Several eruptions are recorded in Roman times.
Volcanic eruptions have been observed.
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 France, as in Great Britain, volcanic eruptions occurred during several of the Palaeozoic periods, but during the Mesozoic era the // /
The first eruptions piled up huge domes of lavas rich in soda, including the geburite-dacites and sOlvsbergites of Mount Macedon in Victoria, and the kenyte and tephrite domes of Dunedin, in New Zealand.
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.
There is historic evidence of mud eruptions in some of the volcanic areas.
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.'
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.
In Luzon trachytic tuffs are sometimes interstratified with nummulitic limestone, thus showing that the eruptions had already begun in the Eocene period.
Only a few eruptions have been recorded of any of these, however, except Taal and Mayon, and there has been no great eruption of Taal since 1754.
But there were 26 eruptions of Mayon in the 19th century, and those of 1814 and 1897 were of great violence.
The end of the Cretaceous period saw the beginning of a series of great earth movements ushered in by volcanic eruptions on a scale such as the earth has never since witnessed, which resulted in the upheaval of the Himalayas by a process of crushing and folding of the sedimentary rocks till marine fossils were forced to an altitude of 20,000 ft.
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.
The name is derived from imba, fish, and bura, mother, and is said to have originated from the quantities of a fish called " prenadilla " (Pimelodus cyclopum) discharged from its crater during one of its eruptions - a phenomenon which, after a searching investigation, was discredited by Wagner.
There is a tradition that this mountain was once higher than Chimborazo, but a series of eruptions caused the cone to fall in and reduced its summit to its present altitude and broken appearance.
Its eruptions are not on a grand scale, but small outbursts of lava and explosions of steam occur at frequent intervals, and at longer intervals more violent explosions in which the molten rock is thrown 2000 ft.
Perhaps no Ecuadorean volcano is better known than Pichincha, the " boiling mountain," because of its destructive eruptions and its proximity to the city of Quito.
There have been five eruptions of Pichincha since the Spanish conquest - in 1539, 1566, 1575, 1587 and 1660.
Its fame rests on Humboldt's publication of the tradition that great numbers of this tiny fish had been thrown out during the eruptions of Imbabura and other volcanoes.