144 ENOGGERA GRANITE AND ALLIED INTRTJSIVES. 



diverge that the Enoggera Reservoir is constructed. From 

 both Taylor Range and Enoggera Range spurs are sent 

 out to the east, north-east, and south-east, but these soon 

 merge into rounded and semi-isolated hills. Further away 

 to the east, north and south these in their turn gradually 

 fade into gently-undulating country. This topographical 

 sequence from steep ridges to rounded spurs and foot-hills, to 

 undvilating plain can easily be interpreted in terms of the 

 varying resistance to erosion of the different rock 

 formations met with. The granites, and the schists 

 where they have been reinforced by intrusions, weather 

 into steep ridges which, though occasionally precipit- 

 ous, generally present rather rounded profiles. This 

 description applies equally well to both these rock types 

 since their modes of weathering are so similar that, from 

 a consideration of topography alone, it would be well nigh 

 impossible to tell, when looking from a distance on, saj', 

 Taylor Range, where the granite ended and the schist began. 



The schists, on the other hand, which have not been 

 strengthened by intrusions are shaped by erosion into semi- 

 detached rounded hills. 



The undulating plains which — though they do not occur 

 within the area mapped — succeed these hills of schists, are 

 the result of weathering of the Trias -Jura sediments. 

 The Tertiarj^ gravels where met with form sub-horizontal 

 outcrops, while the recent alluviums are found as typical 

 river flood -plains. 



These different modes of weathering are reflected in 

 the courses of such streams as Cubberla Creek, which, 

 rising in a miniature gorge in the heart of the Taylor Range, 

 flows rapidly through its narrow channels into the foot-hills,^ 

 among which it winds its way in a more leisureh' manner, 

 coming at last to the recent alluvium, through which it 

 wanders in typical meandrine fashion before it finally 

 flows sluggishly into the Brisbane River. Another, and 

 perhaps better, example is instanced in Ithaca Creek. 



The question has been raised as to whether the Taylor 

 and Enoggera Ranges are to be explained as residuals, or 

 as the result of faulting. Cameron^ has suggested that 



1. W. E. Cameron, Oc. Cit. d. 3. 



