30 
The g’eological age of these clolerite intrusions cannot, in the 
light of our present knowledge be fixed with any degree of cer- 
tainty. As regards the prol}lcm connected with the relative age 
of the lavas, ashes, and the dykes and sills, there is but little direct 
evidence: it is pos.sible that they may he grouped together into one 
series, which may be held to represent one distinct phase of the vol- 
canic phenomena of the State. 
Since their deposition the Nullagine beds have been uplifted, 
and are now disposed in a scries of broad anticlinal folds, having 
taken part in orgraphic movements during a period which appears 
to have preceeded the formation of the Permo-Carijoniferous 
strata. The beds were everywhere uplifted by mountain ljuilding 
processes accompanied by folding, faulting, and occasional plication. 
In the Strelley River gorge a section is to be seen which show's the 
sediments and associated volcanic rocks bent up into a sharp anti- 
clinal fold, the axis of which is north-east and south-west. This 
fold is depicted in Fig. 35, but the fold was produced so long 
/ 
Generalised Section along the Strelley River Gorge, 
Kimberley Division. 
ago that its crest has been worn away, and the arch snapped in 
tw'O. I'he dotted lines represent the restoration of this arch. 
Another excellent example of this folding is to be seen in the de- 
nuded auticlinal at Baiigemall, on the Lyons River, the tw^o bands 
of quartzite which form the legs of the fold, rise as conspicuous 
serrated razor-backed ridges, traceable across country for many 
miles. (Fig. 3()). This post-Nullagine movement was doubtless coin- 
cident with similar movements elsewhere in Australia, though at 
present these cannot be definitely correlated. 
