178 



GEOLOGY AXD PETROGRAPHY OP CLAEENCETOWX-PATERSON DISTRICT, : 



interstitial material has not yet been finally determined. Following these rocks 

 is a fine-grained tuff, which in hand-specimen reminds one of a normal basalt. 

 It is made up almost entirely of tiny angular fragments of quartz and sub- 

 ordinate felspar set in an unresolvable groundmass. Upon this tuff lie the 

 daeitic rocks and the soda-rhyolites. 



East of the Railway Line and the Martin's Creek fault, there is an in- 

 teresting area of Volcanic Stage outcrops. Here and there local types of tuffs 

 and lava occur, and it would be almost impossible to incorporate the details of 

 all these occurrences in a general section, but the most inclusive traverse is that 

 along the line L-M on the map, description of which is given below {see Text-fig. 

 5). 



Starting a chain or two to the north of the point where Martin's Ci'eek flows 

 under the Eailway line, east of the Martin's Creek fault, one passes im- 

 mediately on to the decomposed outcrop of the quartz-keratophyre flow, which 

 trends east up the valley of Martin's Creek. Then crossing into portion 25, 

 Parish of Barford, a coarse tuffaceous conglomerate is found. In this paddock 

 some very large boulders occur, quite a number exceeding three feet in dia- 



Text-fig. 5. The Martin's Creek Section. (Line L-M on map 



meter. These conglomerates are continued in the cuttings of the Railway, and 

 just at the first overhead bridge south of Martin's Creek the chief features of 

 these rocks can be examined. Current bedding occurs among the tuff bands, and 

 there are rapid changes in the average size of the pebbles in various bands. 

 Towards the top of the mass the tuffs are very much weathered, and they end 

 under a flow of potash-rhyolite, which is veiy restricted in extent, the only 

 other place of outcrop being at Mt. Gilmore. This is succeeded by the equivalent 

 of the soda-felsite occurring near the Gostwick Bridge, forming flow No. 4 in 

 the section described by Sussmilch. The rock here is well developed and forms 

 a bare hill to the east, no further extension being observed. It is overlain by 

 the toscanite (Mt. Gilmore type), which in the account of the Regional Geology 

 is shown to be very widespread and important. There is an abundance of large 

 quartz crystals with subordinate orthoclase and plagioclase in a base which has 

 a very rough feel. Following this there is a group of tuft's and conglomerates 

 including the flow-breccia type, already sufficiently described. The final rock 

 of the Volcanic Stage is a daeitic type, the extension of which, to the east, is 

 singiilar on account of some remarkable inclusions made up entirely of spheru- 



