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Jurassic ( ?), were laid down, for that formation is seen to 

 occupy the eroded spaces. Subsequent erosion has almost 

 completely removed the Jurassic ( 1) rocks from the highlands, 

 sporadic remnants only remaining, affording evidence of the 

 former dimensions of the formation. The remnants owe their 

 existence, in the majority of cases, to hard cappings of 

 quartzite, etc. When the Jurassic ( ?) strata were laid down 

 the orographic features of the present Central Australian 

 region, in a general way, were much the same as we find 

 them to-day, subject, of course, to subsequent denudation. 

 Erosion has now laid bare the older rocks on which the 

 Jurassic ( ?) reposed, and to some extent cut deeper into them. 



The writer is of opinion that the Jurassic ( ?) formation 

 was the last continuous formation laid down in that part of 

 the continent. Many of the hills hitherto classed as Tertiary, 

 and most of the so-called Tertiary cappings and outliers in 

 and around the Central Australian ranges and north of Mount 

 Daniel, have no existence as such. They belong to this 

 Jurassic ( ?) formation. Chambers Pillar is a typical example. 

 The last submergence beneath the sea was in Cretaceous times, 

 and for this reason Tertiary strata, as a continuous formation, 

 never existed there. A little rearranged material may form 

 the tops of some of the flat-topped hills within the area under 

 notice, which is often permeated with secondary silica, oxide 

 of iron, etc., forming an enduring crust. No fossils have yet 

 been found in this formation. Like the Cretaceous, this 

 formation is seen to have undergone considerable erosion. 

 Before erosion set in the formation was continuous through- 

 out the ranges; it about half filled the valleys, and the older 

 rocks stood out from it like islands above the sea. 



What movement has taken place in the ranges since the 

 Jurassic ( ?) was laid down is impossible to say, but the 

 slightly-inclined strata in the low hills occurring on the south 

 side of the MacDonnell, east of Emily Gap, may or may not 

 have been due to earth movements. Probably the old anti- 

 clinal and synclinal folds have gradually yielded to pressure 

 since the Jurassic ( ?) strata were formed. Between Idracowra 

 and Horseshoe Bend is a long, low . anticline ; and six miles 

 north of Crown Point evidences of earth movements are clearly 

 apparent. At Horseshoe Bend, right where the station 

 stands, the rocks are faulted. From these features it is evi- 

 dent some earth movement has transpired since the beds were 

 laid down. They are unconformable to the rocks on which 

 they repose, but whether discordance occurs between them 

 and the Cretaceous shales is unknown. The evidence afforded 

 by the artesian bores south of Goyder Well leans in that 

 direction. 



