BY F. D. POWER, F.G.S. 27 



different types of ore deposits. The most widely known, 

 perhaps, is that called the " Iron Blow," on account of the 

 hugh boulders of hematite (specimen 556) outcropping on the 

 surface. Mounts Lyell and Owen (named after Professor 

 Owen) are two peaks of the West Coast Range, divided by the 

 Linda Valley, but connected on their western slopes by a 

 saddle, which forms a watershed, the drainage on the east 

 flowing down the Linda into the King River, and that on the 

 west finding its way into the Queen River. That portion of 

 the Iron Blow worked by the Mount Lyell Gold Mining 

 Company is situated on the eastern side of the Mount Owen 

 end of the saddle. The country rock about here consists of 

 sandstones, green— (specimen 546) and red (specimen 551), 

 bleached at the surface (specimen 553) ; various schists — 

 ferruginous (specimen 550), talcose (specimen 548), hydro- 

 mica (specimen 547), etc.; and limestone (specimen 552), 

 which has a schistose structure. The general strike of these 

 rocks is approximately parallel with the West Coast Range, 

 aud also the sea coast in these parts. The older rocks are 

 overlaid with a quartz conglomerate (specimen 549), which 

 caps the highest points of Mounts Lyell and Owen. 



The Iron Bloiv Deposit. — Mr. G. Thureau believes this lode 

 to be due to thermal action, but after carefully going over the 

 ground three or four times I failed to find any facts which 

 would confirm this theory. 



Some people are pleased to consider this a so-called " true 

 fissure lode," but this fissure theory, which has been applied 

 to the majority of lodes, is fast dying out, for, assuming a 

 fissure to be formed for the sake of argument, any man 

 accustomed to mining is aware that conditions which would 

 enable the walls of that fissure to keep open until the inter- 

 mediate space was filled up with mineral matter by means of 

 water must be very rare indeed. If the country rock has 

 simply been loosened by some dynamical agency, or even if a 

 fault caused a fracture and displacement of the rock, any 

 cavities due to irregularities of the walls would be filled up 

 with rubbed off portions of the sides which have been loosened 

 by the movement, thus packing the space between the walls 

 like mullock in a worked-out lode. There is, then, no fissure, 

 and the whole affair must be relegated to an exaggerated 

 form of loosened country, the interstices of which sve filled 

 with metallic minerals brought in by solution, which cement 

 together the brecciated and powdered rock, sometimes even 

 replacing it. However, the Iron Blow shows no signs of this, 

 but, on the contrary, gives every indication of belonging to 

 that class of dejjosit known as segregation lodes. 



The two prevailing tints that the sandstones and schists 

 assume when not bleached are green and red. Some of the 

 bands of rock appear to have concentrated more iron than 



