186. This description is no doubt accurate, though it involves in it something of theory, viz. that the fracture was made by the weight of the stone. This may indeed be true: the operation probably belongs altogether to the surface, and is one with which the powers of the mineral regions are not directly concerned. The phenomenon, however, appears to me, on every supposition, very difficult to explain. In the specimen which I brought from Oban, the smallest pieces of stone are cut in two, as well as the largest. The consolidation and hardness of the mass are very great, and the connection of the different fragments so perfect, that it is no wonder the whole should break as one stone. But still, that the fracture should be so exactly in one plane, and without any shattering, is not a little enigmatical; if it is indeed a fracture, it must be the consequence of an immense impulse, very suddenly communicated.
Note xii. § 43.
Elevation and inflection of the strata.
187. The evidence of the different formation of the primary and secondary strata, and of the changes which the former have undergone, is best seen at the points where those strata come into contact with one another. Dr Hutton was not the first who observed these junctions, though the first who rightly interpreted the appearances which they exhibit. He has mentioned observations of this sort by De Luc on the confines of the Hartz; by the author of the Tableau de la Suisse, at the pass of Yetz; by Voight, in Thuringia; and Schreiber, at the mountain of Gardette.[94]
[94] Theory of the Earth, vol. i. p. 410 to 453.
The leading facts to be remarked, are,
I. The vertical or very upright position of the primary or lower strata.
II. The superstratification of the secondary, in a position nearly horizontal, so as to be at right angles to those on which they rest.
III. The interposition of a breccia between them or, as happens in many cases, the transition of the lowest of the secondary beds into a breccia, containing fragments sometimes worn, sometimes angular, of the primary rock.
This last is a phenomenon extremely general, and all our subsequent information confirms Dr Hutton's anticipations concerning it. "It will be very remarkable," he says, "if similar appearances, (such as those of the breccia described by Voight,) are always found upon the junction of the Alpine with the level countries."[95] Saussure, in a part of his work, not published when Dr Hutton wrote this passage, has attested the generality of the fact with respect to the whole Alps, from the Tyrol to the Mediterranean: "Un sait que l'on observe sans aucune exception, ce sont les amas de débris, sous la forme de blocs, de breches, de poudingues, de grès, de sable, ou amoncelés, et formant des montagnes, ou des collines, dispersés sur le bord exterieur, ou même dans les plaines qui bordent la chaine des Alpes."[96]