president's address — SECTION c. 135 



amygdaloid, and, although most of their original characters have been 

 almost entirely obliterated, there seems every reason to believe them 

 to be ancient lava flows which were poured out at practically the same 

 geological period as the associated sediments. In addition to these 

 undoubted lava flows, there are a series of diorites and epidiorites, 

 which seem to be interbedded with the former in such a way as to 

 suggest the possibility of their being intrusive sills and dykes. These 

 igneous rocks have been subjected to considerable dynamical altera- 

 tion, and in places appear as mica and chlorite schists. 



Another very important feature in the geological structure of 

 Norseman is the occurrence of a large number of quartz porphyry 

 dykes, which traverse the eastern portion of the field in a general 

 north-west and south-east direction. These acidic dykes vary much 

 in appearance, color, and texture, the crystallisation in some cases 

 being such that the rocks look not unlike somewhat fine-grained in- 

 durated sandstone. These acidic dykes contain crystals of pyrites, 

 and are occasionally slightly auriferous. These dykes in all probability 

 form the apophyses of that large granite mass which lies to the east of 

 Norseman. There are, in addition, a few isolated veins and dykes of 

 dolerite, one of which is seen intersecting the quartz reef in one of the 

 mines. The newest igneous rock on the field is the intrusive norite, 

 which forms an east and west range, varying from a mile to half a mile 

 wide, and which extends in an uninterrupted line to Mount Norcott, 

 about 12 miles to the east, and for a considerable distance both east 

 and west. 



The earliest observer in this district, Mr. S. Goczel, indicates 

 on his Geological Sketch Map of the Auriferous Region of Western Aus- 

 tralia, the greenstones and allies of Norseman as being of Palaeozoic 

 Age, whilst the micaceous and talcose schists of the same district are 

 referred to the Archeean. 



The crystalline rocks of the type just described may be traced as 

 far as the Kalgoorlie Goldfiekl, the wealth of which — coupled with the 

 skill which directs both the mining and the metallurgical operatioiis — 

 has raised Western Australia to the front rank of mining countries 

 in the British Empire. 



As is well-known, the productive area comprises a relatively small 

 block of ground, which, by reason of the richness of the lodes by which 

 it is riddled, has become known throughout the world as " The Golden 

 Mile." This area includes the well-known " Great Boulder," " Ivan- 

 hoe," " Horseshoe," " Perseverance," " Oroya-Brownhill," " Associ- 

 ated," and " Lake View Consols " mines. The deepest shaft at present 

 is the Great Boulder, which has reached 2,050ft., while the greatest 

 depth to which the lodes have been followed is over 2,000ft. The 

 country laid open by mining for investigation, as judged by the number 

 of drives and crosscuts, amounts to several miles, whilst the rocks 

 have been riddled with bore-holes in all directions and at all angles, 

 thus affording opportunities for the scientific study of many of the 

 rocks in critical localities, and in their relation to the ore deposits, 

 such as are hardly found in any other single mining field of the globe. 



