best for the turner and the wood-engraver. It is made by the villagers into little boxes for holding ghee, honey, snuff, and tinder. At the medical stores in Sealkote it is turned into pill-boxes; and it appears to be adapted for plugs, trenails, and wedges. The wood is very heavy, and does not float; it is liable to split in the hot weather, and should be seasoned, and then stored under cover. "The Olive Zaitoon, which has also been tested for woodengraving at the Madras School of Arts, is another plant of the Mediterranean Flora which range from the coast of the Levant to the Himalaya. It varies a good deal in the shape of its leaves and in the amount of ferruginescence; hence the synonyms cuspidata and ferruginea: but it does not appear to differ specifically from the Olea Europea of the Mount of Olives, the emblem of peace and plenty. The finest specimens I have seen are in the Kaghan and Peshawur valleys, where the fruit resembles that of rocky sites in Palestine or Gibraltar. The wood is much used for combs and beads, and is found to answer for the teeth of wheels at the Madhopore workshops." 25. NETTLE FIBRE.--It is perhaps not generally known in Canada that the exquisitely beautiful fibre known as China grasscloth, and so much in favor for the best kinds of ladies' handkerchiefs, is obtained from an Indian nettle. No doubt the American Urtica gracilis, which grows abundantly about the Falls of Niagara and elsewhere in Canada, might be turned to good account, were our Agricultural Associations to direct attention that way. Dr. Cleghorn tells us that the Urtica heterophylla (the species cultivated by Mr. McIver at Ootakamund) is plentiful in Simla, having followed man to the summit of Jako, attracted by moisture to an elevation unusual for any member of the family. It is found within the stations of Dalhousie and Dharmsalla, and at many intermediate points. The quantity is surprising, wherever the soil has become enriched by the encamping of cattle. The growth at this season also is luxuriant in shady ravines near houses, where there is abundance of black mould; but the sting being virulent, the plants are habitually cut down as a nuisance, both by private persons and municipal committees. There are other plants of the nettle tribe, particularly Bohmeria salicifolia, "siharu," used for making ropes (to which attention has been directed by Dr. Jameson). This plant does not sting, and is abundant at low elevations. Large prizes were to be given for quantities of the nettle fibres to be delivered at Lahore in October 1863. The fibre brings from £16 to £18 sterling per ton in London. 26. DIATOMS OF THE SOUTH PACIFIC.-Dr. Greville has described, with exquisite figures, (Trans. Bot. Soc. Ed.,) numerous new species of diatoms obtained from dredgings in the South Pacific. There are two new genera, viz.: Stictodesmis, Grev., and Omphalopsis, Grev., and thirty-one new species. Halifax, N. S. Jan. 7, 1864. (To be Continued.) CAVE IN LIMESTONE NEAR MONTREAL. Under a similar heading to the above, this cave is noticed in the Canadian Naturalist and Geologist, Vol. III, page 192. To that article we would refer those interested, for the exact position of this cave. The party or parties, who then visited this curiosity-if I may so call it-found it filled with several feet of water, and were unable to give it any satisfactory examination. On the 11th of November last I visited the cave, and had no difficulty whatever in finding it. Of late years, the entrance has been considerably enlarged. Formerly, the opening was situated between the roots of a tree, which is yet standing in the vicinity; but some time since, the earth was slightly cut away, exposing the surface of the rock, and greatly enlarging the means of access to this cavern. From the outside, the limestone has a very rusty and weather-worn appearance, and is of a shaly texture. The whole surface is filled with the fossil shells and corals peculiar to the Trenton limestone. The mouth of the caves is about four feet high, by six feet in width. On entering, I was agreeably surprised to find that the water had entirely subsided into a narrow well, or fissure in the floor, some twenty feet distant from the mouth of the cave. Standing by this well, the room was about thirteen feet high by eight feet in width. The walls jutted out irregularly on either side, but gave the average width of eight feet. The ceiling was also of limestone rock, and coated over with stalactitic carbonate of lime, from which hung a few small stalactites. In the sides of the chamber were numerous deep fissures, hardly large enough to admit an arm, and lined with the same mineral. In these fissures could be seen very perfectly the formation of satalactites and stalagmites,-the former meeting the latter half way. Some of the stalactites were of a beautiful needle-like shape, and about four or five inches long. These we could not procure, as they were beyond our reach; but they may be plainly seen by holding a candle in the crevice. Before passing farther into the cave, let us for a moment examine the well. It is affirmed by the people in the neighborhood that no bottom has yet been found to it. But on questioning them, we found that their bottomless measure was two pairs of reins tied together. It is however a difficult depth to measure, as it runs down very irregularly, and at angles. The water is clear, and very cold, and has a strange greasy touch. It is surprising to see its transparency, when it has this thick and oily touch; it yet remains to determine whether this well is fed by springs, or by the drippings from the roof of the cavern. Leaving the well, we push on, and after ascending a few feet, come to two passages, one leading to the right, the other to the left. The entrance to the one on the right is about two feet square, and leads into a small room or passage running into the rock. This passage is about thirty feet long, and two or three broad, ending in a narrow fissure which seems to run deep into the limestone. This fissure is too small for one to enter with any comfort, though I believe it widens some few feet farther in. Turning with difficulty, we retraced our steps, and came before the passage running to the left. This at the entrance was two feet high and six feet wide; but on entering, we found ourselves in a small room, about eight feet high, and six wide. At its extremity another fissure ran down into the rock, which looked as if it had at one time been a pretty large passage. Indeed, so shaly and loose are these rocks, that by the action of water and the frosts, this cave may be, ere long; entirely blocked up. The habitans state that it was at one time much larger than it is now. In the first, or entrance-chamber, were found sticking to the roof, and sparkling with moisture, six beautiful species of moths: two of these, are now in the Society's collection. These moths were snugly ensconced in the cracks of the rock, sleeping quietly, until the genial breath of spring and the songs of returning birds should rouse them again to their out-door employments. Besides moths, bats also had taken up their quarters in this cave, and flew around, sadly disconcerted. by our intrusion. In the paper alluded to in the beginning of this article, it was stated that if the water could be pumped out of this cave, bones might be found at the bottom. I may just mention, before concluding this brief description, that the cave is now entirely free from water, and that no bones have been found as yet; but a search into and amongst the loose soil at the bottom, may be, and I think would be, well worth attempting. CONTRIBUTIONS TO LITHOLOGY.* BY T. STERRY HUNT, M.A. F.R.S.; of the Geological Survey of Canada. INTRODUCTION. In a recent paper on The Chemical and Mineralogical Relations of Metamorphic Rocks (Silliman's Journal [2], xxxvi, 214),† an attempt was made to define the principles which have presided over the formation of sedimentary rocks, and to explain the nature and conditions of their alteration or metamorphism. That paper may be considered as to a certain extent introductory to the present one, which will contain, in the first part, some theoretical considerations which it is conceived should serve as a basis to lithological studies. In the second part will be given a few definitions which may serve to render more intelligible the classification and nomenclature of crystalline rocks; while a third part will contain the results of the chemical and mineralogical examination of some of the eruptive rocks of Canada; and a fourth, some examples of local metamorphism. The most of the results appear in the recent published Geology of Canada. I. THEORETICAL NOTIONS. I have already, in other places, expressed the opinion that the various eruptive rocks have had no other origin than the softening and displacement of sedimentary deposits; and have thus their source within the lower portions of the earth's stratified covering, and not beneath it. The theory which conceives them to have been derived from a portion of the interior of the earth still retaining its supposed primitive condition of igneous fluidity, is in my From Silliman's Journal Vol. xxxvii, page 248. ↑ Canadian Naturalist, Vol. viii, page 195. opinion untenable. It is not here the place to discuss the more or less ingenious speculations of Phillips, Durocher, and Bunsen as to the constitution of this supposed fluid centre, nor the more elaborate hypothesis of Sartorius von Waltershausen as to the composition and arrangement of the matters in this imaginary reservoir of plutonic rocks. The immense variety presented in the composition of eruptive masses presents a strong argument against the notion that they are derived, as these writers have supposed, from two or more zones of molten matter, differing in composition and density, and lying everywhere beneath the solid crust of the earth; which, in opposition to the views of many modern mathematicians and physicists, the school of geologists just referred to regard as a shell of very limited thickness. The view which I adopt is one the merit of which belongs, I believe, to Christian Keferstein, who, in his Naturgeschichte des Erdkörpers, published in 1834, maintained that all the unstratified rocks, from granite to lava, are products of the transformation. of sedimentary strata, in part very recent; and that there is not well-defined line to be drawn between neptunian and volcanic rocks, since they pass into each other (vol. i, p. 109.) This view was subsequently, and it would seem, independently brought forward in 1836 by Sir John Herschel, who sought to explain the origin of metamorphism and of volcanic phenomena by the action of the internal heat of the earth upon deeply buried sediments impregnated with water. (Proc. Geol. Soc. of London, vol. ii, pp. 548, 596.) See also my papers in the Canadian Journal, 1858, p. 206; Quar. Jour. Geol. Soc. 1859, p. 488; Can. Naturalist, Dec. 1859; and Silliman's Journal [2], vol. xxx, p. 135. The presence of water in igneous rocks, and the part which it may play in giving liquidity to all volcanic and plutonic rocks, was insisted upon by Poulett Scrope, so long ago as 1824, in his Considerations on Volcanoes. (See also Quar. Jour. Geol. Soc. London, xii, 341.) This view has since been ably supported by Scheerer in his discussion with Durocher. (Bul. Soc. Geol. France [2], iv, 468, 1018; vi, 644; vii, 276; viii, 500.) See also Elie de Beaumont, ibid., iv, 1312. The admirable investigations of Sorby on the microscopic structure of crystals (Quar. Jour. Geol. Soc., xiv, 453) have since demonstrated that water has intervened in the crystallization of almost all plutonic rocks. He has shown that the quartz VOL. I. B No. 1. |