common use for large sheets of ice several acres in area, which are sometimes floated off from the rivers as the tide rises, with sedge and other salt-marsh plants frozen into their lower surfaces; also with mud adhering plentifully to their roots. In our speculations, therefore, on the carrying power of ice, we ought always to remember that, besides gravel and large fragments of rock, it transports with it the finest mud. Dr. Harding informed me that the surface of mudbanks along the estuaries near Wolfville, are often furrowed with long, straight, and parallel ruts, as if large waggons had passed over them. These conform in their general direction to the shore, and are produced by the projecting edges of irregular masses of packed ice, borne along by the tidal current. 148 COAL FORMATION CHAP. XXIV. CHAPTER XXIV. Coal Formation of Nova Scotia.-Productive Coal Measures.— Erect Fossil Trees in the Cliffs of the Bay of Fundy.—Section from Minudie to the South Joggins.—Ten buried Forests, one above the other.-Connection of upright Trees with Seams of Coal.-Stigmaria.—Sigillaria.-Evidence of Repeated Submergence of dry Land.-Theory to explain the Evenness of the Ancient Surface.-Pictou Coal-field.-Bed of Erect Calamites, compared to those of St. Etienne, in France.-List of Species of Nova Scotia Coal-plants.—Four-fifths of these Fossils identified with European Species.-Carboniferous Flora of the United States. ABOVE the granite, clay-slate, quartzite, and Silurian formations of Nova Scotia, there occur, in the northern part of the peninsula, as stated in the last chapter, strata referable to the carboniferous group, occupying very extensive tracts, and resting unconformably on the rocks of the older series. They may be divided into three formations; the middle one, comprising the productive coal-measures, agreeing precisely with those of Europe in their lithological characters and organic remains; an upper one, composed of sandstone and shale with fossil plants, but without coal; and a lower carboniferous group, chiefly made up of red sandstone and red marl, with subordinate beds of gypsum and marine limestone. In this lower series there are also occasionally some beds of shale with plants, and some coal-grits, and thin seams of impure coal. A variety of opinions have been entertained re specting the true age and position of the last-mentioned or gypsiferous formation, which has been generally presumed to be newer than the coal,-by some referred to the New Red sandstone, and even thought to overlie the coal-measures unconformably. Immediately after my return to England, I communicated to the Geological Society my opinion; 1st, that the gypsiferous formation, with its accompanying fossiliferous limestones, is a true member of the Carboniferous group; 2dly, that its position is below the productive coal measures.* I shall now give some account of these middle or productive coal measures, which contain valuable seams of bituminous coal, at various places, especially near Pictou. I was particularly desirous, before I left England, of examining the numerous fossil trees alluded to by Dr. Gesner as imbedded in an upright posture at many different levels in the cliffs of the South Joggins, near Minudie. The cliffs belong to the Cumberland coal-field, on the southern shores of a branch of the Bay of Fundy, called the Chignecto Channel, which divides part of New Brunswick from Nova Scotia. The first allusion to the trees which I have met with, is that published in 1829 by Mr. Richard Brown, in Halyburton's Nova Scotia, and he attributed their fossilisation to the inundation of the ground on which the forests stood. I felt convinced that, if I could verify the accounts of which I had read, of the superposition of so many different tiers of trees, each representing forests which grew in succession on the same area, one above the other; * See Proceedings of Geol. Soc., vol. iv., p. 184. 1843. 150 ERECT FOSSIL TREES. CHAP. XXIV and if I could prove at the same time their connexion with seams of coal, it would go farther than any facts yet recorded to confirm the theory that coal in general is derived from vegetables produced on the spots where the carbonaceous matter is now stored up in the earth. At Wolfville I hired a schooner, which soon carried us across the Basin of Mines to Parrsborough. We had a side wind, and the deck was inclined at about an angle of 45°, in spite of which we admired a splendid view of the coast, and the range of basaltic rocks which extend from Cape Blomidon to Cape Split. At Parrsborough I was joined by Dr. Gesner, who had come expressly from New Brunswick to meet me; and we went together to Minudie, a thriving village, where we were hospitably received by the chief proprietor and owner of the land, and of many of those fertile flats of red mud before described, which he has redeemed from the sea. From Minudie, a range of perpendicular cliffs extends in a south-westerly direction along the southern shore of what is commonly called the Chignecto Channel. The general dip of the beds is southerly, and the lowest strata near Minudie consist of beds of red sandstone, with some limestone and gypsum, a, b, fig. 18. The section is then very obscure for about three miles, or from b to c, the rocks consisting chiefly of red sandstone and red marl, after which, at c, blue grits are seen, inclined to the S.S.W. at an angle of 27°, affording an excellent grindstone, and attaining a thickness of forty-four feet. These beds. are succeeded to the south by a vast series of newer and conformable strata, all dipping the same way, |