338 



C. A. SUSSMILCH. 



of Devonian age, and extend eastwards along the Oopeland- 

 Gloucester Road to a point about one mile west of the 

 Barrington River Bridge. The whole series is very highly 

 folded, the strata over very large areas being almost ver- 

 tical; their general strike is about N. 40° West. No attempt 

 has been made to study these Devonian strata in great detail; 

 neither the base nor the top of the formation has been found 

 yet in this district; so that it is impossible to give a com- 

 plete section here. The main object in studying these beds 

 has been to attempt to work out their stratigraphical 

 relationship with the succeeding Carboniferous formations. 



I. The Tamworbh Series. — These are extensively 

 developed, around the township of Oopeland and in the 

 railway cuttings between Gloucester and Bundook. They 

 consist of spillite lavas, tuffs, radiolarian cherts, and mud- 

 stones, limestones, and more rarely, quartzites. 



(a) The Spillites. — These do not occur in the immediate 

 neighbourhood of Gloucester but are very extensively 

 developed in the neighbourhood of Bundook. Here they 

 outcrop along the railway line eastwards of Bundook rail- 

 way station for about two miles. The western end of 

 Kangat Mountain (2,000 feet high) is made up entirely of 

 these lavas. They exhibit in places typical " pillow " 

 structure, and are in places somewhat vesicular. Under 

 the microscope they are seen to contain well-preserved 

 pyroxene and albite felspar. These rocks have undergone 

 a considerable amount of alteration in places, with abund- 

 ant introduction of quartz and epidote. Similar spillites 

 of Middle Devonian age have already been described in 

 great detail by Prof. W. N. Benson, 1 from the Tamworth- 

 Nundle District, consequently no detailed petrological 

 description will be given here. 



1 Geology and Petrology of the Great Serpentine Belt, Part III, by 

 W. N. Benson, b.a., b.sc, Proc. Lian. Soc. N S.W., Vol, xxxviii, p. 662, 

 1913. 



