the
Central Provinces which are referred to are not of the same age as the
sandstones of Southern India which accompany the diamond-bearing
strata; they are in fact very much younger, and Messrs. Hislop and
Hunter were no doubt correct in asserting that the diamonds of the
lateritic gravel had not been derived from them. But the mention of the
quartzose meta-morphic rock confirms what is independently probable
—namely, that the great basin of lower Vindhyan or Karnul rocks which
occupies the upper portion of the Mahanadi valley stretches into the
neighbourhood of Weiragurh, and it may, therefore, be suggested with a
considerable degree of probability that the ultimate derivation of
these diamonds is from a stratum occupying a horizon identical with
that which constitutes the matrix of the Sambalpur diamonds, and as
that in a general way has already been correlated with the diamond
horizon in the Karnul rocks, the theories of both sets of observers
contained hypotheses partly correct and partly erroneous, the correct
portions respectively supplementing one another. Malcolmson and Newbold
were right in supposing that the diamonds of Weiragurh indicated the
existence of rocks of the same age as those of Southern India (the
Karnul formation), but were wrong in supposing that the fossiliferous
sandstones which they referred to included the source of the gems. On
the other hand Messrs. Hislop and Hunter, while pointing out the latter
mistake, did not realize the existence of another formation close by
from which the gems probably did originally come. They seemed to regard
the diamonds, both here and elsewhere throughout India, as being a
product of superficial deposits, without reference to the nature of the
beds upon which they rested.
