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Geological Observations on the Volcanic Islands, visited during the Voyage of H.M.S. Beagle is a book written by the English naturalist Charles Darwin. The book was published in 1844, and is based on his travels during the second voyage of HMS Beagle, commanded by captain Robert FitzRoy.
- Charles Darwin, John W. Judd
- 1844
Geological Observations on the Volcanic Islands, Visited During the Voyage of HMS Beagle Published online: 05 August 2011 Print publication: 02 June 2011, pp 23-33 First published in: 1844; Chapter; Get access
- Basaltic Rocks.
- Volcanic Bombs.
- Aeriform Explosions.
- Ejected Granitic Fragments.
- Trachytic Series of Rocks.
- Veins in The Earthy Trachytic masses.
- Siliceous Sinter and Jasper.
- Concretions in Pumiceous Tuff.
- Formation of Calcareous Rocks on The Sea-Coast.
- A Frondescent Calcareous incrustation.
The overlying basaltic lava is in some parts extremely vesicular, in otherslittle so; it is of a black colour, but sometimes contains crystals of glassyfeldspar, and seldom much olivine. These streams appear to have possessedsingularly little fluidity; their side walls and lower ends being very steep,and even as much as between twenty and thirty fe...
(FIGURE 3: FRAGMENT OF A SPHERICAL VOLCANIC BOMB, with the interior partscoarsely cellular, coated by a concentric layer of compact lava, and this againby a crust of finely cellular rock. FIGURE 4: VOLCANIC BOMB OF OBSIDIAN FROM AUSTRALIA. The upper figure gives afront view; the lower a side view of the same object.) These occur in great numbers st...
The flanks of Green Mountain and the surrounding country are covered by a greatmass, some hundred feet in thickness, of loose fragments. The lower bedsgenerally consist of fine-grained, slightly consolidated tuffs (Some of thispeperino, or tuff, is sufficiently hard not to be broken by the greatest forceof the fingers.), and the upper beds of great...
In the neighbourhood of Green Mountain, fragments of extraneous rock are notunfrequently found embedded in the midst of masses of scoriae. LieutenantEvans, to whose kindness I am indebted for much information, gave me severalspecimens, and I found others myself. They nearly all have a graniticstructure, are brittle, harsh to the touch, and apparent...
Those occupy the more elevated and central, and likewise the south-eastern,parts of the island. The trachyte is generally of a pale brown colour, stainedwith small darker patches; it contains broken and bent crystals of glassyfeldspar, grains of specular iron, and black microscopical points, whichlatter, from being easily fused, and then becoming m...
These veins are extraordinarily numerous, intersecting in the most complicatedmanner both coloured varieties of the earthy trachyte: they are best seen onthe flanks of the “Crater of the old volcano.” They containcrystals of glassy feldspar, black microscopical specks and little dark stains,precisely as in the surrounding rock; but the basis is ver...
The siliceous sinter is either quite white, of little specific gravity, andwith a somewhat pearly fracture, passing into pinkish pearl quartz; or it isyellowish white, with a harsh fracture, and it then contains an earthy powderin small cavities. Both varieties occur, either in large irregular masses inthe altered trachyte, or in seams included in ...
The hill, marked in Map 2 “Crater of an old volcano,” has no claimsto this appellation, which I could discover, except in being surmounted by acircular, very shallow, saucer-like summit, nearly half a mile in diameter.This hollow has been nearly filled up with many successive sheets of ashes andscoriae, of different colours, and slightly consolidat...
On several of the sea-beaches, there are immense accumulations of small,well-rounded particles of shells and corals, of white, yellowish, and pinkcolours, interspersed with a few volcanic particles. At the depth of a fewfeet, these are found cemented together into stone, of which the softervarieties are used for building; there are other varieties,...
(FIGURE 5. AN INCRUSTATION OF CALCAREOUS AND ANIMAL MATTER, coating thetidal-rocks at Ascension.) In many respects this is a singular deposit; it coats throughout the year thetidal volcanic rocks, that project from the beaches composed of broken shells.Its general appearance is well represented in Figure 5; but the fronds ordiscs, of which it is co...
geology of the voyage of the beagle; being. the structure and distribution. of. coral reefs. [a plan of the island of ascension.] geological observations. on the. volcanic islands, visited during the voyage of h. m. s. beagle, together with. some brief notices on the geology of australia and the cape of good hope. being the second part of
Charles Darwin (1809–1882) published Observations on the Volcanic Islands in 1844. It is one of three major geological works resulting from the voyage of the Beagle, and contains detailed geological descriptions of locations visited by Darwin including the Cape Verde archipelago, Mauritius, Ascension Island, St Helena, the Galápagos, and ...
- Charles Darwin
- 2011
18. Okt. 2008 · Geological Observations on the Volcanic Islands, Visited During the Voyage of H.M.S. Beagle ... Book digitized by Google from the library of the New York Public Library and uploaded to the Internet Archive by user tpb.
Nature - Geological Observations on the Volcanic Islands and Parts of South America visited during the Voyage of HMS “Beagle”
