You will readily see from what has been said why shales, sandstones, and limestones take the form of beds lying upon each other.
Underneath this member are nearly 1,000 feet of the Lower Aubrey sandstones, displaying an intensely brilliant red, which is somewhat masked by the talus shot down from the gray, cherty limestones at the summit.
These are succeeded by an apparently conformable succession of beds of still younger age, culminating in a series of shales, sandstones, and limestones of unmistakably Triassic age.
Here, as in many parts of North-Western India, the Nummulitic limestones are associated with coal which has been largely worked.
The Aymestry limestone, which is irregular in thickness, is sometimes absent, and where the underlying Wenlock limestones are absent the shales of the Ludlow group graduate downwards into the Wenlock shales.
While of the Silurian coral limestones of the Arctic regions he says: "The formation of thick strata of limestone shows that life like that of the lower latitudes not only existed there, but flourished in profusion.
In fact coral limestones of the Carboniferous system are the nearest known fossiliferous rocks to the North Pole, and from the strike of the beds must underlie the Polar Sea.
Their line of contact with the massive gray limestones of the overlying Castle Mountain group is well seen near the entrance of the gap in the hills to the north.
Limestones and slates with Silurian corals and other fossils have been found in Sze-ch'uen.
In this region it consists of a lower series of limestones and an upper series of sandstones with seams of coal, which may perhaps be in part of Permian age.
They consist of harder sandstones and limestones interstratified with softer clays and shales.
Calabria and a similar rock occurs in Sicily, Bosnia, Epirus, Corfu; in Spain the Liassic strata are frequently dolomitic; in the Apennines they are variegated limestones and marls.
In general, Oriel and Tracey (1970) have found that buff limestones prevail to the north and white, siliceous limestone, to the south.
Chemical and organic processes formed limestones and marlstones in the deeper central part of the lake.
In those areas where the member represents a deep-water environment, organically formed limestones and shales are predominant.
Jurassic rocks, including the Estuarine Lower Oolite sandstones, shales and limestones and Middle Oolite Oxfordian rocks are found in the north of this island; there is also a small trace of Upper Cretaceous sandstone.
Then follows a mass of dolomite and unbedded limestones containing Hippurites and evidently of Upper Cretaceous age.
It had never enabled the Germans to master the Ypres salient, and as the autumn showed, its conquest made no serious gap in the strength of the German defences.
But if it resulted in serious losses, it brought some additions to our gains of ground.
It looked as though winter might come with the line of battle much where it was before the German offensive began in March.
Jukes-Browne and Harrison ascribe the Scotland beds to the Eocene or Oligocene period, the Oceanic series to the Miocene, the Bissex Hill marls to the Pliocene, and the coral limestones partly to the Pliocene and partly to the Pleistocene.
The limestones contain Globigerina and other Foraminifera, the siliceous beds are made of Radiolaria, sponge spicules and diatoms, while the red clay closely resembles the red clay of the deepest parts of the oceans.
Below these is a monotonous succession of shales, practically unfossiliferous, with occasional quartzites and limestones representing the Upper and Middle Jurassic with at the base beds probably belonging to the Lias.
The Cretaceous-Eocene limestones form comparatively narrow bands, occurring as compressed synclines caught up in the folded complex of Jurassic shales.
Associated with the limestones and calc-gneisses are quartzites and tourmaline-biotite schists which probably represent the lowest portions of the shales immediately overlying the limestones.
Each group is made up of an alternation of soft marls or clays and hard limestones or sandstones.
In the same two areas we find the Silurian rocks, shales and limestones with grits and flags.
Devon is occupied by the Culm shales, limestones and grits of Carboniferous age.
Closely following the same line are the alternating clays and limestones of the Oolitic series.
The limestonesand shales are well exposed in Derbyshire, Yorkshire, Northumberland, the Mendip Hills and at Clifton.
All sorts of limestones are composed of more or less pure carbonate of lime.
The limestones should be laid upon wooden blocks to allow air to pass beneath them, while they must be guarded from dust both above and at the sides with sheets of paper.
Limestones which have developed fissures may, on immersion, lose small portions which might otherwise have remained attached, though probably for a while only.
If upon examination it is found that a drop of water softens the clay, the same line of treatment must be followed as in the case of limestones which exhibit a similar condition (see p.
Limestones which are much cracked, or which are likely to fall to pieces, should be wrapped round with gauze, or held together with twine, before they are put in the water.
The method formerly employed for the preservation of decaying and crumbling limestones was that of simple impregnation, and this is still followed in some cases which will be subsequently described.
Since chlorine compounds (especially common salt) form the predominating substance in the soluble salts contained in limestones their removal may be considered a proof that other salts (e.
For the treatment of limestones on which there are remains of colours the use of a solution of shellac, gum-dammar, or collodion is recommended.
The limestones were placed in tap-water in three glass cylinders, each containing 2 litres; the amount of silver solution required for the water was 0.
When limestones have been completely dried, especially if they are soft, it is often advisable to impregnate them with one or other of the impregnation agents.
The same difficulty which arose in the treatment of the Meten limestones was frequently met with in the treatment of these ostraca.
Overlying these more ancient rocks are limestones with Rhaetic and Liassic fossils, occurring in small patches at Oletta, Morosaglia, &c.
Cinto; but between the Gulfs of Porto and Galeria, schists, limestones and anthracite, containing fossils of Upper Carboniferous age, occur.
Veins and cavities inlimestones are usually lined with crystals of calcite.
Deposits of calamine have been extensively mined in the limestones of the Mendip Hills, in Derbyshire, and at Alston Moor in Cumberland.
They consist of dark grey and cream-coloured flagstones, sometimes thick-bedded with grey and blue shales and thin limestones and occasional intercalations of sandstone.
They consist of breccias, marls and limestones containing numerous fossils, and are for the most part Miocene but probably include a part of the Pliocene also.
They are succeeded unconformably by Eocene deposits, consisting of sandstones with coal-seams and limestones containing Nummulites, Alveolina and Orthophragmina; and these beds are as limited in extent as the Cretaceous schists themselves.
A peculiar structure found in the Arch\'91an limestones of Canada and other regions.
The lowest of the three divisions of the Jurassic period; a name given in England and Europe to a series of marine limestones underlying the O\'94lite.
A cement having the color of the Portland stone of England, made by calcining an artificial mixture of carbonate of lime and clay, or sometimes certain natural limestones or chalky clays.
Shales and limestones of this age are well seen along the railway near Changamwe.
Next above is the Cornbrash, a series of rubbly and occasionally hard limestones and thin clays.
The massive limestonesseparate generally into irregular blocks, tending to the form of cubes or parallelopipeds, and terminated by tolerably smooth planes.
We have already seen that there exists a marked distinction between those stratified rocks whose beds are amorphous and without subdivision, as many limestones and sandstones, and those which are divided by lines of lamination, as all slates.
Many limestones split along parallel planes, and may break into quite thin sheets on whose surfaces the flattened fossils show particularly well.
The deposits of the central, or Lycaonian, plateau consist of freshwater marls and limestones of late Tertiary or Neogene age.
Cretaceous limestones and serpentine take a large part in the formation of these mountains, while even the Oligocene is involved in the folds.
Limestones of Eocene or Cretaceous age form a large part of the Taurus, but the interior zone probably includes rocks of earlier periods.
Similarly, the occurrence of limestones suggests the existence of organic activity, but direct evidence is wanting.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "limestones" in a variety of sentences. We hope that you will now be able to make sentences using this word.
