234 ON THE GEOLOGY AND PETROGRAPHY OF BATHURST, N.S.W. 



in a railway cutting. Fig. 2 shows an intrusive vein in Silurian slates, on 

 the outer boundary of the granite, near Newbridge. Fig. 3 is a sketch of 

 forking veins of binary granite, near Newbridge. Fig. 4 shows a younger 

 and lighter- coloured granite penetrating a dark coloured rock of the same 

 character. Figs. 5 and 6 show veins of granite cutting through altered 

 sedimentary rocks. These were sketched in the Winburudale Creek, above 

 the bridge on the Bathurst-Peel Road. Fig. 7 represents junctions between 

 slates and granite. The line of junction is very sharp and well defined, 

 and is exposed in a railway cutting on the Bathurst side of Newbridge 

 railway station. 



Plate xvi. — The highest point of the basalt is about 600 feet above the 

 river. The drift which is shown under the basalt was pierced by a tunnel. 

 The relations of the rocks to the sections are drawn from notes made during 

 the progress of the tunnelling works. Fig. 2 gives the relative positions of 

 all the basalt around Bathurst. Some four miles of the ridges do not 

 show in the sketch, as at the left of the section the chain of hills bends 

 away south at right angles and so is hidden from view. The view is from 

 the north. 



Plate xvii. — Prismatic basalt, Bald Hills. This quarry is very nearly on 

 the line of section marked A B on the map. The weathering of the rock is 

 shown. Large flakes of decomposed matter peel off the sides of the prisms. 

 These flakes are from half an inch to one and a half inches in thickness, 

 and often contain a core of undecomposed basalt. As work goes on it is 

 probable that better columns will be exposed. 



Plate xviii. — Sketch map representing the boundaries of the basalt as 

 accurately as is possible on this scale. It is easy to join the isolated patches 

 and thus trace the former course of the river. 



