Again,
would not the intrusion of an igneous rock through carbonaceous shales
have altered these shales in the vicinity of the igneous rock? There
is, however, no difference that can be detected between the shales at
the junction of the pipe and at a distance of one thousand feet.
Moreover, would not the fragments of shale enclosed in the blue ground
have changed, and have lost the carbon which they contain, if diamonds
were formed from them ? One sees no difference between the shale which
forms the country rock, and the fragments embedded in the blue ground.
If such a theory as is attributed to Professor Lewis by Mr. Kunz had a
shadow of foundation, it is dispelled by the occurrence of diamonds in
the Jagersfontein mine in the Orange Free State, some eighty miles from
Kimberley. The rocks surrounding this mine are gray shale from the
surface to the depth of twenty feet, and then basalt as far as
developed. It is apparent that no carboniferous shales ever existed
here, or
