John MacCulloch

“ Viewing the whole of this compound mass of schist and limestone as a single rock, and the granite as another, it is easily seen on the most superficial glance, from the strong contrast between the dark grey of the former and the red of the latter, that the dark rock is intersected and disturbed by innumerable veins of granite. These traverse it in every possible direction, and are of various sizes, the smallest not exceeding that of a thread, and reticulating the dark rock in a most intricate and amusing manner. ”

“ Although the hills themselves which encircle the romantic valley and water of Coruisk are utterly inaccessible on this side, yet it is easy every where to examine their bases, while the continuity of the beds or sheets of rock, from the foot to the very summit of the ridge, and its remarkable external characters, leave no doubt respecting the identity of their composition throughout. This is the rock on which the elements seem to make no impression, and on which no soil accumulates, causes which equally determine the permanent and rugged nature of their spiry outline. ”

“ I would entreat the pardon of the Society for occupying so much of its time on the fracture of a schorl crystal, were I not persuaded that much light must at some period inevitably be thrown on the greater geological phenomena, by considering the chemical and mechanical relations existing among the smaller portions which constitute them, and that the language of Nature is often as intelligibly spoken in the minute space of an inch, as in the immensity of a mountain. ”

“ It would be a fruitless attempt to introduce the marble of Glen Tilt, or even those whiter varieties which Scotland produces, in competition with the exquisitely beautiful and easily wrought stone of Carrara, as long as these quarries remain accessible to us. For that higher class of sculpture on which the powers of genius are exerted, the proportion between the price of the wrought and unwrought article, (to use commercial phraseology) is so unequal, that no difference in the value of the raw material can compensate for even the most trivial defects in its quality. ”

“ If we examine a lake inclosed by hills of a considerable declivity, which, being formed of solid rock, are at the same time covered with alluvial matter to a greater or less depth, we find that it is skirted by a gravelly shore, forming an inclined plane and constituting a zone at the level of the water; of greater or less breadth according to the declivity of the hill, the quantity of alluvial matter present, and the nature of other circumstances which occasionally modify the action of these causes. ”

“ I have shown that quartz rock is here in contact with granite, and it is not therefore surprising that it should, like the mica slate with which it forms but one great deposit, undergo analogous changes when it approximates to this rock. The transition is in fact more easy and the boundary less definable, since many varieties of quartz rock, formed of felspar and quartz in varying proportions with an occasional mixture of mica, only require to assume that crystallized appearance which the vicinity of granite is so apt to produce on the neighbouring rocks, to become indistinguishable from it. ”

“ It ought therefore to be designated in a geological system by one general name, since, as the designations of rocks are intended for the purposes of geology, rather than of mineralogy, it is preferable that one common term should be applied to the rock in question, than that the several varieties should each receive a separate one, a circumstance tending as much to confuse geological reasonings, as to render them tedious and intricate. ”

“ We are yet, it is to be feared, in want of a theory capable of solving all the cases which the increased activity of geological research is daily bringing to light. It is among difficult and unexplained phenomena that we are to seek for the stimulus which will lead us to pursue those researches on the multiplication of which alone we can hope to found a true system; and it is to a salutary distrust of the all-sufficiency of any hypothesis, that we must look for protection from its paralyzing effects. ”

“ We have long been indebted to foreign countries for substances which our own island produces in abundance, and in no instance have the powers of established habits and prejudices been carried further than in the preference given to many of their insignificant marbles and porphyries, while our own, either similar or superior, have been neglected. To encourage commerce and the arts is not unworthy of a Society, which, like ours, has in view among other objects, the investigation of an important branch of the natural history of our own country. ”

“ If we now suppose the hardness of a mass of granite, or its resistance to the disintegrating power of air and water, to vary in any given ratio at certain distances from the centre, it is evident that the effect of chemical action on the surface, will be to change the figure of that mass, and that the ultimate effect will be to disclose the sphere inscribed within that cube. ”

“ Although there are five landing places about the island, there is no harbour where ships can lie, and but one beach where small boats can be wintered. Such is the nature of the cliffs, that except at the Creux, where a tunnel is cut through the rock, there is hardly any entrance to the land, but by climbing. It is a very strong natural fortification, and might at a small expence be rendered impregnable.
The rocks which compose the shores, being of various and generally line forms, afford a variety of singularly grand and picturesque scenery. ”

“ No apology can be offered for want of industry; but the extent of this island, the difficulty of traversing it, and the intricate disposition of its rocks, offer some excuse for deficiencies, where want of time was further superadded to all other obstacles. For errors there is no excuse, but in correcting them it will not be useless to point out the causes from which they arose, since other observers may take warning from them, and learn to mistrust all observations which are not founded on rigid investigation, free from conjecture, and free from system. ”

“ I have already said that in ascending Cruachan the schist soon disappears: at the same time the accumulation of soil and the covering of plants are so great, that it is scarcely possible to meet with the natural rock for at least half the ascent. Many masses which appear to be in their places, turn out on examination to be only large rolled stones, and these invariably consist of granite and porphyry. It is not till we have attained about two thirds of the height of the mountain, that the natural rock makes its appearance in an unquestionable manner. ”

“ Want of roads, want of horses, want of population, want of every thing, render this country among the most impracticable of Scotland.
The nature of this rock is exceedingly various. It is often a compact stone of a yellowish colour, and uniform texture, resembling granulated quartz, simple in its composition, and breaking with an imperfect conchoidal fracture. Occasionally it assumes a coarser and looser texture, and in these cases the weathered surface becomes white, and acquires a harsh and sandy feel and aspect. ”

“ If by any causes of a nature similar to those which we see in daily action on the surface of the earth, it must have been by the flowing of rivers upon them. Thus the flow of the Ness and the Spey towards the sea, might have lowered the land in these directions to their present level, and thus the exit of Loch Shiel might have destroyed the barrier to the west; while the repeated failures of the supposed barrier at the mouth of the Lochy had in the mean time produced the complete drainage of Glen Roy and Glen Gloy, and with the exception of Loch Laggan, that of the Spean. ”

“ It will be seen that there are yet points unexplained, particularly respecting the trap rocks, a circumstance which will not surprise geologists who know that to patience, toil, and good seasons, must often be superadded good fortune; the casual discovery of perhaps the only point over a wide tract which is capable of yielding the explanation of which we are in pursuit.
As the mica slate and its associate the quartz rock are the most ancient of those which I have ascertained in Sky, I shall commence from them as the foundation of the whole structure. ”

“ I have frequently noticed the transition which takes place between quartz rock and mica slate, a transition so gradual and so perfect that it is often impossible to assign the limits of the two. The quartz is often hyaline, while the mica is disseminated through it in scales of which the tendency, notwithstanding the crystalline state of the quartz, is parallel either to the laminæ or to the beds of the stone. These specimens when polished exhibit the characters of the most perfect avanturine, but their colours are only white or greyish. ”

“ For, the hornstone, the claystone, the trap and the felspar, which constitute the bases of these several rocks, although often containing crystals of felspar, are yet perhaps as frequently destitute of that accidental substance. I am not an advocate for increasing words, and encumbering our language with unnecessary terms, but that confusion which arises from applying one term to many substances, is at least as faulty and a greater cause of error than the accumulation of an unweildy stock of synonymous ones. ”

“ In these parts, thus subjected to the action of water, the limestone is dissolved and deposits here and there a white crust of carbonat of lime resembling the usual deposits of calcareous waters, so as to whiten in many places the surface of the rock. One cascade of considerable height has thus left the marks of its intricate course in the dark and broken rocks so perfectly, that even in dry weather it appears to be always flowing, and only a narrow inspection discovers it to be an imitation; a painted cascade formed by the hand of Nature. ”

“ The interior of the country is too much encumbered with peat and with vegetation to permit of any decision on a subject so obscure as is the point of change between the gneiss series and the rocks which follow it, and I must therefore limit myself to the appearances which occur on the sea shore, where every change can be traced in the most minute manner. Here there will be found a transition, unexpected and improbable as it may at first seem, between the two series, that of the gneiss, and that of the graywacké and sandstone which follows it ”

“ I should therefore suggest the superior propriety of the term quartzy or quartz rock, a term involving no hypothesis, and which, at the same time that it is sufficiently general to include all the varieties which consist of mere quartz, does not exclude those which contain a mixture of other ingredients, more than the terms sandstone or limestone exclude the various bodies which so often are mixed with, or constitute an integrand part of them. ”