92 



E. 0. Teale 



fragments and boulders. Some of these are exactly similar to the 

 rhyolites and rhyolitic porphyries of the Wellintjton series which, 

 overlie these beds. Others are too decomposed for definite com- 

 parison. 



No outcrop of Lower Devonian igneous rock has been recognised 

 in the area, but as indicated previously rocks probably of this age 

 occur about ten miles to the N.N.W. at Fullarton's Spur and 

 about forty miles to the N.N.W. in the King River District. 



From a comparative microscopic examination of numerous thin 

 sections of Lower Devonian povjihyries with those from the Welling- 

 ton area, the details of which will be given later, it appears prob- 

 able that a satisfactory distinction may l)e made m,icroscopically 

 between the two series. 



If this feature is proved by wider investigation to enable a 

 generalisation to be made, it may be possible to recognise in these 

 conglomerates and breccias, porphyries of two distinct periods re- 

 presenting material derived from a Lower Devonian source, and 

 also later rocks belonging to the first products of the outbreak of 

 the Lower Carboniferous volcanic activity. 



A considerable thickness of acid lavas and tuffs succeeds these 

 basal l>eds over wide areas, and it seems likely that though the main 

 outburst and effusion slightly succeeded the deposition of the- 

 conglomerates, some of the earliest outbursts were practically con- 

 temporaneous, contributing some of the admixed igneous material 

 Avhich suggests the nature of volcanic ejectamenta. 





Section 3 10 



Roan Horse Gully 



One of the best sections showing the basal beds where the- 

 breccia character predominates is at Locality G, Wellington- 

 River, about three-quarters of a mile below the Wellington-Dolo- 

 drook junction. The beds are of a coarse nature, and contain 

 both angular and water-worn rocks, consisting largely of black 



