This is contrary to what might have been expected, for if the crystals had been originally disseminated in equal numbers, the greater intumescence of this lower scoriaceous part would have made them appear fewer in number.
In most cases, where a stream of lava has flowed down a valley, it is bounded on each side by loose scoriaceous masses.
The cells of the scoriaceous basalt are lined or filled with fine, concentric layers of chalcedony, coated and studded with bright-red oxide of iron.
The successive sheets are either closely united together, or are separated from each other by beds of scoriaceous rock and of laminated tuff, frequently containing well-rounded fragments.
The jasper is of an ochre yellow or red colour; it occurs in large irregular masses, and sometimes in veins, both in the altered trachyte and in an associated mass of scoriaceous basalt.
The scoriaceous fragments and the calcareous matter are associated in the most irregular manner, sometimes in obscure beds, but more generally as a confused breccia, the lime in some parts and the scoriae in others being most abundant.
Other fragments of the scoriaceous rock from this hill, when broken, are often seen marked with short and irregular white streaks, which are owing to a row of separate cells being partly, or quite, filled with white calcareous powder.
A second stream was only eight inches thick, including both the upper and lower scoriaceous surfaces.
Slaggy and scoriaceous phases are common, but probably represent only a small part of the different flows.
The granite, however, exhibits no intrusive characters, while the overlying andesite becomes scoriaceous in its lower portion, although compact immediately above.
In some of the amygdaloidal traps of Scotland, where the nodules have decomposed, the empty cells are seen to have a glazed or vitreous coating, and in this respect exactly resemble scoriaceous lavas, or the slags of furnaces.
They also differ in never being scoriaceousor amygdaloidal, and never forming a porphyry with an uncrystalline base, or alternating with tuffs.
Scoriaceous lava in part converted into an amygdaloid.
In the foreground is the main lava stream with scoriaceous surface (after W.
Scoriaceous lava encroaching upon the tracks of the Vesuvian railway (after a photograph by Sommer).
A quite different type is the block lava (Aa type) which usually has a raggedscoriaceous surface and consists of more or less separate fragments of cooled lava (Fig.
At last we emerged from the ice-bound region to find ourselves on scoriaceous lava, coated in places with a thin layer of a loamy deposit.
These are extinct volcanoes covered with brown scoriaceous lava, and the craters are well-marked depressions, though in each case there is a gap in the side through which much of the lava must have flowed.
A more difficult piece of measurement could not be imagined, taken as the line was over the extremely rough surface of a broken-up scoriaceous lava-field.
On the surface in this locality there also occur basic agglomerates containing scoriaceous rocks, the products of some of the last stages of volcanic action in this part of the island.
The rocks of this ancient volcanic mountain are almost all of the massive basic type, and except at the mouth of the Ndriti Gap hardly ever display a scoriaceous character.
The larger are angular or sub-angular, and are composed of hemicrystalline basaltic andesites, scoriaceous and vesicular and sometimes amygdaloidal.
At and near the mouth of the Narengali valley there are exposed basic tuffs and agglomerates, the blocks in the last case being formed of a semi-vitreous, vesicular or almost scoriaceousbasaltic andesite.
The other is a scoriaceous rock containing numerous round steam-pores, ranging up to 5 millimetres in diameter and generally filled with clear quartz-crystals and lined by chalcedony.
This inference is also supported by the occasional scoriaceous character of the rocks below referred to.
In one place I came upon such a bed 12 feet thick, compact in its upper half and slaggy or scoriaceous in its lower half.
One of the blocks was composed of a highly scoriaceous semi-vitreous rock, the cavities being filled with a zeolite.
These rocks come near to the non-porphyritic group of genus 9; but differ in the absence or rarity of plagioclase phenocrysts, in their more frequently vesicular and scoriaceous character, and in the fresher condition of the rock.
Half an hour after leaving the "Blessed Valley" we came to a huge flight of steps roughly cut in a long broad line of black scoriaceous basalt.
To the South-west the plain is bounded by ridges of scoriaceous basalt, and by a buttress of rock called Jabal Ayr, like Ohod, about three miles distant from the town.
The walls, which were perfectly vertical, and disposed like masonry in a very regular manner, were composed of a brown-colored scoriaceous lava, similar to the light scoriaceous lava of Mt.
By measurement, the river above is 870 feet wide, immediately contracted at the fall in the form of a lock, by jutting piles of scoriaceous basalt, over which the foaming river must present a grand appearance at the time of high water.
A little higher up the creek its banks are formed by strata of very heavy and hard scoriaceous basalt, having a bright metallic lustre when broken.
The central cone of Jorullo is still burning, and on one side has thrown up an immense quantity of scoriaceous and basaltic lavas, containing fragments of primitive rocks.
The pinnacles known as "Rabbit Ears," above the prominent talus in figure 15, are of vent breccias that consist mostly of welded blocks of scoriaceous basalt, but also contain volcanic bombs which were blown out as blobs of fluid lava.
The thin irregular scoriaceous andesite flows, which are exposed in the cliffs east of Little Strawberry Lake adjoining the plug, contrast strikingly with the massive even flows of the Picture Gorge Basalt.
When the igneous rock itself is examined, its upper portions are often observed to be scoriaceous or cinder-like, and the under portions likewise frequently exhibit a similar appearance.
Thus, in most cases, a bed of lava is scoriaceous as well below as above.
Presently the mules encountered some pretty bad going, on a steep slope covered with huge lava boulders and scoriaceous sand.
We climbed slowly around the lower spurs of Coropuna into a bleak desert wilderness of lava blocks and scoriaceous sand, the Red Desert, or Pampa Colorada.
Among the ruins we found a number of broken stone dishes, rudely carved out of soft, highly porous, scoriaceous lava.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "scoriaceous" in a variety of sentences. We hope that you will now be able to make sentences using this word.
