BY H. I. JENSEN. 865 



and followed by the elevation of the marine area and the sub- 

 sidence of the continental area westwards. Hence a considerable 

 thickness of coarse conglomerates and boulder-bearing tuffs was 

 formed. At Coolah Station they are over 1,000 feet thick. By 

 the middle of the Permo-Carboniferous period the continental 

 area had been depressed beneath sea-level and sediments began 

 to accumulate there. They are universally of shallow-water, 

 estuarine, and lacustrine origin, comprising sandstone, conglom- 

 erate, grit, Glossopteris shales and coal-seams. No marine fossils 

 have been observed. The grits and sandstones were derived 

 from the denudation of rhyolites and granites which were now 

 undergoing weathering in the elevated regions to the north and 

 east. There is a distinct unconformity between Permo-Carbon- 

 iferous and Carboniferous beds at Maule's Creek. Those of 

 Carboniferous age are more highly folded, often faulted, and 

 have interbedded igneous rocks derived from contemporaneous 

 volcanic action. 



Trias-Jura sedimentation followed Permo-Carboniferous. Sub- 

 sequent to this came the folding of the deposits, from the 

 S.S.W,, against the New England massive. Elevation took place. 

 The uplift was probably contemporaneous with one in New 

 England which preceded the Mole Cycle. "^ The uplift in the 

 Nandewar region probably gave rise to a gentle fold running 

 N.N.W.-S.S.E. locating the mountain axis. Laccolitic injections 

 of basic rock (olivine dolerite, etc.) took place at the same time 

 (probably Cretaceous). Base-levelling to the level of the western 

 Cretaceous sea left a peneplain with a gentle slope to the west; 

 its level in the Nandewar Mountains is marked by the flat- 

 topped sandstone mesas averaging about 1,400 feet in altitude. 



Further earth -movements of late Cretaceous or more probably 

 of early Tertiary age, coincident with the Tertiary elevation of 

 New England (introducing the Stannifer Cycle) in which Bingera 

 and Barraba districts shared, seem to have given rise to a fault. 



* Andrews, 'Tertiary History of New England,' Records Geol, Surv. 

 N. S.Wales, Vol.vii. 



