Sandstone

“ Whoever has rambled much in a coal-country, scrambling through briars and brambles in old quarries, or threading his way among the rocks of river-courses, must often have noticed, on the exposed surface of sandstone blocks, dark ribbon-like bands fretted over with little diamond-shaped knobs. They are so common in some districts, that you can scarcely light upon a piece of sandstone which does not show one or more. ”

“ In this variety we have sometimes observed the lead ore either disseminated, or forming horizontal veins between the laminæ of sandstone. An examination of some spots might lead to the conclusion that the soil in which most of the lead has hitherto been found, has resulted from the disintegration of a sandstone of this kind.
Sandstone, though often covered at the surface by compact limestone or some other stratum is probably the rock which occurs in the greatest quantity throughout every part of this range of mountains. ”

“ Earth-stresses and shrinkage give rise to joints in sandstone, which may not be so clean and sheer as those in limestone, but which affect even the softer - 69 - forms. Cemented sand-dunes of modern date tend to break away along vertical planes. Firmer sandstones give rise to stepped table-lands and "edges," and the resistance of many types to atmospheric decay renders their stratified structure strongly apparent. ”

“ The sandstone pillars generally taper from the base upwards to a short distance from the tops, which are flattened out or surmounted by slabs or blocks of sandstone 90 of fantastic outline, and they are called by names derived from fancied likenesses to animals, birds, and men. The juxtaposition of the most brilliantly hued, dazzling-red blocks and strata, with masses of the same material of milky whiteness, gives the impression that the scene is the work of human hands; it seems too quaint and artificial for the hand of Nature, to which alone it is due ”

“ The indurated sandstone is of a yellowish grey colour, dense, compact and ponderous; it consists essentially of fine grains of quartzy sand and silvery mica, and contains very slender imperfect veins of calcareous spar, and small irregular granular concretions of ferriferous carbonate of lime: these concretions decompose by exposure to the air, and give the external surface of the stone a brownish yellow ochry tinge. ”

“ NEW RED SANDSTONE. A large series of reddish-colored loams, shales, and sandstones, occurring between the Carboniferous and the Middle Triassic formations, were grouped together under this name, in contradistinction to the Old Red Sandstone group, which lies below the coal measures, and has a similar mineral structure. ”

“ The sandstone is of the coarsest quality, almost a conglomerate, and is soft and friable; exposure to the air might probably harden it if quarried, when it would be available for rough building. The ridges, with very few exceptions, are topped with large blocks of ferruginous sandstone, irregularly cast about, and are covered with a thick scrub, laced and woven together with a variety of vines and climbers, while the small valleys intervening bear a strong growth of tall grass, through which numerous creeping plants twine in all directions, some of them bearing beautiful flowers. ”

“ Such ripple-marked sandstone is far from uncommon. It gives a perfect reproduction of the little sand-ripples or rounded ridges and hollows, often to be found on a sandy shore, either visible through a thin layer of water or left bare after the tide goes down. And it shows us how the sandstone rock must originally have [p. 126] been put together, under water. Soft undulations were made in the wet sand by one high tide, becoming in a measure hardened before the next high tide, and so keeping their shapes, while a fresh supply of sand was dropped upon them, partaking of the same outlines. ”

“ The black rock has given place to a very soft sandstone, which seems to be washed away fast by the river, and being thrown into the river renders its navigation more difficult than it was yesterday: above this sandstone, and towards the summits of the hills, a hard freestone of a yellowish brown colour shows itself in several stratas of unequal thickness, frequently overlaid or incrusted by a thin stratum of limestone, which seems to be formed of concreted shells. ”

“ In Northern Kharga we find two similar but distinct sandstones, separated by a 75-metre band of Impermeable Grey Shale. The upper bed, which we have for convenience designated the ‘Surface-water Sandstone,’ is exposed at the surface, and contains standing or sub-artesian water; while the lower, from which the flowing wells derive their supplies, never approaches within 80 metres of the surface, and forms the true ‘Artesian-water Sandstone.’ It will be convenient to give these sandstones separate consideration. ”

“ The sandstone predominates in some parts of the range, forming small cliffs, underneath which there are steep acclivities of sand. It contains nearly an equal quantity of black flinty slate, or lydian stone, and white quartz in its composition, and greatly resembles the friable sandstones of the lignite formation at the mouth of Bear Lake River. 186In some parts the soil has a red colour from the disintegration of a reddish-brown slate-clay. ”

“ All over the face of the hill there are masses of this hard pebbly sandstone cropping up, though they are not so noticeable as the so-called Devil's Stone because they are flat and occasionally crumbling, and have not had their sides laid bare by energetic treasure-seekers. ”

“ In attempting to descend the creek from our last encampment, we found the valley so obstructed with fragments of greenstone as to be wholly impassable. We accordingly ascended into the plain; and continuing along on the brink of the precipice, arrived in a few hours at a point where the substratum of sandstone emerges to light at the base of an inconsiderable hill. It is a fine gray sandstone, having an argillaceous cement, and its lamina are so nearly horizontal, that their inclination is not manifest to the eye. ”

“ As building stones sandstones are much in favour, especially in the Carboniferous districts of Britain, where they can readily be obtained. They have the advantage of being durable, strong and readily dressed. They are usually laid “on the bed,” that is to say, with their bedding surfaces horizontal and their edges exposed. The finer kinds of sandstone are often sawn, not hewn or trimmed with chisels. Pure siliceous sandstones are the most durable, but are often very expensive to dress and are not obtainable in many places. Sandstones are also used for grindstones and for millstones. ”

“ Most of the remarks written on diaspore apply as well to burley clay.
Sandstone
Sandstone is a rock made of sand-size particles more or less well cemented. It is recognized by the grains of sand which are dislodged or scratched loose when the rock is broken, or when scraped with a piece of steel or another hard rock. The old-fashioned grindstone is a sandstone nicely cemented by nature. ”

“ The surface of the sandy plain rises perceptibly towards the base of the mountains; and becoming constantly more and more undulating, is at length broken, disclosing some cliffs and ledges of micaceous {280} sandstone. Near the Platte this sandstone occurs in horizontal strata, sometimes divided by the beds of the streams, and forming low ridges parallel to the Rocky Mountains. Whether they continue in an uninterrupted line along the base of the mountains, we have not been able to ascertain. ”

“ The sandstone seemed often argillaceous or marly, and in some cases seemed to contain beds of hard grey gritstone and ferruginous concretions. In lithological character it resembled a good deal the new red sandstone of England. I never found any fossils in it, but it appeared every where to be horizontal and conformable to the white limestones and sands above it. These latter are certainly tertiary, as they in some places contained shells of the genera area and venus apparently of species now existing on the coast, and certainly of very recent and unaltered aspect. ”

“ In the deeper valleys, towards the eastern edge of these sandstones thin beds of oolitic limestone, containing numerous fossil shells, occasionally occur; also gypsum and clayey shales, with other indications of the probable existence of coal in the vicinity; following the series appears a compact, fine-grained amorphous sandstone, having an almost flinty fracture; this rock, in a few miles, gives place to granite and gneiss, frequently broken up by the upheaval of whinstone and porphyritic trap hills, having an elevation of from 100 to 500 feet above the plain. ”

“ Sandstone rocks stand up in it at various points like islands, but all are metamorphosed, and branches have flowed off from the igneous sea into valleys and defiles, and one can easily trace the hardening process of the fire as less and less, till at the outer end of the stream the rocks are merely hardened. ”

“ In nature there is every intermediate gradation, from perfectly loose sand, to the hardest sandstone. In micaceous sandstones mica is very abundant; and the thin silvery plates into which that mineral divides, are often arranged in layers parallel to the planes of stratification, giving a slaty or laminated texture to the rock.
When sandstone is coarse-grained, it is usually called grit. If the grains are rounded, and large enough to be called pebbles, it becomes a conglomerate, or pudding-stone, which may consist of pieces of one or of many different kinds of rock. ”

“ Slabs of sandstone and shale often retain what is called the ripple-mark—that is, the corrugation of surface produced by the gentle agitation of shallow water over sand or mud. We can see these appearances beneath our feet, as we walk over the pavement of almost any of our cities. ”

“ Whether it be granite, porphyry, trap of any kind, or limestone, the result is the same. Sandstone is, perhaps, the least friable amongst the several varieties of rock. Let any one scramble up the sides of a hill formed of granite, porphyry, or limestone, and he will find everything give way under his feet. If the side be pretty steep he will experience the not very agreeable sensation of treading upon a heap of loose cinders. ”

“ A single drop of water, constantly falling, will hollow out a stone. In these millions of years the water has swept away rocks here, and formed new land by the accumulation of sand there. In these millions of years the sand has been compressed into the gigantic masses that tower above us to-day as sandstone mountains; they are formed of sand that was originally laid like mud, layer by layer, on the floor of the ocean. ”

“ I have said that the flat promontory occupied by the ruin is edged by hills of indurated sand. Existing in some places as a continuous bed of a soft gritty sandstone, scooped wave-like a-top, and varying from five to eight feet in thickness, they form a curious example of a sub-aërial formation,—the sand of which they are composed having been all blown from the sea-beach, and consolidated by the action of moisture on a calcareous mixture of comminuted shells, which forms from twenty to twenty-five per cent. ”

“ The Upper Old Red Sandstone, composed of red sandstone and conglomerates, is only sparingly developed. The strata occur on the east shore between the Fallen Rocks and Corrie, and they appear along a narrow strip to the east and south of the lower division of the system, between Sannox Bay and Dougrie. ”

“ Cliffs of "Desert Sandstone" resting on granite and porphyry, and repeated by faults. I have already spoken of the general contrast between the two sides. The eastern side is the grander and more striking of the two, except close to the Gulf of Akabah, where both sides are formed of granite and porphyry, rising into bold and rugged ridges. On the western side these rocks soon pass below beds of sandstone, followed by others of limestone, which break off in steep escarpments with grand headlands and bastions. ”

“ The idea that trees can flourish on sandstone soils because they require nothing from the soil itself is of course erroneous. They depend to a large extent upon the materials set free by the decay of certain grains, or of the cement of the underlying sandstone. In proportion as the sandstone is impure, that is, the more its constituents deviate from pure quartz, the more chance there is that it will provide a fertile soil. ”

“ We come to a bare part of the ravine where brushwood and herbage find but a scanty footing and where accordingly the rocks can be attentively studied. The face of the escarpment shows a number of beds of pale grey sandstone alternating with courses of a dark crumbly shale. The sandstones being harder and firmer in texture stand out in prominent relief while the shales between have been wasted away, covering the bottom of the slope with loose debris. ”

“ At our feet were the clean and well-washed pebbles, borne upward into tiny lines and heaps by the restless surf. A search amongst these would reveal to us the material of the mountain heaps which rose behind and on our right and left; there was schist, conglomerate sandstone, a hard white clay, an ochreish clay containing much iron, polished quartz, &c. Looking out of our tent, we could see a line on each side of us of thick tall reeds, which form something like a hedge between the beach and the cultivated area around Niasanga. ”

“ The sandstones of the Narrows lie in horizontal beds, and have generally a dark gray colour. They are parted by thin slaty beds of sandstone, containing small pieces apparently of bituminous coal, and some casts of vegetables. Most of the beds contain scales of mica, and some of them have nodules of indurated iron-shot clay which exhibit obscure impressions of shells. A bed of imperfectly crystalline limestone was seen by Captain Franklin underlying the sandstones. ”