Thus perhaps the pudding-stone of the south of England will be considered in the same light as having been formed of the débris and détritus of the flinty bodies.
In the island of Arran, there is also a pudding-stone, even in some of the summits of the island, exactly upon the border of the schistus district, as will be described in the natural history of that island. This pudding-stone is composed of gravel formed of the hardest parts of the schistus and granite or porphyry mountains. That compound parasitical stone has been also again cemented by heat and fusion; I have a specimen in which there is a clear demonstration of that fact. One of the water-worn stones which had been rounded by attrition, has in this pudding-stone been broken and shifted, the one half slipping over the other, three quarters of an inch, besides other smaller slips in the same stone. But the two pieces are again cemented; or they had been shifted when the stone was in that soft state, by which the two pieces are made perfectly to cohere. Those shifts and veins, in this species of stone, are extremely instructive, illustrating the mineral operations of the globe.
In like manner to the north of the Grampians, along the south side of Loch Ness, there are mountains formed of the debris of schistus and granite mountains, first manufactured into sand and gravel, and then consolidated into a pudding-stone, which is always formed upon the same principle. The same is also found upon the south side of those mountains in the shire of Angus.
I may also give for example the African Brechia, which is a pudding-stone of the same nature. This stone is composed of granites or porphyries, serpentines and schisti, extremely indurated and perfectly consolidated. It is also demonstrable from the appearance in this stone that it has been in a softened state, from the shape and application of its constituent parts; and in a specimen of it which I have in my cabinet, there is also a demonstration of calcareous spar flowing among the gravel of the consolidated rock.
This fact therefore of pudding-stone mountains, is a general fact, so far as it is founded upon observations that are made in Africa, Germany, and Britain. We may now reason upon this general fact, in order to see how far it countenances the idea of primitive mountains, on the one hand, or on the other supports the present theory, which admits of nothing primitive in the visible or examinable parts of the earth.
To a person who examines accurately the composition of our mountains, which occupy the south of Scotland, no argument needs be used to persuade him that the bodies in question are not primitive; the thing is evident from inspection, as much as would be the ruins of an ancient city, although there were no record of its history. The visible materials, which compose for the most part the strata of our south alpine schisti, are so distinctly the debris and detritus of a former earth, and so similar in their nature with those which for the most part compose the strata on all hands acknowledged as secondary, that there can remain no question upon that head. The consolidation, again, of those strata, and the erection of them from their original position, and from the place in which they had been formed, is another question.
But the acknowledging strata, which had been formed in the sea of loose materials, to be consolidated and raised into the place of land, is plainly giving up the idea of primitive mountains. The only question, therefore, which remains to be solved, must respect the order of things, in comparing the alpine schisti with the secondary strata; and this indeed forms a curious subject of investigation.
It is plain that the schisti had been indurated, elevated, broken, and worn by attrition in water, before the secondary strata, which form the most fertile parts of our earth, had existed. It is also certain that the tops of our schistus mountains had been in the bottom of the sea at the time when our secondary strata had begun to be formed; for the pudding-stone on the top of our Lammermuir mountains, as well as the secondary strata upon the vertical schisti of the Alps and German mountains, affords the most irrefragable evidence of that fact.
It is further to be affirmed, that this whole mass of water-formed materials, as well as the basis on which it rested, had been subjected to the mineral operations of the globe, operations by which the loose and incoherent materials are consolidated, and that which was the bottom of the sea made to occupy the station of land, and serve the purpose for which it is destined in the world. This also will appear evident, when it is considered that it has been from the appearances in this very land, independent of those of the alpine schisti, that the present theory has been established.
By thus admitting a primary and secondary in the formation of our land, the present theory will be confirmed in all its parts. For, nothing but those vicissitudes, in which the old is worn and destroyed, and new land formed to supply its place, can explain that order which is to be perceived in all the works of nature; or give us any satisfactory idea with regard to that apparent disorder and confusion, which would disgrace an agent possessed of wisdom and working with design.