20 T. W. E. DAVID. 



The great spiral commences in Kangaroo Island where an 

 east and west trend swings gradually into a N. by E. to 

 N.N.E. direction through the Mount Lofty Ranges, with a 

 fine series of overfolds directed towards the west. As the 

 Barrier Ranges are approached, the trend lines virgate 

 striking about E.N.E. (true) near Broken Hill. There the 

 folds are overturned and the fault planes overthrust 

 towards the S.S.E. Thus the ' sense ' of the folding changes 

 in the country which intervenes between the Mount Lofty 

 Ranges and the Barrier Ranges. Mr. Howchin has shown 

 that in the region which lies between the Barrier Ranges 

 and Lake Torrens, the Flinders Ranges are not folded 

 asymmetrically. Mr. Howchin 1 has shown that in the 

 northern section of the Flinders region the trend lines, near 

 Beltana, strike N.W. Mr. H. Basedow also states 2 (p. 81) 

 that the Cambrian strata near the head (northern end) of 

 Lake Torrens appear to strike from N. 25° W. round to W. 

 This suggests that the old trend lines of the western part 

 of the great virgation are swinging round to meet the 

 trend lines of the Musgrave Ranges. 



These ranges described by Gosse, 3 1873, and by H. Y. L. 

 Brown 4 and V. Streich 5 have also been examined and 

 reported upon by Mr. H. Basedow, 2 who shows that these 

 Pre-Oambrian ranges formed of gneiss, schist, granite, 

 quartzite etc., have a dominant strike nearly E. and W. 

 At Opparinna Spring he figures a strong overfold directed 

 to the north. In the Kelly Hills the schists strike about 



1 The Geography of South Australia, Whitcombe and Tombs, 1909, p. 90. 



3 Trans, and Proc. Roy. Soc. S.A., Vol. xxix, 1905, Geol. Rep. on the 

 country traversed by the S.A. Gov. N.W. Prospecting Exp. 1903, pp. 57 - 

 103, pis. xiii - xx. 



3 Gosse, Central and Western Exploring Expedition. By authority, 

 Adelaide, 1873. 



4 Rep. Journey from Warrina to Musgrave Ranges, p. 2, Adelaide. By 

 authority, 1889. 



5 Sci. Results Elder Expi. Exp., Trans, and Proc. Roy. Soc. S.A., Vol. 

 xvi, pp. 77 and 83. 



