BY W. X. BENSON. 341 



at other times, giving more or less definite igneous zones, l)ut 

 stratigraphica] correlation on tlie petrological features of pyro- 

 clastic rocks alone is exceedingly unsafe. It is quite possible 

 that the Pyramid Hill tuff belongs to a period of eruption rather 

 more recent than that of the Baldwin Agglomerates, and that 

 the true horizon of the base of the Barraba Series lies at some 

 indefinite horizon between the Loomberah limestones and the 

 Pyramid Hill tufi". As the outbreak of the huge eruptions, 

 which formed the Baldwin Agglomerate of the Manilla-Bingera 

 region, might reasonably be expected to have been associated 

 with some crust-movement in adjacent districts, we may put 

 forward the suggestion that the Scrub Mountain conglomerate 

 (the lithology of which seems to point to the occurrence of some 

 crust-movement) might be considered contemporaneous with the 

 Baldwin Agglomerates. This hypothesis has the merit of in- 

 volving a less radical change than the former one in the con- 

 ception of the range of characters of the Upper Middle Devonian 

 rocks, and is, therefore, adopted in the map. But it cannot be 

 considered as more than tentative, lacking as yet confirmatorv 

 evidence. On this hypothesis, the portions of the Nundle Series 

 lying south-west of Nundle Sugarloaf and Yellow Bock Hill (3, 

 Plate xxii.) belong to the Harraba Series. 



The Devonian Igneous Rocks. 

 Igneous Bocks in the Eastern Series. — The igneous rocks in 

 the Eastern Series must be first briefiy discussed, before passing 

 on to the more important rocks west of the serpentine. They 

 consist, for the most p^irt, of bands of more or less schistose 

 breccias and agglomerates, which are fairly abundant, and are 

 particularly well seen in a zone which runs nearly due north 

 from the western end of Portion 42, Loomberah, to the eastern 

 end of Portion 46; while less noteworthy masses occur, east of 

 the Peel River, in the Parishes of Gill and Nemingha. Massi^e 

 igneous rocks have a more restricted occurrence. Spilites are 

 found a mile north of Dungowan Hotel in Portion 52, Gill. 

 Vesicular keratophyre occurs near by in Portion 51, and in Por- 

 tion 43 of the Parish of Loomberah is a very small lenticle of a 



