Volcanic Islands

Although in some respects more technical in their subjects and style than Darwin’s “Journal,” the books here reprinted will never lose their value and interest for the originali...

Rocks of the lowest series. A calcareous sedimentary deposit, with recent shells, altered by the contact of superincumbent lava, its horizontality and extent. Subsequent volcani...

During our short visit at this and the four following islands, I observed very little worthy of description. Fernando Noronha is situated in the Atlantic Ocean, in latitude 3 de...

Basaltic lavas. Numerous craters truncated on the same side. Singular structure of volcanic bombs. Aeriform explosions. Ejected granitic fragments. Trachytic rocks. Singular vei...

due to the separation from the surrounding mass of the whole or part of some mineral substance, and its aggregation round certain points of attraction. Guided by this fact, I ha...

Lavas of the feldspathic, basaltic, and submarine series. Section of Flagstaff Hill and of the Barn. Dikes. Turk’s Cap and Prosperous Bays. Basaltic ring. Central crateriform ri...

apparently it is not of very common occurrence. Sir G. Mackenzie, however, states (page 372 “Travels in Iceland”) that all the veins in Iceland have a “black vitreous coating on...

Chatham Island. Craters composed of a peculiar kind of tuff. Small basaltic craters, with hollows at their bases. Albemarle Island; fluid lavas, their composition. Craters of tu...

The sinking of crystals in fluid lava. Specific gravity of the constituent parts of trachyte and of basalt, and their consequent separation. Obsidian. Apparent non-separation of...

for oxygen than iron has, rise from the interior of the mass to the surface. But a similar cause can hardly apply to the separation of the crystals of these lava-streams. The co...

New South Wales. Sandstone formation. Embedded pseudo-fragments of shale. Stratification. Current-cleavage. Great valleys. Van Diemen’s Land. Palaeozoic formation. Newer formati...

The first impression, from seeing the correspondence of the horizontal strata, on each side of these valleys and great amphitheatre-like depressions, is that they have been in c...

of oysters and clams having been destroyed by the gradual filling up of the shallow lagoons and channels, on the shores of the southern United States. At Chiloe, in South Americ...