Strata of volcanic rock subjacent to the city and its environs, and constructed originally for the interment of the Christian dead.
It attracts many visitors both as a health resort and on account of the magnificent scenery and remarkable volcanic phenomena of the surrounding district.
Mt Taylor in western New Mexico is of similar age, but here dissection seems to have advanced farther, probably because of the weaker nature of the underlying rocks, with the result of removing the smaller cones and exposing many lava conduits or pipes in the form of volcanic necks or buttes.
In the volcanic districts of the south-west of Scotland and the north-east of Ireland plant-beds are found intercalated between the lava-flows.
In 1825 another volcanic eruption took place accompanied by earthquakes, and two hills were thrown up. The port of Naos on the south-east of the island affords safe anchorage.
Equally indecisive is the further exploration as to evidence for the opinion held by other naturalists that the endemic species of the different islands have resulted from subsidences, through volcanic action, which have reduced one large island mass into a number of islets, wherein the separated species became differentiated during their isolation.
Goldfield and the Taupo volcanic district.
The materials are quartz crystal, basalt, porphyry, syenite, granite, volcanic ash, various metamorphics, serpentine, slate, dolomite marble, alabaster, many colored marbles, saccharine marble, grey and white limestones.
The direction of the great volcanic cones, which rise in an irregular line above it, is not identical with the main axis of the Sierra itself, except near the Mexican frontier, but has a more southerly trend, especially towards Salvador; here the base of many of the igneous peaks rests among the southern foothills of the range.
The hills of the north-east are mainly the crests of lavaplateaux, which carry the mind towards Skye and the volcanic province of the Faeroe Islands.