page 211 note * The italics are the writer's, not Dr. Macculloch's.

page 221 note * Analysis deferred (though material prepared) wherever P. attached.

page 230 note * I have been much surprised to read, in a foot-note to an excellent paper by Professor Bonney on the Petrology of the neighbourhood of Loch Maree, the following—“My friend Mr. L. Ewhank, tells me that near Dundonnel (Little Loch Broom) he traced a gradual passage from the one to the other,” (i.e. from the conglomerates into the quartzite) * * the break therefore is probably rather local than general.” My surprise was occasioned not merely by the conclusions of Murchison,–and, as regards this point, it may be said, of every one else,—being set aside in a foot note, and upon the evidence of of certainly a comparatively unknown man, but from the Dundonnel district being quoted as proving conformity. Though I have not examined the district named to nearly the same extent as I have done those to the north. I have no hesitation in saying that it exhibits a very much more highly marked uncomformity of the formations, than is seen in the northerly districts. In referring to this point in the previous number of the Magazine, when speaking of Quinaig, I stated that the general dip of the conglomerate might be put at 5° and of the quartzite at 7°. Now, as we proceed southward, the dip of the conglomerate increases, as does that of the quartzite, but that of the latter does so in a very much greater degree. In other words, the amount of diagonal denudation of the conglomerate is much greater in the southerly than in the northern districts. To anyone who doubts this, I would recommend a study of the manner in which the quartzite sweeps up over the denuded, and at some points, actually fretted beds of the great hill Teallich : or a consideration of the sections to the south of this, given by Geikie in the XVII vol. of the Quarterly Journal of the Geological Society.

Professor Geikie and I have, in companionship,, gone over a not inconsiderable portion of this northern district ; I have seen his pencil working, and I can vouch for his accuracy. I can also vouch for his caution for he has asked me to climb to doubtful points, and trace out flexures ;—demonstrating to him while he drew beneath. As to the “break being rather local than general,” I have only to say, that, while I have seen one or two points where there was an apparent conformity when examined along the strike, I have seen no spot in the whole distance between Kyle Sku and Looh Torridon where there was not a palpable unconformity, when examined at any angle thereto.

page 237 note * A piece of the rock wss got which had a very perfect and fine twin, imbedded in it, showing beautifully the angle of t on t. The measurement of this would have settled the question as to whether these crystals were albite or oligoclase ; it was therefore sent to London to be sliced, but it was broken through the carelessness of a workman.

page 246 note * It is not altogether easy to make out whether Sir R. Murchison ever was among those who so agreed ; nor indeed, is it easy to arrive at any conclusion as to his views. Writing in 1858 we find that on one page he says regarding them—“the ascending order of the quartz-rocks and limestones is everywhere the same as in Assynt, i.e. a strong band of limestone interposed between masses of regularly stratified quartz-rock.” Two pages further on he writes—“The reversal by which the Durness limestone is thus placed in a trough of quartz-rock and underlying limestone, has been manifestly occasioned by a great upheaval of the old gneiss when acted upon by eruptive forces, of which clear signs are manifested in the adjacent Bay of Sangoe. There huge bosses of black hornblendie and hypersthenic rock stand out with serpentinous coatings,—the courses of the limestone in their vicinity being singularly altered, mottled and dolomitie —“ there is no doubt that the limestone and underlying quartz-rock of Durness occupy a trough.” In 1859 again he writes—“This tract has been subjected to so many dislocations, that in one line of traverse only, or that in which my former section passed, can it be viewed as unbroken,—no other section represents a trough. On the contrary, the limestone is thrown abruptly into contact with the old gneiss of Kennabin on the northeast; and constitutes a narrow wedge-shaped mass between that fault and an equally large one which truncates it against the old gneiss on the west side.” But other observers, e.g. Harkness and Nicol, have shown that so far from being “unbroken” in the line of Murehison's first section, the lime is cut up into quite a multitude of fragments along that line. The theory of a great upheaval of the old gneiss at Keannabin by huge bosses of eruptive rocks in Sangoe bay, which simultaneously altered the limestone, I shall advert to after.

page 248 note * An average sample of this limestone was lately forwarded by me to Messrs. King and Hunter, the city analysts of Edinburgh,—without any information as to its source, or indication that it was in any way of special interest. My instructions were to determine merely the lime and magnesian carbonates,—but to do this with scrupulous care.

These gentlemen write :—“ The total CaO present is 50·82 per cent, which calculated to Carbonate yields 90·75 per cent. of Ca CO₃. The total MgO present is 1·60 per cent, calculated to Mg CO₃ would yield 336 per cent. Of course some of the lime and magnesia may not exist as carbonate.”

page 250 note * An examination by the microscope of the silicious residue of this lime, when treated with acids, showed nothing clearly except silicious rods, much resembling fragments of the rootlets of the rope sponge. They were very much more minute

page 250 note † Sir R. Murchison writes,—“ some of the exposed points or knobs are surrounded or partially wrapped over by a tufa-like silicious sinter, sometimes resembling a breccia, which conveys the idea of a boiling over of such matters when the rock underwent the metamorphism to which it has evidently been subjected. Even in this bard matrix my companion detected traces of fossils. The most marked of the external characters of the limestone is its coarse rugosity—the result probably of weathering 6upon its peculiar composition, and which gives the scarps of the rock the appearance of an elaborately wrought rustic basement of a Florentine palace.” While I would not ask any chemical reader to believe in a boiling silica remaining inert as regards the lime over which it boiled, still the above is a geologic admission of extreme and evident metamorphism, and of a “composition” “peculiar” as regards the “limestones” of the district.

page 253 note * Not upon merely petrological or chemical grounds alone, but upon geognostical also would it be of surpassing interest if we could obtain portions of an eruptive rock which had risen from beneath the lowest rock of the knowa crust of the earth.