Sarry Page Woodward — Geology of Western Australia. 549 



dykes of diorite and granite, and veins of quartz and pyrites, con- 

 taining lead, coppei', zinc, iron, and ferruginous graphite. 



The second belt extends northward from the south coast (forming 

 the bold escarpment at the edge of the great plateau called the 

 Darling Range) as far as the Murchison Kiver. It then follows 

 this river in a narrow belt in a north-easterly direction for about 

 200 miles, where it suddenly spreads out to the east and north-west 

 from the Robinson Range to the Lyons River, disappearing beneath 

 the magnesian limestones to the northward. 



In this belt the rocks are mostly hard and crystalline, consisting 

 principally of gneiss and schist, with dykes of diorite, granite, and 

 telstone, and veins of quartz. The latter (as well as the diorite) 

 often contains large quantities of pyrites, most of which jneld a 

 little gold. Tin is also being worked at the Green Bushes Tin-field, 

 the ore being derived from the disintegration of quartz-porphyry 

 dj^kes, in which it is associated with tourmaline and titanic iron. 

 Besides iron and manganese, large deposits of kaolin of a very fine 

 quality occur, as well as veins containing mica and asbestos ; but 

 these latter are too much weathered at their outcrop to be of any 

 value. 



Near Bridge town a very large deposit of graphite has lately been 

 opened up: it exists in the form of a bed between talcose schists 

 about 20 feet in thickness. 



The third or great granite belt lies about 100 miles east from the 

 west coast, and is about 100 miles in width, extending from the 

 south coast to the Murchison River. It consists of a series of bold 

 bare outcrops of gneiss or granite often 100 feet in height and 

 covering several hundred acres in extent, rising from loamy flats. 

 The rocks mostly outcrop in the depressions of the table-land, the 

 higher portions of which are covered by sand-plains. This belt is 

 absolutely destitute of mineral veins, and it is due to this barrier 

 that the rich gold-fields to the eastward remained so long un- 

 prospected. These outcrops are made use of for the conservation of 

 water in this dry portion of the colony, as they shed water like a 

 house-roof, whilst around them there are many natural dams or 

 basins filled with sand, which are either being cleaned out or wells are 

 being sunk in them. The rocks of this belt consist entirely of gneiss 

 and granite, much fissured and faulted, and traversed by numerous 

 dykes of granite and diorite, whilst the main masses generally 

 enclose fragments and masses of schistose and gneissic rock. 



The fourth or first auriferous belt is situated immediately to the 

 eastward of the granite belt, and is about 20 miles in width. It 

 starts from the south coast at the Phillips River, extending north- 

 ward in a narrow belt by the Ravensthoipe Range, Parker's Range, 

 Southern Cross, Golden Valley, Mt. Jackson, Mt. Kenneth, Mt. 

 Magnet, Austin's Lake to the Cue. Thence it takes a slight bend 

 to the north-east to Nannine and the Star of the East, where it strikes 

 more to the north, and skirting round the heads of the Murchison 

 and Gascoyne Rivers, it turns north-west and follows down the 

 Ashburton Valley to its junction with the Henry, finally dis- 



