WORD OF THE DAY
Its fires are not volcanic, but result from the combustion of coal some distance underground, giving off much smoke and steam; geologists estimate that the burning has been going on for at least 800 years.
In connection with the volcanic districts we may mention Le Mofete, the pools of Ampsanctus, in a wooded valley S.E.
Lava is much used for paving-stones in the neighborhood of volcanic districts, where pozzolana (for cement) and pumice stone are also important.
But it is notable that all recent volcanic action was confined to a wide belt parallel to the coast.
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.
Of these Ischia and Procida, close to the northern headland of the Bay of Naples, are of volcanic origin, as is the case also with the more distant group of the Ponza Islands.
North of the fiftieth parallel the depths diminish towards the north-east, two long submarine ridges of volcanic origin extend north-eastwards to the southwest of Iceland and to the Faeroe Islands, and these, with their intervening valleys, end in a transverse ridge connecting Greenland, through Iceland and the Faeroe Islands, with Northwestern Scotland and the continental mass of Europe.
The Tertiary deposits cover the whole of the central depression, where they are associated with extensive flows of lava and beds of volcanic ash.
Contemporaneous volcanic rocks are associated with the Ordovician beds and with the Rhaetic sandstones in several places.
Professor Suess, to whom the above description is due, finds that the Mediterranean forms no exception to the rule in affording no evidence of elevation or depression within historic times; but it is noteworthy that its present basin is remarkable in Europe for its volcanic and seismic activity.
The Aeolian or Lipari Islands, a remarkable volcanic group, belong rather to Sicily than to Italy, though Stromboli, the most easterly of them, is about equidistant from Sicily and from the mainland.
Lava streams and other signs of volcanic action abound, but there has been no igneous activity since the Spaniards took possession.
The Hauraki Gulf, a great square inlet opening northward, is studded with islands of considerable elevation; Rangitoto, which protects the harbour, is a volcanic cone reaching nearly l000 ft.
by the undulating volcanic plain of the Roman Campagna, from which the mountains rise in a wall-like barrier, of which the highest point, the Monte Gennaro, attains 4165 ft.
deep, is almost circular, and was the central point of a large volcanic district, though it is probably not itself an extinct crater.
The hot spring which still survive from the period of volcanic activity, rise at a temperature of 147° Fahr.