During the Tertiary period the great volcanoes of the Andes were formed, and there were smaller eruptions in the Sierras.
Several eruptions are recorded in Roman times.
High, while the Punta del Palo, the highest point of the brim of the crater of Vesuvius, varies materially with successive eruptions from 3856 to 4275 ft.
From 1845 to 1857 volcanic eruptions were very violent, and islands once fertile were devastated and nearly destroyed.
With the J urassic beds is associated an extensive series of eruptive rocks (gabbro, peridotite, serpentine, diorite, granite, &c.); they are chiefly of Jurassic age, but the eruptions may have continued into the Lower Cretaceous.
The date of these eruptions is still uncertain, but they probably continued to a very recent period.
In all these cases, however, the eruptions have now almost ceased; and the great volcanoes of the present day lie in the islands off the eastern and south-eastern coasts.
In most cases the eruptions appear to be of Pliocene or later date, but in the extreme north some of the basalt seems to belong to the Miocene period.
His chief publications were: Santorin et ses eruptions, 1879; (with A.
An effect of the greater tide-generating force will also be instability of the liquid magmas underlying volcanic areas, leading to violent eruptions and earthquakes.
The Eastern Andes is a magnificent range in the southern part of Peru, of Silurian formation, with talcose and clay slates, many quartz veins and eruptions of granitic rocks.
It is nowhere disturbed by volcanic eruptions, except at the very edge of the formation near Lake Titicaca, and in this respect it differs essentially from the Maritime Cordillera.
The height of the mountain varies from time to time within limits of several hundred feet, according to the effects of successive eruptions, but averages about 4000 ft.
Aso-take is still an active volcano, but its eruptions during recent years have been confined to ashes and dust.
Within the period of Japans written history several eruptions are recorded the last having been in 1707, when the whole summit burst into flame, rocks were shattered, ashes fell to a depth of several inches even in Yedo (TOkyO), 60 m.
Eruptions have been recorded since the earliest days of Japanese history.
Some are contained in alluvial depressions in the river valleys; others have been formed by volcanic eruptions, the ejecta damming the rivers until exits were found over cliffs or through gorges.
The igneous rocks occur at several geological horizons, but the great volcanic eruptions did not begin until the Tertiary period.
Between the two zones lies a row of Klippen, while towards the Hungarian plain the inner zone is bordered by a fringe of volcanic eruptions of Tertiary age.
The great similarity between the salts of the ocean and the gaseous products of volcanic eruptions at the present time, rich in chlorides and sulphates of all kinds, is a strong argument for the ocean having been salt from the beginning.
The Cainozoic volcanic history of New Zealand begins in the Oligocene, when the high volcanic domes of Dunedin and Banks Peninsula were built up. The Dunedin lavas including tephrites and kenytes correspond to the dacite eruptions in the volcanic history of Victoria.
The volcanic activity of the Taupo district lasted into the Pleistocene, and the last eruptions contributed many of its chief geographical features.'
Volcanic eruptions have been observed.
In other areas, however, there is still volcanic activity, and in many cases volcanoes to which only tradition attributes eruptions can hardly be classified as extinct.
The eruptions are said to have begun with the ejection of syenites, diorites and diabases, which probably took place at the close of the Cretaceous or the beginning of the Eocene period.
In the Miocene period andesites of various kinds were erupted, while at the close of the Pliocene began the great eruptions of basalt which reached their maximum in Quaternary times and continue to the present day.'
The earlier supposition that these vast lava flows came chiefly from fissure eruptions has been made doubtful by the later discovery of flat-sloping volcanic cones from which much lava seems to have been poured out in a very liquid state.
The region was by no means a peneplain before its slanting uplift; its surface then was hilly and in the south mountainous; in its central and still more in its northern part it was overspread with lavas which flowed westward along the broad open valleys from many vents in the eastern part: near the northern end of the range, eruptions have continued in the present cycle, forming many cones and young lava flows.
Eruptions are recorded for the years 1830, 1855 and 1858; and another eruption occurred in 1904.
The age of the several inhabited islands, or at least the time since the last eruptions on them, decreases from W.
1,55° 56° D world in 1823, the eruptions have consisted mainly in the quiet discharge of lava through a subterranean passage into the sea.
In the eruptions of 1823, 1832, 1840 and 1868 the floor of the crater rose on the eve of an eruption and then sank, sometimes hundreds of feet, with the discharge of lava; but since 1868 (in 1879, 1886, 1891, 1894 and 1907; and once, before 1868, in 1855) this action has been confined to Halemaumau and such other pits as at the time existed.
The first recorded eruption of Mauna Loa was in 1832; since then there have been eruptions in 1851, 1852, 1855, 1859, 1868, 1880-1881, 1887, 1896,1899 and 1907.
The eruptions of 1868, 1887 and 1907 were attended by earthquakes; in 1868 huge sea waves, 40 ft.
But the eruptions of Mauna Loa have consisted mainly in the quiet discharge of enormous flows of lava: in 1859 the lava-stream, which began to run on the 23rd of January, flowed N.W., reached the sea, 33 m.
Distant, eight days later, and continued to flow into it until the 25th of November; and the average length of the flows from seven other eruptions is nearly 14 m.
Tremendous forces have been at work, suggesting earthquakes and eruptions; but really all is due to the chemical and mechanical action of water.
The body was ultimately removed by the inhabitants of Naples to that city, where the relic became very famous for its miracles, especially in counteracting the more dangerous eruptions of Vesuvius.
After the destruction of one forest by volcanic eruptions another grew over it; it, too, was buried under volcanic material, and the process was repeated several times.
Similar eruptions, but on a much smaller scale, took place in other parts of Great Britain.
In China, at the close of the period, there were enormous eruptions of melaphyre, porphyrite and quartz-porphyry.
At the close of the Eocene period great eruptions of augite-andesite took place from two fissures which ran along the west coast.
No volcanic eruptions are known to have taken place in these mountains within the historic period, though Livy sometimes speaks of it " raining stones in the Alban hills " (i.
Thucydides mentions eruptions in the 8th and 5th centuries B.C., and others are mentioned by Livy in 125, 121 and 43 B.C. Catania was overwhelmed in 1169, and many other serious eruptions are recorded, notably in 1669, 1830, 1852, 1865, 1879, 1886, 1892, 1899 and March 1910.
The earliest eruptions of Etna are older than the Glacial period in Central and Northern Europe.
The presence of these fossils indicates that the eruptions were subaerial, and a comparison of them with those elsewhere found among Older Tertiary strata shows that they probably belong to the Oligocene stage of the Tertiary series of formations, and therefore that the basalt eruptions took place in early Tertiary time.
The eruptions were connected with innumerable fissures up which the basalt rose and from numerous points on which it flowed out at the surface.
That the volcanic period was a prolonged one is shown by the great denudation of the plateaus before the last eruptions took place.
Great damage was done by the eruptions of 1737 and 1794; the earthquake of 1857 and the eruption of the 8th of December 1861 were even more destructive.
The Imbabura volcano, celebrated for its destructive eruptions of mud and water, stands midway between the two ranges at the northern end of the plateau, and belongs to the transverse ridge of knot (nudo) which unites them.