CHAP. 1.] PREVIOUS OBSERVERS. '5 
and his ideas on the geology of the country were guided by its teach- 
ing. He calls the series of rocks, with which the diamond beds are 
associated, the “ Clay Slate Formation,” and says of 1t—“ I do not mean 
the Wernerian Thonschieffer, the fourth in order, of his enumeration of 
primary rocks, but merely a collection of rocks which I conceive to have 
been placed in their present situation at the same period of time.” 
He calls the diamond gangue a sandstone-breecia, whereas it is more 
of a pebble bed ; but his account of the constituents of the rock is very 
correct. He also falls into the same confusion, in which most of the 
subsequent writers have involved themselves, regarding the extent and 
position of the band of quartzites containing the diamond beds. There 
are in the KARNUL formation two well separated bands of quartzites, 
and the out-crops of these on opposite sides of valleys, for instance, 
have been taken for one and the same band. Indeed, there are numerous 
bands of quartzites in the lower or KADAPAH formation; and nearly all 
the observers have apparently taken it for granted that all these, as well 
as those of the KARNUL group, are but one great series. The con- 
sequence is that Voysey, as well as the other writers, refers vaguely to 
the extent of the diamond-bearing beds. He makes three deductions 
at the end of his paper which are partly eorrect :— 
` © Jst.— That the matrix of the diamonds produced in Southern India 
is the Sandstone Breccia of the Clay Slate Formation." The diamonds, 
at present worked, are confined to only one group of quartzite in the 
KARNUL formation; but old mines appear to have been excavated indis- 
criminately in several bands of ! quartzite both in the KARNÚLS and 
KADAPAHS in the Kistnah District. Whether these always produced 
diamonds is not an ascertained fact; and some of them are in gravel 
deposits which very probably resulted from the denudation of the proper 
diamond-bearmg beds in the KARNULS. 
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Cx 
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