BY W. N. BENSON. 233 



No graphite-flakes were observed, such as are commonly present 

 in the Hawkesbiirv 8andstone. To the east, the sandstones 

 ho on the eroded surface of the granites, from wliich they were 

 in large measure derived. To the south-east, they are overlain 

 by basalts. (See Plate xix.). 



The boundary of the granites M'hich form the eastern margin 

 of the Eastern Series was, in part, based upon information 

 obtained from the State Geological Survey, in part from obser- 

 vations of Mr. D. Porter and others. The writer has studied 

 these granites near the Namoi River only. 



ii. The Serpentine Line. 



This has been defined as the well marked line of fault which 

 separates the Eastern Series from the formations to the west, 

 and is generally occupied by a band of serpentine of varying 

 width. No serpentine occurs on the Namoi River, but a narrow 

 strip may be seen two miles to the north. Eight miles north of 

 the river, it occurs again, and may be traced thence up a branch 

 of Yellow Rock Creek. In Portion 42, Parish of Welsh, there 

 occurs, within the serpentine, an oval patch, about forty feet long 

 and twenty feet wide, of a peculiar rock containing, in a white 

 granular matrix of clinozoisite and zoisite, muscovite and oligo- 

 clase, long green masses of chlorite-spherulites that are probably 

 pseudomorphous after hornblende or augite. Possibly this is a 

 highly altered gabbro-pegmatite. (See 1, Pt. iii., pp. 7 2 1-2). 



North of this, there are massive and schistose serpentines, 

 with small patches of enstatite-rock and anorthosite. The western 

 side of the serpentine is transformed into a mixture of siliceous 

 sinter, magnesite and siderite with more or less haematite, which 

 will be given the very useful miners' term, "serpentine-gossan," 

 in succeeding parts of this paper. It has often a marked relief. 



Between Yellow Rock Creek and Crow Mountain, the land- 

 surface is almost flat, and the serpentine is not clearly developed. 

 Its place is taken by a little serpentine-gossan, and there are 

 also small dykes of dolerite of a type which generally occurs 

 with serpentine in the northern portion of the Serpentine Belt. 

 (See 1, Pt. iii., pp. 688-9). They are particularly abundant in the 



