United States or Cocos Islands ? Vote for the TOP Country of the Week !
The study of volcanoes may be divided into two distinct branches; one, simply mineralogical, is directed to the examination of the stony strata, altered or produced by the action of fire; from the formation of the trachytes or trap-porphyries, of basalts, phonolites, and dolerites, to the most recent lavas: the other branch, less accessible and more neglected, comprehends the physical relations which link volcanoes together, the influence of one volcanic system on another, the connection existing between the action of burning mountains and the commotions which agitate the earth at great distances, and during long intervals, in the same direction.
The geologists were interested, and we others learnt something of olivines, green in crystal form or oxidized to bright red, granites or granulites or quartzites, hornblende and feldspars, ferrous and ferric oxides of lava acid, basic, plutonic, igneous, eruptive schists, basalts &c. All such things I must get clearer in my mind. Tuesday afternoon a cold S.E. wind commenced and blew all night.
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. By James Nasmyth.
In the valley of Tia-auru, the commonest rocks are basalts with much olivine, and in some cases almost composed of large crystals of augite. I picked up some specimens, with much glassy feldspar, approaching in character to trachyte.
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.
Diorite forms the great mass of this stratum; it is of a dark green colour, granular, with small grains, and destitute of quartz; its mass is formed of small crystals of felspar intermixed with crystals of amphibole. This rock of diorite is covered at its surface, by the effect of decomposition, with a yellowish crust, like that of basalts and dolerites.
Vincent, St. Lucia, and St. In order to exhibit in one point of view the whole system of the volcanoes of the smaller West India Islands, I will here trace the direction of the islands from south to north. Grenada, an ancient crater, filled with water; boiling springs; basalts between St. George and Goave. St. Vincent, a burning volcano. St.
His place was no longer in the cart, but at the head of the troop. The next day, the 19th of February, the colonists, leaving the shore, where, beyond the mouth, basalts of every shape were so picturesquely piled up, ascended the river by its left bank. The road had been already partly cleared in their former excursions made from the corral to the west coast.
Marble unlike sandstones, clay-slates, and basalts, which are kindred to the earth and the elements, and find themselves at home in any situation, all things making friends with them, mosses, lichens, ivies is a dead, cold material, and does not harmonise with surrounding circumstances.
Recent eruptive rocks, mainly basalts, form a line of hills almost bare of vegetation between Benguella and Mossamedes. Nepheline basalts and liparites occur at Dombe Grande. The presence of gum copal in considerable quantities in the superficial rocks is characteristic of certain regions. Climate. With the exception of the district of Mossamedes, the coast plains are unsuited to Europeans.
Word Of The Day