarse breccia composes a large part of its mass, and ]S 

 usually dark-coloured, due to the presence of much iron, as 

 magnetite and haematite; other parts are formed of ferrugi- 

 nous quartzite. Case-hardening, due to arid conditions, has 

 produced a superficial weather-resisting shell with much softer 

 rock a few feet within. 



On top, in depressed areas, several inches thick of hard 

 yellowish phosphate was discovered. It is likely that at one 

 time this material was more abundant, as traces of it appear 

 over all the top of the rock, and at several places down the 

 sides where showers of ram have transported it in solution. 

 All cracks and fissures were found occupied by the same 

 substance. 



