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in the same order of superposition as we have described in the already noticed localities. Thus, limestone presents itself first as compact and non-fossiliferous, and then gradually becomes a fossiliferous, having for its base either the sedimentary rocks greywacke, clay slates, or siliceous breccia, or quartzose porphyry, greenstone, and basalt. The conglomerates and pudding-stones which are overlaying this limestone, are in a state of partial disintegration, particularly about Yass Plains.
In consequence of this disintegration, the limestone is left exposed. In Wellington Valley, Molong, and Boree, its examination is very interesting, owing to the osseous breccia found in its caverns. On the north of Mount Canoblas and Yass Plains it is likewise so, on account of some fossils more or less perfect: which may be referred to
Favosites Gothlandica, Crinoidal columns. Orthoceras, and Impressions of Trilobites, not exceeding half an inch.
In Van Diemen's Land, the locahties at which the rocks of the second epoch occur are : —
1st. Asbestos Hills on the south. — The lowermost of the series here appears to be a slaty, micaceous, and argillaceous rock, highly inclined, resting upon siliceous amygdaloid and breccia, and at times abutting on a greenstone rock. Next to it is seen a compact limestone, gradually becoming fossiliferous: over this is a conglomerate, in nearly horizontal beds.
2d. Rouse-top Tier (Hampshire Hills). — Feldspathic rock, with a slaty cleavage, at times conchoidal in fracture, is here the lowest member, resting either upon granite or feldspathic porphyry; and subjacent to a granular limestone, which is without fossils. ( Dr. Milligan.)
3d. From Emu Bay to Cape Grimm, extends a continuous tract of siliceous and argillaceous slates, reposing upon several parallel axes in the direction of north and south. The transverse section shows that the strata are contorted and wavy, with a varying inclination. The axes are composed either of granular quartz rock, basalt, greenstone, or a jasperoid rock; the slates are usually gritstones, and fine-grained, siliceous, and argillaceous slates of red, greenish, grey, black, and blue colour. This tract of slates is elevated but few feet above the highwater mark, and is surmounted here and there by horizontal beds of conglomerate.
4th. Belvoir Valley, Circular Pond Marshes, and the limestone caves of the River Mersey (Mr. Reid's farm), present similar geological features so far as regards the group of the second epoch. The three localities have for the lowest rock a flaggy gritstone, or granular quartz rock and clay slate, in an inclined position, resting upon quartz rock, feldspathic porphyry, greenstone, and basalt. A compact limestone, pudding-stones, and conglomerates are associated with them: the last is in horizontal beds. No organic remains have as yet been discovered here.
The limestone of the above three localities is much traversed by greenstones and basalts, and exhibits, in the structure of the caverns which it forms, and in the funnel shape which the surface in many places assumes, marks of partial subsidence. (Circular Pond Marshes.)
5th. Norfolk Plains. — Here the lowest strata are siliceous breccia, resting on a greenstone base: on these lies gritstone and fragmentary argillaceous rock of slaty structure, in an inclined position. The limestone next above is flaggy, and the beds nearly horizontal: it contains the following fossils : —
This limestone is covered by a conglomerate in horizontal beds, visibly indurated by the action of heat.
6th. Ben Lomond on the N. E., and Ben Nevis on the S., show this group in the following ascending succession. First, siliceous breccia, composed of fragments of mica slate, argillaceous and siliceous slate; then greywacke; next, compact claystone; and lastly, compact limestone without fossils: the whole crowned by immense masses of greenstone, which are seen thrust between the members of the group and mica slate, and rising on the granitic base to the height of 5000 feet. In the eruption of the greenstone which constitutes the dentiform crest of Ben Nevis, the lower members of the series (the siliceous breccia and clay slate) were disjoined, and carried to the height of 3200 feet, where they are found lying on the neck which unites Ben Nevis with Ben Lomond.
7th. Break-o'-Day Valley, East. — A westerly section from St. Patrick's Head, beginning with the sienitic axis of the chain, furnishes the following members to the series: granular quartz rock, greywacke, gritstone, clay slate, clay stone, and massy and slaty limestone, with the following fossils: —
This limestone is in a few instances overlaid by a conglomerate. The whole group, with the exception of the limestone and conglomerate, is thrown in a very inclined position by the greenstone of St. Patrick's Head, which greenstone burst up between it and the sienitic axis.
8th. The sources of the river Nive, in the Upper Country, and the locality east of Marlborough, exhibit perhaps the most complete section of this group that is to be seen. Here a massy fossiliferous limestone abuts against a very inclined argillaceous and siliceous slate: upon this limestone rests a slaty fragmentary rock without fossils; a fossiliferous, arenaceous, and argillaceous massive rock, with somewhat of a slaty fracture, follows. This is crowned by a sedimentary deposit of mud and fine sand, which reaches an elevation of 5200 feet. The series in this locality contains the following fossils: —
Spirifer subradiatus, and S. Stokesii.
Fenestella internata, and F. ampla.
9th. Eastern Marshes. — Greywacke with a slaty cleavage forms here a highly inclined base, on which rests a compact massive limestone, containing
This limestone is covered unconformably by conglomerate, which is much worn away. The eruption of the greenstone which now separates the tributaries of Little Swan Port from those of the Tamar river does not seem to have affected the position of the limestone.
10th. Mount Dromedary; Mount Wellington; Grass Tree Hill.— The limestone of this locality is both mineralogically and geologically similar to that of the Eastern Marshes, and the sources of the river Nive: it contains the following fossils : —
The position of the two fossiliferous members of the group, on the east side of Mount Wellington, above Mr. Hull's house, as also the position of the conglomerate on the top of Mount Wellington, is owing to the eruption of the greenstone of that locality, by which the above-named members of the series were disjoined, and elevated far above the rest. 11th. Spring Hill, West.—A fossiliferous greywacke, with
is the only member of the rocks belonging to the second epoch which is found in this locality. Its position relatively to the subjacent strata is difficult to be determined with accuracy, on account of the prevailing dislocations.