6. The width of these veins does not always diminish as they recede from the main body of granite. Sometimes after a very slender beginning, they swell out, or divide into ramifications.
7. I did not find the veins extend very far, nor rise perpendicularly, on the contrary, I always observed those at the surface to be conformable with the planes of inclination of the ground.
8. At the point of contact of these two rocks I never found the one disseminated in small quantities through the other, the granite never mixes with the grauwacke, but both retain their distinct characters.[1]
9. In breaking a part of these veins with the hammer it generally happens that the grauwacke separates from the granite, which proves that there was no penetration, but only juxta-position, as if the one had been moulded in the crevices of the other.
Several of these facts appear to me not very easily reconcilable with the following assertion in the work of Mr. Playfair: I quote it in his own words, “ It remains certain therefore, that the whole mass of granite and the veins proceeding from it are coeval, and both of later formation than the strata”.[2]
To the latter part of the above quotation, I cannot assent; I conceive, that at the time the grauwacke was deposited upon the granite, the water in which its particles were suspended, meeting with portions of the granite, a little more elevated than the general plane of the surface, left them exposed, and filled up the spaces between
- ↑ At least, if anything of the kind has been observed, it has never been at such a distance as we might expect it to be, if produced by so considerable a force as that which the Huttonians suppose, but only at the edges; and in this case, it may have happened that the granite was softened by the grauwacke acting upon it as a solvent, so far as to permit pieces of that rock to amalgamate with it.
- ↑ Illustrations of the Huttonian Theory, § 82.
