Rift valley, overlying a formation of granite, gneiss and quartz.
The Cordillera, which bounds them on the west, is formed of folded beds, while the Sierras which rise in their midst, consist mainly of gneiss, granite and schist.
The rocks of its lower half are mainly granite and gneiss; its upper half is composed of porphyritic greenstone, and a variety of minerals occur.
Granite is the most widely spread of the crystalline rocks; but dikes of various kinds occur, and gneiss, schist and marble are also met with.
Ungava includes much of the lower portion of Labrador, with a rim of recent marine deposits along its western coast, but the interior has the usual character of low rocky hills of Archean rocks, especially granite and gneiss, with a long band of little disturbed iron-bearing rocks, resembling the Animikie, or Upper Huronian of the Lake Superior region, near its eastern side.
The most valuable immediate product of the state's mines and quarries for nearly every year from 1890 to 1908 was building stones of granite and gneiss, which are found in all parts of the state west of the " Fall Line "; the best grades of granite are quarried chiefly in Gaston, Iredell, Rowan, Surry and Wilkes counties.
- The Somaliland plateau is chiefly composed of gneiss and schist.
Nearly the whole of the Riesenkamm and the western portion of the southern chain are granite; the eastern extremity of the main ridge and several mountains to the south-east are formed of a species of gneiss; and the greater part of the Bohemian chain, especially its summits, consists of mica-slate.
Laurentian gneiss forms the greatest mass of the exposed rocks of the country bare of ice.
It is possible that some of these rocks are also of Huronian age, but it is doubtful whether the rocks so designated by the geologists of the " Alert " and " Discovery " expedition are really the rocks so known in Canada, or are a continuous portion of the fundamental or oldest gneiss of the north-west of Scotland and the western isles.
Large sheets of muscovite, such as are of commercial value, are found only in the very coarsely crystallized pegmatite veins traversing granite, gneiss or micaschist.
Bergeron has shown that the gneiss and schist which form so much of the chain consist, in part at least, of metamorphosed Cambrian beds.
- Geologically Venezuela consists of three distinct regions: (1) South of the Orinoco a great mass of granite, gneiss, pyroxenite and other crystalline rocks, continuous with that of Guiana and probably of Archean age.
Rising amid the ancient gneiss rocks of the St Gotthard, the Rhine finds its way down to the Lake of Constance between layers of Triassic and Jurassic formation; and between that lake and Basel it penetrates the chalk barrier of the Jura.
The upper Rhenish valley is evidently the bed of an ancient lake, the shores of which were formed by the gneiss and granite of the Black Forest on the one side and the granite and sandstone of the Vosges on the other.
Gneiss and granite occur; Ordovician fossils have been found in the Upper Shan States, and Carboniferous fossils in Tenasserim and near Moulmein.
This authority sums up the geology of Japan briefly and succinctly as follows (in Things Japanese, by Professor Chamberlain): The backbone of the country consists of primitive gneiss and schists.
Bismuth occurs in metalliferous veins traversing gneiss or clay-slate, and is usually associated with ores of silver and cobalt.
Archean rocks - gneiss, schist and granite - cover large areas through which the Nile cuts its way in alternate narrow gorges and open reaches.
West of the volcanic region, nearer to Lake Victoria and the Eastern province, ironstone, granite, gneiss and schistose formations predominate, with phonolite in places.
In the Eastern province the rocks are mainly quartz, gneiss and granite, with sandstone in Busoga, basalt round Mt Elgon, slate (Busoga) and iron- g stone (Busoga and Bukedi).
Gneiss, granite and quartz - the decomposed granite giving the red " African " clay - are the leading features in the formations of the Northern province, of Buganda, and of the Western province, with some sandstone in the littoral districts of Buganda and in Ankole, and eruptive rocks.
Of the Red river valley granite and gneiss are found, but these materials are not quarried.
Graphite occurs mainly in the older crystalline rocks - gneiss, granulite, schist and crystalline limestone - and also sometimes in granite: it is found as isolated scales embedded in these rocks, or as large irregular masses or filling veins.
The graphite found in granite and in veins in gneiss, as well as that contained in meteoric irons, cannot have had such an origin.
Alluvial loams occupy the narrow river valleys; but the most common soil of the section is that formed from gneiss with a large per cent.
They consist of gneiss, mica-schist, quartzites, crystalline limestones and conglomerates.
Along with these, similarly, hornblende and diabase occur in the Pelew Islands and gneiss and mica 1 These are dependencies of New Zealand, as are also the following islands and groups which lie apart from the main Polynesian clusters, nearer New Zealand itself: Antipodes Islands, Auckland Islands, Bounty Islands, Campbell Islands, Chatham Islands, Kermadec Islands.
In the mountain region the soil is mostly a sandy loam composed of disintegrated granitic gneiss and organic matter; on the lower and more gentle slopes as well as in the valleys this is generally deep enough for a luxuriant vegetable growth but on the upper and more precipitous slopes it is thin, or the rocks are entirely bare.
Minerals.-The most important of the mineral products of New Hampshire, which has long been known as " the Granite State," is granite, which is quarried in the southern part of the state in the area of " Lake Winnepesaukee gneiss," near Concord, Merrimack county, near Milford, Hillsboro county, and E.
Geologically, they have also been differentiated as the Gneiss Islands and the Trap Islands.
The Outer Hebrides being almost entirely composed of gneiss the epithet suitably serves them, but, strictly speaking, only the more northerly of the Inner Hebrides may be distinguished as Trap Islands.
Becket gneiss 2000 ft.(?)
Washington gneiss 2000 ft.(?)
This vast area, shaped like a broad-limbed V or U, with Hudson Bay in the centre, is made up chiefly of monotonous and barren Laurentian gneiss and granite; but scattered through it are important stretches of Keewatin and Huronian rocks intricately folded as synclines in the gneiss, as suggested earlier, the bases of ancient mountain ranges.
The several ranges of the Cordillera show very different types of structure and were formed at different ages, the Selkirks with their core of pre-Cambrian granite, gneiss and schists coming first, then the Coast Ranges, which seem to have been elevated in Cretaceous times, formed mainly by a great upwelling of granite and diorite as batholiths along the margin of the continent and sedimentary rocks lying as remnants on their flanks; and finally the Rocky Mountains in the Laramie or early Eocene, after the close of the Cretaceous.
The configuration of the hills is mainly conical and the geological formation consists of gneiss, granite (in the south) and red sandstone.
As in the neighbouring mainland of Caithness, these rocks rest upon the metamorphic rocks of the eastern schists, as may be seen on Pomona, where a narrow strip is exposed between Stromness and Inganess, and again in the small island of Graemsay; they are represented by grey gneiss and granite.
Gneiss & Mica Schist A-G.
Augen Gneiss Schmidt Ter.
The foreign boulders of granite, gneiss, &c., found in the coalmeasures of some districts, are quite as likely to have been dropped by rafts of vegetation as to have been carried by floating icebergs.
The oldest rocks are gneiss, schist and quartzite, the schist often containing gold.
Among the commonest associates of the diamond are quartz, topaz, tourmaline, rutile, zircon, magnetite, garnet, spinel and other minerals which are common accessory constituents of granite, gneiss and the crystalline schists.
They consist chiefly of gneiss and schist, with granite and other eruptive rocks.
Between the Palaeozoic area near Ottawa, and Georgian Bay to the north of the region just referred to, there is a southward projection of the Archaean protaxis consisting of granite and gneiss of the Laurentian, enclosing bands of crystalline limestone and schists, which are of interest as furnishing the only mines of "Old Ontario."
Their geological formation is metamorphic gneiss, veined with felspar and quartz, and interspersed with reddish porphyrite.
The Monti Peloritani at the north-eastern extremity of the island consists of gneiss and crystalline schists; but with this exception the whole of Sicily is formed of Mesozoic and later deposits, the Tertiary beds covering by far the greater part.
The island is composed of marble, though gneiss and mica-schist are to be found in a few places.
It is composed of gneiss, is generally rather flat, save in the west where Ben Hogh reaches a height of 339 ft., and has several lakes.
Dispersed over all parts of the western Highlands, they are most numerous in the north-west, especially in the Outer Hebrides and in the west of the shires of Ross and Cromarty and Sutherland, where the surface of the Archean gneiss is so thickly sprinkled with them that many tracts consist nearly as much of water as of land.
Archean gneiss, Cambrian sandstone, Silurian quartzite, limestone and schist, Jurassic sandstone and limestone, Cretaceous sandstone, and Tertiary basalts, gabbros, and granitic rocks all enter into the composition of the islands.
Eastward of the Archean gneiss in the west of Sutherland the effect of enormous underground pressure has been to upraise masses of the ancient gneiss and Torridonian sandstone and thrust them westward over the younger rocks.
Above the Archean gneiss lies a series of red and chocolate-coloured sandstone (Torridon sandstone), which form a number of detached areas from Cape Wrath down the seaboard of the shires of Sutherland and Ross and Cromarty, across Skye, and as far as the island of Rum.
In descending order they embrace the following subdivisions, whose thickness in the district of Durness is estimated at about 2000 ft.: (e) limestones, dolomites and cherts, with numerous organic remains; (d) grit and quartzite, with Saltarella and Olenellus (Serpulite Grit); (c) calcareous shales and dolomites, with many annelid casts and sometimes Olenellus (Fucoid Beds); (b) Upper Quartzite, often crowded with annelid pipes (Pipe Rock Quartzite); (a) Lower Quartzite - their original upper limit can nowhere be seen, for they have been overridden by the Eastern Schists in those gigantic underground disturbances already referred to, by which these rocks, the Archean gneiss and Torridonian sandstone, were crumpled, inverted, dislocated and thrust over each other.
High, "some like gigantic tusks, some like sugar-loaves, and some like vast stalagmites," but all consisting of iron-grey or reddishbrown conglomerate of gneiss, mica-slate, syenite and greenstone.
The Eastern Cordillera is composed of gneiss, mica and chlorite schist and other crystalline rocks of ancient date; the Western Cordillera, on the other hand, is formed of porphyritic eruptive rocks of Mesozoic age, together with sedimentary deposits containing Cretaceous fossils.
The oldest rocks consist of gneiss and schist, penetrated by dikes and bosses of granite, syenite, porphyry and other intrusive rocks.
These mountains, consisting of various sorts of gneiss, intrusive granite and gabbro, have been formed partly by faulting but mainly by erosion, the lines of which have been determined by the presence of faults or the presence of relatively soft rocks.
In the south, where they are known as the Dharwar series, they form long and narrow bands running from north-north-west to south-south-west across the ancient gneiss; and it is interesting to note that all the quartz-reefs which contain gold in paying quantities occur in the Dharwar series.
The Finland rappa-kivi, the Serdobol gneiss, and the Pargas and Rustiala marble (with the so-called Eozoon canadense) yield good building stone; while iron, copper and zinc-ore are common in Finland and in the Urals.
Large ore-bodies of granular and compact magnetite occur as beds and lenticular masses in Archean gneiss and crystalline schists, in various parts of Norway, Sweden, Finland and the Urals; as also in the states of New York, New Jersey, Pennsylvania and Michigan, as well as in Canada.
In thickness, occupying undulating hollows in the underlying gneiss, and dip towards the Noursoak Peninsula at 20°, when the overlying Atanakerdluk strata come in.
The oldest rocks of this region consist of gneiss, granite and other crystalline rocks.