AURIFEROUS REEFS. 19 



The fact that similar reefs, apparently corresponding in strike and 

 continuous with some of the outcrops in south-east Wain£d, occur 

 in Malabar at the foot of the plateau,— i.e., over two thousand feet 

 lower down, — was considered by Dr. King as a strong argument in 

 favour of a great extension in depth, and although such a conclusion 

 would seen at first sight quite justifiable, yet owing to the great 

 difficulty of proving a connection to exist between any two isolated 

 outcrops, too great weight cannot be attached to this argument. 

 So far, however, as it has been possible to examine the more import- 

 ant reefs in south-east Waina'd, there is no reason to suppose that 

 in most cases they are not continuous to a considerable distance both 

 vertically and horizontally. Thus the reef at the Alpha mine, near 

 Devala, has been proved, by numerous drives, to a depth of about 

 400 feet below the surface outcrops and shows no signs of pinching 

 out. The reef at the Phoenix mine, however, near Pandalur, which 

 has also been opened up to a considerable extent, was eventually lost 

 in most of the drives and Dr. Hatch 1 found it to consist of a 

 series of lenticular masses. Again, in south Wain£d, the reef on 

 the " Cootacovil " property, which is said to have yielded very 

 good results, consisted only of a small isolated body of ore, which was 

 completely removed, and all attempts to find any continuation of it 

 were futile : this is said to have occurred also in several other 

 instances. Although, therefore, some of the reefs may with a fair 

 degree of certainty be described as " true " or " fissure " veins, 2 yet 

 many of the ore-bodies are merely small irregular patches, which 

 even though rich, are not of sufficient extent to be of any material 

 value. 



The country* rock is in most cases biotite gneiss, which is decom- 

 posed, to a considerable depth below the surface, 

 Country-rock. . ' . A , 



into a soft arenaceous clay. As already stated 



1 See below, p. 29. 



1 The sense in which these terms are used is that defined by Phillips and 

 Louis : " A treatise on Ore Deposits," 2nd Edn. (1896). 



C2 ( 19 ) 



