The Columbia plateau consists of horizontal beds of lava having a total thickness of several thousand feet, and its surface has a general elevation of tow to 2000 ft.
Over both sandstone and granite great sheets of lava have been poured, and these, protecting the softer beds beneath from further denudation, now stand up as the high plateaus and hills called harra.
Lava streams and other signs of volcanic action abound, but there has been no igneous activity since the Spaniards took possession.
Late in the Tertiary period vast sheets of lava poured from many points of the Great Dividing Range of eastern Australia.
There are raised coral beds high up the mountains, and lava occurs in a variety of forms, even in solid flows; but all active volcanic agency has so long ceased that the craters have.
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.
In the northern unfolded region great flows of basic lava lie directly upon the Cambrian and Ordovician beds of Siberia, but are certainly in part of Tertiary age.
Hauran southward forms the main watershed of the peninsula is covered in places by deep beds of lava, which from their hardness have preserved the underlying sandstones from degradation, and now stand up consider ably above the general level.
Volcanic cones still exist in large numbers, and the sheets of lava appear as fresh as any recent flows of Etna or Vesuvius.
Ence that any lava was emitted during this eruption.
Issuing from the tnks of the mountain, several streams of lava flowed down wards the west and south, and reached the sea at twelve or iirteen different points.
The modern cone of the mountain has been built up by suc~ssive discharges of lava and fragmentary materials round a Int of eruption, which lies a little south of the centre of the Tehistoric crater.
The numerous deep ravines which indented the des of the prehistoric volcano, and still form a marked feature I the outer slopes of Somma, have on the south side served channels to guide the currents of lava from the younger)ne.
An eruption in 1783, with a deluge of lava, destro~ed an extensive forest and overwhelmed several villages.
The rocks on the verge of the Kisumu province of East Africa are mainly volcanic (basalt, tuff, lava, kenyte).
In the Rudolf province there and are the basalt, lava, tuff and kenyte of the volcanic mineralogy.
And lava in south-western Ankole and on the eastern flanks of Ruwenzori.
But in the derivant valley peneplains developed in the present cycle of denudation, and there are residual summits also; in the Connecticut Valley trap ridges, of which Mt Tom and Mt Holyoke are the best examples; at Mt Holyoke, lava necks; occasionally in the lowlands, ridges of resistant sandstone, like Deerfield Mountain near Northampton; in the Berkshire Valley, summits of resistant schists, like Greylock, the highest summit in the state.
The earth surface above these natural furnaces has been hardened, cracked and sometimes melted into a reddish slag, called scoria, which, on account of its resemblance to lava, has given rise to an incorrect impression that the region was once the centre of volcanic disturbances.
The volcanic fissures that allowed of the upwelling of basalt are represented by numerous dykes, many cutting the earlier lava-flows as well as all the beds below them.
The accumulations of lava gave rise to the plateaus which form almost the whole interior of the county.
Hornaday, Camp Fires on Desert and Lava (London, 1908); Alex.
LAVA, an Italian word (from Lat.
Streams of rainwater, formed by condensation of exhaled steam often mingled with volcanic ashes so as to produce mud, are known as lava d'acqua, whilst the streams of molten matter are called lava di fuoco.
The magma, or molten lava in the interior of the earth, may be regarded as a mutual solution of various mineral silicates, charged with highly-heated vapour, sometimes to the extent of supersaturation.
According to the proportion of silica, the lava is distinguished as "acid" or "basic."
It will be easier for a while until we get to the Lava fields.
No evidences of recent lava flows can be found in the interior over the great alluvial plain, the Lower, or the Higher Steppes.
2 Port Lloyd, the chief anchorage (situated on Peel Island), is considered by Commodore Perry - who visited the islands in 1853 and strongly urged the establishment of a United States coaling station there - to have been formerly the crater of a volcano from which the surrounding hills were thrown up, the entrance to the harbour being a fissure through which lava used to pour into the sea.
Lava is much used for paving-stones in the neighborhood of volcanic districts, where pozzolana (for cement) and pumice stone are also important.
A vast variety of trinketsin coral, glass, lava, &c.is exported from Italy, or carried away by the annual host of tourists.