Quartzites Sentence Examples
Beginning in the south-east corner of the Gold Coast colony this range, composed of quartzites and schists, extends beyond the borders of Togoland into upper Dahomey.
The Falkland Islands consist entirely, so far as is known, of the older Palaeozoic rocks, Lower Devonian or Upper Silurian, slightly metamorphosed and a good deal crumpled and distorted, in the low grounds clay slate and soft sandstone, and on the ridges hardened sandstone passing into the conspicuous white quartzites.
The dark bituminous layers of clay slate, which occur intercalated among the quartzites, have led, here as elsewhere, to the hope of coming upon a seam of coal, but it is contrary to experience that coal of any value should be found in rocks of that age.
Many of the block mountains of the Great Basin are of complicated internal structure, showing rocks of all ages - slate, limestone, quartzites, granite, multi-coloured volcanic rocks, and large areas of lava overflow.
The quartz-schists consist of quartz and white mica, and are intimately related to quartzites.Advertisement
A group of highly inclined quartzites, altered conglomerates and jasperoid rocks which crop out on the Umhlatuzi river, between Melmoth and Nkandhla and on the White Umfolosi river above Ulundi Ph ins, is considered by Anderson to represent some portion of the Lover Witwatersrand series.
They show a great variety of type made up of slates, quartzites, occasional conglomerates, schists with large masses of intrusive granites and gneiss.
The lower group (Hospital Hill slates) consists of quartzites and shales, resting on the eroded surface of the older granites and schists, and estimated to be from 10,000 to 12,000 ft.
The upper group consists of conglomerates, grits and quartzites with a few bands of shales.
The individual beds, seldom more than a few feet in thickness and sometimes only a few inches, are interstratified with an immense thickness of quartzites.Advertisement
The conglomerate bands and quartzites contain large quantities of iron pyrites deposited subsequent to their formation, that in the conglomerates containing the gold.
The Black Reef Series is composed of quartzites, sandstone, slates and conglomerate.
The Pretoria Series, formerly known as the Gatsrand series, consists of repeated alternations of flagstones and quartzites, shales and sheets of diabase.
Sandstones, quartzites, conglomerates and breccia make up the formation.
They are often overlain by schists and quartzites, or broken through by volcanic masses.Advertisement
The geological formations thus exposed show that the plateaus are composed of a base of eruptive material, overlaid by enormous deposits of reddish sandstones, conglomerates and quartzites, exposed in parts to a depth of 2000 feet.
The value of the product of limestones and dolomites in 1900 was $124,728; in 1902, $228,662; of sandstones and quartzites in 1900, $37,038; in 1902, $165,565; while the value of all stone produced in 1907 was $497,962, and in 1908, $ 6 59,574.
In Karagwe certain quartzites, slates and schistose sandstones resemble the ancient gold-bearing rocks of South Africa.
This boss is bounded, except on the south, by the Witwatersrand series, the lower portion of which consists of quartzites and slates and the upper portion of quartzites and conglomerates.
The Black Reef series of quartzites and conglomerates and dolomite form a narrow outcrop resting unconformably upon the last-mentioned system.Advertisement
The total value of all mineral products in 1902 was $6,769,104, of which $6,464,258 were represented by gold and silver, $110,789 by sandstones and quartzites and $86,605 by limestones and dolomites; in 1908 the total value was $8,528,234, which was an i increase of more than $3,500,000 over the value in 1907.
They consist of gneiss, mica-schist, quartzites, crystalline limestones and conglomerates.
The highest beds, consisting of quartzites, shales, marls and sandstones with the remains of fucoids, are found in the Jurjura and Shellata.
In Wisconsin the inner lowland presents an interesting feature in a knob of resistant quartzites, known as Baraboo Ridge, rising from the buried oldland floor through the partly denuded cover of lower Palaeozoic strata.
A series of quartzites and slates referred to the Cambrian, and holding numerous and important veins of auriferous quartz, characterize its Atlantic or southeastern side, while valuable coal-fields occur in Cape Breton and on parts of its shores on the Gulf of St Lawrence.Advertisement
The wild and barren west of this county, including the great hills on Achill Island, is formed of "Dalradian" rocks, schists and quartzites, highly folded and metamorphosed, with intrusions of granite near Belmullet.
Traces of annelids have been detected in some of the quartzites, and some of the less changed parts of the limestones may be searched for fossils.
The quartzites rise in conical hills, such as those of Jura and Islay.
The quartzites themselves have also been subjected to extraordinary horizontal displacement, amounting in places to not less than Io m.
Rocks of Cambrian age have not been identified elsewhere in Scotland, though it may ultimately be shown that the quartzites and limestones of the Central Highlands are equivalents of those of the north-west coast.
Sandstones and quartzites were also quarried in 1902 in Albany, Crook and Uinta counties.
Thus, we find them more frequently, folded, tilted and cleaved; the muds have become shales, slates, phyllites or schists, the grey and red sands and conglomerates have become quartzites and greywackes, while the limestones are very generally dolomitized.
The Cambrian system is covered by his stages "B" and "C"; the former a barren series of conglomerates and quartzites, the latter a series of grey and green fissile shales 1200 ft.
In the Rennes basin limestones - often dolomitic - are associated with quartzites and conglomerates; silicious limestones also occur in the Sarthe region.
In Russian Poland is a series of conglomerates, quartzites and shales; some of the beds yield a Paradoxides fauna.
In the western and northern alpine part of Sweden, near the boundaries of Norway, the Silurian strata are covered by crystalline rocks, mica schists, quartzites, &c., of an enormous thickness, which have been brought into their present positions upon a thrust-plane.
The primary rocks which appear at Mitushev Kamen are overlaid with thick beds of quartzites and clayslates containing sulphide of iron, with subordinate layers of talc or mica slate, and thinner beds of fossiliferous limestone, Silurian or Devonian.
The rocks consist of sandstones, quartzites, slates and shales, associated with lenticular masses of limestone.
Granites and granodiorites were intruded at this period into the older rocks, and altered the adjacent Devonian beds into slates and quartzites, and formed gold-quartz veins, which have been worked in the Devonian rocks at Yalwal.
These are overlain, perhaps unconformably, by a great thickness of lavas and volcanic breccias (Pniel volcanic series, Beer Vley and Zeekoe Baard amygdaloids), and these in turn by the quartzites, grits and shales of the Black Reef series.
The chief rocks of the Campbell Rand series are limestones and dolomites, with some interbedded quartzites.
Among the Griquatown series of quartzites, limestones and shales are numerous bands of jasper and large quantities of crocidolite (a fibrous amphibole); while at Blink Klip a curious breccia, over 200 ft.
The Ongeluk volcanic series, consisting of lavas and breccias, conformably overlies the Griquatown series; while the grits, quartzites and conglomerates of the Matsap series rest on them with a great discordance.
The Bokkeveld beds are conformably succeeded by the sandstones, quartzites and shales of the Witteberg series.
Slates, schists, quartzites and limestones form the greater part of the hills, but the Brocken and Victorshohe are masses of intrusive granite, and diabases and diabase tuffs are interstratified with the sedimentary deposits.
The oldest rocks in this large area are a stratified series of mica-schists, limestones and quartzites, with numerous intrusive sheets of diorite, the whole having been metamorphosed by pressure, with frequent overfolding.
The quartzites here form bare white cones and ridges, notably in Errigal and Aghla Mt.
They are often contorted, and near the contact with the granite pass into mica-schists and quartzites.
In southeastern Wexford, in northern Wicklow (from Ashford to Bray), and in the promontory of Howth on Dublin Bay, an apparently earlier series of green and red slates and quartzites forms an important feature.
Towards the south-east, slates, quartzites and iron-bearing schists occur, but their age is not known.
The Mount Lyell schists which underlie the West Coast Range, and the quartzites of Port Davey on the western coast, have also been regarded as Archean.
The Ordovician system has not been certainly identified; but probably many of the slates and quartzites.
The Devonian system is best represented by the massive conglomerates and quartzites, which form the West Coast Range extending from Mount Lyell on Macquarie Harbour, through Mounts Jukes, Owen, Lyell, Murchison and Geikie, to Mount Black.
This includes a thin tract of Torridonian together with the overlying Cambrian quartzites.
These comprise quartzites, sandstones and shales that are exposed at the southern end of the Malvern Hills.
To the west Cambrian quartzites lie directly above the Ben More Thrust.
Upon a plinth of Torridonian sandstones lies the continuous cliff-line of bright white Cambrian quartzites.
The effect of Quinag on ice flow can be checked by measuring glacial striae on the quartzites.
The metamorphic rocks of the rest of Mainland are principally coarse gneisses, micaceous and chloritic schists, quartzites, &c.; in these rocks at Tingwall and Wiesdale considerable beds of limestone occur, which may be followed across the island in a northerly direction to Yell Sound, and to Dales Voe in Delting.
Low on the mountain the quartzites are scraped clean.