102 PROCEEDINGS OF SECTION C. 



scheelite or axinite. It is not certain how far this silcification of 

 the country is responsible for the formation by replacement of the 

 red jasper bands. 



After this came the great Carboniferous (?) period of granitic 

 intrusion. A large portion of the area studied is underlain by a 

 batholith of micaceous granodiorite, which is exposed in Duncan's 

 Creek on the east and near Mt. Ephraim on the south. Associated 

 with it are a large number of porphyry apophyses, which extend up 

 into the Bowhng Alley and Nundle Series. There is a great variety 

 of these, including quartz, felspar, or hornblende porphyries and 

 granophyi'es. It seems not unreasonable to regard the serpentines, 

 gabbros, diabases and gi'anodiorites as a differentiation series. 



The wide flats on the Peel River, where it bends to the west to 

 meet Hyde's Creek, are composed probably of Permo- Carboniferous 

 rocks overlain by alluvial. Stonier22 reports the occurrence of 

 Glossopteris and other Permo-Carboniferous leaves in a shaft on 

 these fiats, and marine fossils occur by Reichels' homestead on the 

 eastern side. The rock is an arenaceous limestone and contains 

 Deltopeden, Martiniopsis, and obscure casts suggesting Astartila, 

 Edmondia, Mourlonia and Ptycomphalina. This area is doubtless 

 portion of a sheet once continuous over the whole district which has 

 been faulted down into the Devonian beds. 



According to Mr. Andrews, a peneplain was developed in 

 Tertiary times, and, consequent on its elevation, considerable dis- 

 section ensued, and the valleys cut attained considerable size. 2 3 * 

 In this district they had not progressed beyond the canyon stage, 

 when a depression of the area brought about heavy silting. The 

 valleys became filled with coaise gravel, sandstone, and in places 

 soft shales, which contain leaf impressions. Mr. Deane has ex- 

 amined specimens, and reports that the material is very im- 

 perfect. There are fragments suggesting the Cinnamomtm type, 

 Sterculia, Blinder sia, Clerodendron tomentosvtm, Ficus scabra. There 

 are no leaves which can be referred to Eucalyptus. He adds : — 



" I do not think these fossil leaves can lead to any deductions as to 

 age. They are quite of the same character as the Brush vege- 

 tation of our coast, a type which has existed in Eastern Australia 

 from the Miocene, if not from an earlier, period. Of course the 

 climate must have been a much moister one, owing partly to 

 the absence of a parched interior enabling a luxuriant vegetation, 

 now restricted to patches of the coast, to spread over the 

 tableland and down the western slopes." 



The deposits are often of great thickness ; those of Yellow Rock 

 Hill, ne?r Nundle, are 350 feet thick. 



This sedimentation was followed by the outpouring of basic 

 rock, which flooded over the undissected parts of the peneplain, 

 and flowed down the valleys, covering the gravels, etc. Several 

 flows occurred, and between these there are occasionally layers of 

 gravel. While the rocks correspond in the main to the plateau- 

 basalt physiography,^* no evidence has been seen of the fissure 

 eruption, but five distinct necks have been noted. PetrologicaUy 

 these rocks vary considerably ; they include fine and coarse grained 



