BY THE REV. J. MILNE CURRAN. 195 



of contact metamorphism can 09 followed in a line clue north 

 from Mr. Coombe's residence, Glanmire. Spotted schists and 

 hornfels can be followed by travelling up the creek (a tributary of 

 the Winburndale) from the culvert referred to on p. 192. The 

 hornfels will be found exposed between the head of the creek and 

 the road. Hornfels rock, in many interesting varieties, can be 

 collected too at Duramana, where it is used for road purposes. Good 

 outcrops of the same rock are easily accessible in a road cutting 

 on the Orange Road, near the " Rocks," as well as on the Rockley 

 Road, south of Perth, and on the Blayney Road, near the granite 

 boundary. 



The aureole of metamorphic rock around the granite may be 

 divided into three zones, but, from the very nature of the case, it 

 is evident that no hard and fast line can be drawn between these 

 belts. The zones may be distinguished as — 



1. Zone of micaceous clay slate. 



2. Zone of knotted slate, often mica slate (Knotenglimmer- 



schiefer). 



3. Zone of hornfels rock. 



It will of course be understood that these zones of rock do not 

 follow each other in due succession at every point. That this 

 should be so would suppose denudation to have excavated the 

 river valley equally on all sides — a manifest impossibility. As a 

 matter of fact knotted and altered slates may be found at times 

 nearer the central granite mass than hornfels rock. But this 

 difficulty is easily explained by assuming an underlying mass of 

 granite not yet exposed, or by noticing that sometimes the granite 

 dips away under the slate rock at a low angle and further on 

 comes once more to the surface. 



Relative Age of the Sedimentary Rocks. — Silurian slate is the 

 oldest rock around Bathurst. At first sight this may seem rather 

 puzzling. The position and structure of these slates show them to 

 be sedimentary in origin. But we have abundant proof that they 

 were laid down, consolidated, and crushed into great folds long 

 before the granite was erupted. Of course we might suppose the 



