Of the same age are the massive basalts of Jan Mayen, Spitzbergen, Franz-Joseph Land, and Greenland.
These basalts speak to us of prodigious fissure eruptions, when molten rock welled up along the lines of great cracks in the earth's crust, flooding wide regions, and building up enormous plateaux, of which we now behold the merest fragments.
It would appear that the great plateau-basalts of those regions, and of Iceland and the Faroee Islands, were contemporaneous, and were possibly connected with an important crustal movement.
To that date belong the basalts of Antrim, Mull, Skye, the Faroee Islands, and the older series of volcanic rocks in Iceland.
Many basalts are not columnar, and not a few columnar rocks are not basalts.
In fact, the lavas of Etna are very much the same in composition as the ordinary basalts of the British Isles, while those of Vesuvius are of a different type.
The nature of this contact, whether indicating the priority of the granophyres to the plateau-basalts or otherwise, is a matter of dispute between the two observers above named; but the circumstantial account given by Sir A.
Some basalts have a glass paste, or "ground-mass," in which the minerals are enclosed.
Before Werner had begun his teaching career at Freiberg, Desmarest, the French geologist, had made a special study of the basalts of Auvergne.
In the early years of the 19th century a great controversy convulsed the geological world as to the origin of the older basaltsor "floetz-traps.
Till recent years it was widely believed by continental geologists that the pre-Tertiary basalts differed so fundamentally from their Tertiary and recent representatives that they were entitled to be regarded as a distinct class.
Most nepheline basalts are fine grained, very dark coloured rocks, and belong to the Tertiary period.
Leucite-basalts contain small rounded crystals of leucite in place of plagioclase felspar.
Similarly there are leucite-basalts and leucite-basanites.
The distribution of basalts is world-wide; and in some places [v.
Even with the help of the microscope nepheline basalts are not always easy to determine, as the crystals may be exceedingly small and imperfect, and they readily decompose into analcite and zeolites.
Dolerites have a very wide distribution, as they are found wherever basalts occur in any number.
Transitions to the porphyritic dolerites and basalts arise by increase in the proportion of this ground-mass.
Large tilted slide blocks of the John Day Formation and basalts jumbled together show how important landsliding of soft beds under hard rocks can be in widening valleys.
These basalts are recognized by geologists to be of a distinct type, commonly called plateau or flood basalt.
Picture Gorge is narrow because the basalts in the walls are very resistant to weathering and break along vertical joints into large blocks that do not move easily.
C Local thickening of basalts and silicic volcanism in the Canyon City quadrangle, Oreg.
From Picture Gorge to the cliffs opposite, the Picture Gorge Basalts and varicolored ash beds of the John Day Formation rise together nearly 2000 feet.
Volcanic ashes, andesites, basalts and intrusive sheets of basic rock, mark an eruptive episode in the Carboniferous Limestone.
They are associated principally with basalts, nepheline and leucite basalts and monchiquites.
I see from your sketch that basalts of great thickness, and in some views beautifully columnar, do underlie the lignite bed; but I am not quite sure that these columnar basalts are those precisely which are called the Causeway.
I had never heard before that the Giant's Causeway rested on chalk, which all the basalts in your sketch do.
The basalts are submarine flows which formed the basis of the land upon which grew the vegetation which gave rise to the coals; the effusion of dolerite which covered up the Coal formation was subaerial.
As the rocks lie in a horizontal position, on most of the islands of the group only the basalts or dolerite are visible.
This rock of diorite is covered at its surface, by the effect of decomposition, with a yellowish crust, like that of basalts and dolerites.
This error on Werner's part was the less excusable, because, even before he began to lecture, the true nature of basalts and traps generally had been recognised by several observers of different nationalities.
Both basalts and trachyte contain more soda and less silica in their composition than granites; some of the basalts are highly fusible, the alkaline matter and lime in their composition acting as a flux to the silica.
The hydrated volcanic rocks, such as the basalts and trappean rocks in general, continue to produce effects of metamorphism, in which heat operates, although its influence is inconsiderable, water being much the more powerful agent.
These characters may be observed at the junction of the basalts which has been ejected upon the argillaceous strata near Clermont in Auvergne, at Polignac, and in the neighbourhood of Le Puy-en-Velay.
Besides the volcanic rocks mentioned there are intrusive basalts in the Carboniferous rocks like that in the neighbourhood of Shotts, and the smaller masses at Hogganfield near Glasgow and elsewhere.
If land predominated, the only monuments we are likely ever to find of Miocene date are those of lacustrine and volcanic origin, such as the Bovey Coal in Devonshire, the Ardtun beds in Mull, or the lignites and associated basalts in Antrim.
The two principal families of trappean or volcanic rocks are the basalts and the trachytes, which differ chiefly from each other in the quantity of silica which they contain.
Cordier found at Teneriffe xeolite in an amygdaloid which covers the basalts of La Punta di Naga.
These basalts were covered with a mammiform substance, which I vainly sought on the Peak of Teneriffe, and which is known by the names of volcanic glass, glass of Muller, or hyalite: it is the transition from the opal to the chalcedony.
Grenada, an ancient crater, filled with water; boiling springs; basalts between St. George and Goave.
The trachytes and basalts of Popayan are separated from the system of the volcanoes of Quito by the mica-slates of Almaguer; the volcanoes of Quito from the trachytes of Assuay by the gneiss of Condorasta and Guasunto.
The breccia contain fragments of the same basalts which they cover; and it is asserted that marine petrifactions are observed in them.
The basalts of Graciosa are not in columns, but are divided into strata ten or fifteen inches thick.
In Ireland the old basaltsare well seen at the Giant's Causeway, and on the Scottish coast we see them again at the well-known Fingal's cave at Staffa.
In Ireland the basalts attain a thickness of nine hundred feet; in Mull they are about three thousand feet thick.
The basalts of Saxony and Hesse, to which his observations were chiefly confined, consisted of tabular masses capping the hills, and not connected with the levels of existing valleys, like many in Auvergne and the Vivarais.
So early as 1768, before Werner had commenced his mineralogical studies, Raspe had truly characterized the basalts of Hesse as of igneous origin.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "basalts" in a variety of sentences. We hope that you will now be able to make sentences using this word.
