nv W. X. BENSON, W. S. DuN, AND W. R. BROWNE. 309 



ditious from those when the Buriudi mudstones were deposited in a sea some 

 distance from land, to those during the formation of Kuttung times, when in the 

 vicinity of this area appeared high land from which glaciers carried a load of 

 granitic erratics, and streams discharged abundant more or less rounded boulders, 

 nud land plants flourished. As Professor David and Mr. Sussmilch _have pointed 

 out (4), though this movement did not produce a stratigi-aphieal unconformity, it 

 was one of great importance, and with it there occurred immense and prolongea 

 explosive volcanic activity yielding- the felspathic tuft's. These are clearly related 

 to the keratophyres in the Werrie Series. It requires more detailed survey than 

 has been possible as yet to determine whether the Werrie Series lies conformably 

 upon the Kuttung sediments, or whether some crust movement and erosion of the 

 Kuttung rocks preceded the outpouring of the basalts, probably through fissures 

 radiating from volcanic centres. It is evident, however, that no gTeat hiatus 

 occurred. The intrusion of pyroxene andesite may have occurred sometime be- 

 fore the outpouring of the basalts. Crust-fracturing and extensive faulting 

 supervened, and especially at this period would we note the formation of the 

 Cun-abubula Creek zone of fractures, into which were injected felsitic magmas 

 (keratophyres and perhaps the hornblende andesites) of much the same composi- 

 tion as the pre-basaltic tuffs. The magma rising in fault fissures also was thrust 

 out into sills (see p. 305). 



Perhaps also at this period were formed the large intrusions of quartz 

 keratophyre on Upper Currabubula Creek, Werrie's Creek, and west of Curra- 

 bubula township. The age of the porphyrites and dolerites we do not yet know, 

 but among the latest extrusions must be placed the basalt dykes, now largely de- 

 composed, and as these occur so frequently in the fissures of powerful faults, it is 

 probable that crust movements were still in progTess at the time of their intrusion. 

 We have thus evidence of long, but not necessarily unbroken succession of igneous 

 events accompanied by crust-movement. 



No evidence of the extension of these dykes of felsite, dolerite or basalt into 

 the Glossopteris sandstone has yet been found, and therefore we conclude that the 

 igneous activity about the Warragundi centre had ceased before their formation, 

 though the crust movements had not then ceased. Thus, in the presence of ex- 

 tensive igneous activity extending from the Carboniferous period possibly into 

 Permian time, with cnistal instability of even longer duration, we find some 

 analogy here with the sequence of events in the Hunter River District (4). 



PHrsiofiRAPHV OF THE Peel River Vallet and its Bordering Ranoes. 



In this section we discuss first the detailed physiography of the Currabubula 

 district as an introduction to a general consideration of the valley of the Peel 

 River. The special interest of the physiography of the Currabubula district lies 

 in the vivid manner in which it illustrates the effects of differential erosion of a 

 complex terrane. The western portion of our area is formed of the wide lowland 

 of the Tamworth Plains; the portion west of the Werris Creek and Piallaway 

 Gaps is similarly portion of the Liverpool Plains, both of which lowlands ai-e 

 (near our area) cut from the soft Burindi mudstones. The broad valleys of 

 Turi and Sandy Creeks are cut from the soft felspathic tuffs comprising tlie 

 lowest portion of the Kuttung Series, while the lowland basin between Curra- 

 bubula, Werrie's and Qui|ioIly Creeks is cut from decomposed basalts. These sur- 

 faces lie between 1200 and 1400 feet above sea level. The elevations are all of 



