PRESIDENTIAL ADDRESS. 13 



little doubt that both overfolding and overthrusting are 

 present. 



Fig. 4. Sketch roughly diagrammatic Prom Perth to Kalgoorlie. 



^ Suggested b^obsecyiationsof A Gibb-Maitland,FG3 



,'s~ -. ^ '---.'" _-.\'~- \ „--'-.$ = 



_. .. v ~' Southern Cross jH? V8 ''~, ,: F-- 



Perth DARLI NG RANGE \1 ' P ENEPLAIN ffg ;Q/ ,'// 



/jI^^/gm/ss/^^^GNEISS^^^ ^GNEISS / 

 < ' 390 miles ■ >■ 



As the Pilbara region is approached, all the trend lines, 

 as shown on Plate 2, swing from, the nearly meridional 

 once more into a N.'W. and S.E. direction. This trend is 

 well shown in the directions of the Ashburton, Fortescue, 

 and De Grey Rivers, as well as in the trend of ranges like 

 the Hammerley Range and the Throssell Range. 



The Doolena Gorge, "the gateway of the north-west," 

 and the Bangemall Anticline both have a N.W. to S.E. 

 trend. The S.W. limb of this large anticline is steeper than 

 the N.B. line, which suggests that the overfolding in this 

 case came from the N.E. The fold 'pitches' to the S.E. r 

 which suggests that the earth-movement was more intense 

 towards the N.W. At Warrawoona the newer dolerite 

 dykes intersect the older folded rocks in enormous numbers. 

 Their dominant strike is from S.W. to N.E., as in the case 

 of the Northam dykes. 



In the Kimberley district of West Australia, Mr. E. T. 

 Hardman^ias described Pre-Oambrian, Cambrian, Devonian 

 and Carboniferous Rocks. Mr. H. P. Woodward 2 has also 

 described part of this area, as well as Dr. R. L. Jack, ll.d., 

 f.g.s. 3 Their observations show that the schists, gneisses, 



1 Eeport on the Geology of the Kimberley District, by E. T. Hardman 

 By authority, Perth, 1884. 



2 Report on the Gold-fields of the Kimberley District, by H. P. Wood- 

 ward. By authority, Perth, 1891. 



3 Bull. Geol. Survey, West Australia, No. 25, pp. 1 -46. 



