28 NOTES ON THE MOUNT LYELL DISTRICT, TASMANIA. 



others, at the expense of their neighbours, and at times we 

 get very dark shades indeed ; in fact, in places it is com- 

 pletely turned into hematite, which retains the same laminated 

 structure that the original rock possessed. This transforma- 

 tion can be traced in its various stages until we come to what 

 we may consider the adult or perfect state, as exhibited in the 

 Iron Blow. This deposit has not been actually traced for any 

 great length, but a similar class of stone has been found here 

 and there on its course so far north as Mount Sedgwick, but 

 whether these outcrops belong to the same layer of altered 

 schist or to parallel ones will not interfere with any interpre- 

 tation of their segretative character. Although the Iron 

 Blow is composed for the most part of hematite, it is not on 

 account of its iron that it is worked, but because it is found 

 to be the matrix for gold. Besides hematite we also find a 

 fair amount of baryta (specimen 558), but, curiously enough., 

 very little quartz. The footwall is red sandstone, with 

 quartz, and the hanging wall iron pyrites, which we will 

 speak of later on. The general strike is nearly north and 

 south, though locally both strike and underlay vary consider- 

 ably, which is just what one would expect in a disturbed 

 country like this. The hematite may be divided into two 

 classes, according to its hardness, these occurring in alternate 

 bands, the softer portion looking as if it had been loosened 

 by friction. 



We now come to a very important point. There has 

 evidently been some great strain about here, as indicated by 

 cracks in the sandstone and conglomerate filled with quartz, 

 and in the limestone, occupied with calcite ; also by the fact 

 that the conglomerate found on the tops of the mountains 

 only occur in broken patches on the saddle. I am inclined to 

 think that as the peaks of Mounts Lyell and Owen were 

 formed the land piled up at those points was robbed from 

 what are now valleys, the dragged out appearance of the 

 country leaving one under that impression. The great weight 

 of these accumulations could not be without effect on the 

 weakened neighbourhood, and when settling down it would 

 have the same effect as if one were to catch hold of opposite 

 ends of a pamphlet and press them towards each other, if I 

 may be allowed to make use of a homely illustration. If this 

 took place after most of the Iron Blow hematite was deposited 

 it would account for some of it appearing to be rubbed up 

 along the lines of least resistance, which are coincident with 

 the planes of bedding and cleavage. It would also account 

 for another deposit adjoining the Iron Blow, though entirely 

 distinct from it. On the hanging wall of the hematite, as 

 before mentioned, is a large deposit of iron pyrites (specimen 

 555). If we examine the structure of this we find that when 

 undecomposed it is inclined to be schistose, and has a remark- 



