45 



ridge of argillaceous and hornblendic schists, having a central 

 core of red granite, crossing the county in an E.N.E. direction, 

 Ijut which is covered by at least 70 feet of wind-drifted sandhills. 

 Approaching this exposure the cliff banks are clays and sand- 

 grits, very micaceous, and abounding in gypsum slabs. The flat- 

 topped hills stand back some distance from the channel, as shown 

 in the sketch. Rolled granite boulders occur on top of the dyke 

 and on the schist below, evidently having Ijeen worn by water. 

 The channel is over a quarter-mile wide, and the depth from top' 

 of the sandhill to surface of the sand in the creek is about 125 

 feet by aneroid. The clay bed rests against the schist almost 

 horizontally on either side, and on the up-stream side the water 

 is impounded by the bar of schist, and is the cause of the small 

 holes called Polly's Springs. There is so much salt in the clay, 

 however, that it contaminates the water and renders it almost 

 undrinkable and highly purgative. In the lower part of the schist 

 or near the granite dyke a thin band of argillaceous schist is com- 

 pletely impregnated with almost microscopic specks of green 

 copper ore. An assay of the rock by the Government assayer 

 gave about '18 of a per cent, of copper. The upper portions of 

 the schist are argillaceous and intercalated with narrow bands of 

 brown quartzite, similar to that in the higher beds of the Denison 

 Range at Mount Margaret. 



Thirty miles N.W. of this dyke, over loamy plains dotted with 

 porcelain-capped hills, lead to the bank of the Finke, overlooking 

 old Idracowna station. The cliff banks are of white grit, and 

 from the north side they are surmounted for ten miles by a verit- 

 able sea of steep spinifex-covered sandhills. These abut against 

 and surround a remnant of tableland, which has by sub-aerial 

 influences been cut up into narrow sections of grotesque shape 

 and singular aspect. One of them, which Stuart names Chambers' 

 Pillar, stands on a pedestal of conical outline, composed of thin 

 layers of friable greenish-white sandstone. The pillar is more 

 argillaceous, and the summit for about six feet in depth is stained 

 red by iron, and judging by fragments which are found below, i.s 

 superflcially glazed. 



The two points on the pillar, which in Stuart's description are 

 prominent objects, have in the course of 30 years been weathered 

 to nearly the one level, wherein also the protective influence of 

 the capping portion is attested by the dimensions of the pillar at 

 the summit exceeding its middle girth. Around the north view 

 the broken and detached hills are weathered into castellated shapes. 



Hitherto no section has disclosed what underlies the blue clay 

 bed, but at 14 miles north of the pillar the second division of 

 country begins at Mount Charlotte ridge, the most southerly of 

 the terraced formation. 



