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imagined ; it must be seen to be fully understood. Not only has 

 the pressure produced foldings of great regularity, but now that 

 many of the anticlines are partially denuded it would be difficult 

 to conceive of strata more evenly and beautifully formed. It is 

 the rule, in fact, where the strata stand at all vertical to find high 

 parallel wall-like ranges reaching for miles, sometimes for scores 

 of miles, through, across, or over which the traveller cannot go. 

 It is possible to ride the whole length of the ranges between 

 walls of rock that tower up perpendicularly on either side, and 

 meditate on the time when the narrow plain through which he 

 rides was once filled with limestones, shales, or other rock equally 

 fragile in comparison Avith quartzite. This description applies 

 wherever the strata are sufficiently vertical, and no newer forma- 

 tion overlies and fills the denuded space. 



The folding is traceable to the south and east until covered by 

 Cretaceous and Tertiary formations. The first synclinal forms 

 the valley now called the Missionaries' Plain ; it runs from Gar- 

 diner's Range to the Hale River. Looking from this plain to 

 the northward the MacDonnell Ranges South rises almost verti- 

 cally a thousand feet out of the plain; it has a few foothills, 

 which will be noted hereafter, and designated " Pudding-stone 

 Hills." They attain to, if not over, 3,000 feet above sea-level, 

 and all the ranges of crystalline rocks lying behind and to the 

 north of it are hidden from view. Only a few peaks and tops of 

 the highest ridges as they rise a thousand feet higher can be seen. 

 It is thought that many of the highest peaks of the MacDonnell 

 exceed 4,000 feet above the sea, but if I am not mistaken Mount 

 Giles will be found to be the hisjhest elevation. There are four 

 passes through the MacDonnell Ranges South in a distance of 

 150 miles, viz.. Temple Bar, Ellery's Creek, Finke Gorge, and 

 Mareena Bluff", the latter being near the western end. At the 

 three first-mentioned the strata stand nearly vertical, but in the 

 latter inclined to the south, and some 20 miles has to be travelled 

 before the five miles of range in a direct line north and south can 

 be crossed. Travelling northwards through the pass a wide 

 valley is entered. On the western side a horse could walk up the 

 incline to the top of the nearest cliff; to the east towers up a 

 bold headland a thousand feet high at least. The view from near 

 the entrance to the pass is graphically described by Mr. Ernest 

 Giles, F.R.G.S.* The track leads under receding blufis on the 

 right ; the valley gradually closes through the strata becoming 

 more vertical, and evexitually a way is found to the north through 

 a creek-gorge by which the pre-Silurian limestones are reached. 

 Apart from the grandeur of the pass, the strata at this place are 



* "Geographic Travels in Central Australia," 1875, p. 22. 



