324 GREAT SERPENTINE BELT OF NEW SOUTH WALES, vii., 



rises up into a peneplain-surface of about 3,500 feet in height, 

 cut in hard rocks, chiefly siliceous phyllites, and very much dis- 

 sected by deep valleys, some following the structure of the 

 country, others oblique thereto. West of the river, the topo- 

 graphy is more complex. The geological formations are arranged 

 in parallel zones of resistant and less resistant rocks, so that 

 there is a succession of ridges, the ridge of the Eastern series 

 directly west of the Peel River, running north from Wallaby 

 Mountain by Woolomin, composed chiefly of siliceous phyllites 

 and jasper, the ridge of tuffs associated with the Loomberah 

 limestone, and the ridge of tuffs and agglomerates which form 

 the Pyramid Hill Range. To the south, a fourth ridge of con- 

 glomerate intervenes between the last two. These ridges are 

 separated by the open valleys of Sandy Creek and Reedy Creek 

 respectively. To the south of these creeks, there is a series of 

 more youthful streams, which cut athwart the grain of the country, 

 and flow generally north easterly or east-north-easterly into the 

 Peel River. Of these. Cope's Creek is the most important. The 

 lower portion of the creek is thus roughly parallel to the series 

 of dip-faults (see p. 360) which cut through the country and may 

 originally have been determined b}^ one of these. Pipeclay 

 Creek, Silver Gully, and Hyde's Creek belong to the same trans- 

 verse system of streams. The same holds even more clearly for 

 the creek north and west of Wallaby Mountain. 



General Geology. 



To understand the significance of the features observed in 

 this district, those to the south and north must be reviewed. 

 Along a line of section drawn westwards from the serpentine 

 near Bowling Alley Point, the following sequence was observed 

 {see 3): — 



i. The Lower Banded Radiolarian Claystones. 



ii. The Lower Bowling Alley Tuffs and Breccias, in which 

 there are numerous intrusions of dolerite and spilite. 



iii. The Limestone. 



iv. The Upper Banded Radiolarian Claystone, interstratified 

 with a large amount of tuff and breccia, and abundant intrusions 

 of spiiite and dolerite. 



