548 Harry Page Woodward — Geology of Western Australia. 



Paleozoic. 



The Carboniferous formation is largely developed in the Kimberley 

 district, forming flat-topped hills and ranges which consist mostly 

 of shale with quartzite cappings ; there are also a few limestone 

 beds. A small patch of the Upper Carboniferous formation has 

 been discovered upon the Collie Eivei', consisting of shales, sand- 

 stones, fireclays, with coal-seams. It is probably one of a series 

 of small basins lying to the eastward of the range, but as the 

 whole surface is covered by recent formations, this remains to be 

 proved. The Lower Carboniferous outcrops upon the Irwin River, 

 where there are a series of shales, fireclays, sandstones, and lime- 

 stones, with coal-seams. This formation extends north in a narrow 

 strip to the Lyons River. 



The Devonian formation has only been certainly proved to exist 

 in the Kimberley district, where there is an almost horizontally 

 bedded series of sandstones, grits, conglomerates, shales, and lime- 

 stones, which contain fossils ; but on both sides of the Ashburton 

 River there is a great extent of magnesian limestone, which probably 

 also belongs to this age. 



The Silurian rocks have only been identified in the Kimberley 

 district, but they are probably represented in other parts of the 

 colony by clay-slates and quartzites, as in the Stirling Range. 



The Cambrian formation has also been proved to exist in the 

 Kimberley district, where it contains the gold-bearing lodes. 



Azoic, OR Arch^an. 



The ArcJicean and Crystalline rocks are more largely developed in 

 this colony than in any other portion of the world, outcropping as 

 they do in all parts of the country, and, where they are overlain by 

 more modern formations, these latter are rarely of any great thickness. 

 This series is highly contorted, being folded into a number of 

 parallel anticlinal and synclinal folds, striking north and south, and 

 often presenting the appearance of a highly inclined dip, which is 

 either nearly vertical, or trending slightly to the eastward. These 

 rocks are much broken and faulted by numerous diorite and granite 

 dykes; they contain many quartz-veins and iron lodes, and it is in 

 this group of rocks that the principal auriferous deposits exist. 



This great series of rocks may be subdivided into three sections, 

 which, as a rule, run in parallel belts north and south, with a 

 slight trend to the north-west in the northern part of the colony. 



The first, or western, belt extends from the Murchison River to 

 the south coast, but is very little exposed, except in the Northampton 

 district, and a little south of the Irwin River, where it is rich in 

 copper, lead, and zinc ores. It underlies the sandy coastal plains, 

 outcropping here and there at the base of the Darling Range, 

 forming a small range between the Capes Naturaliste and Leeuwin, 

 and characterised throughout by lead, copper, and zinc lodes. The 

 rocks of this belt are, for the most part, comparatively soft, con- 

 sisting of clay-slates (often kaolinised), quartzites, and schists, with 



