Page:Popular Science Monthly Volume 20.djvu/373

Rh  between the surrounding strata, often to enormous distances. The hard crystalline materials and dikes remain now as mountains; the remnants of lava-streams stand as isolated plateaus; while the softer materials have been carried away. The matters ejected from volcanoes are often carried by winds or currents to very great distances. Pumice floats out upon the ocean, and has been found so thick near tin; Lipari Islands that a boat could hardly make progress through it, and so abundant near the Solomon Islands that it took ships three days to force their way through the floating masses. Volcanic dust has been blown all over the ocean and across it, and has been found by deep-sea soundings to cover the bottom of the deepest parts and those farthest from the land.

The results of volcanic action, whether viewed singly or collectively, appear immense, and seem to indicate that the earth is or has been the prey to tremendous and terrible forces. Yet the action passes, and probably always has passed, without inflicting any permanent disturbance upon the condition of the earth's surface over more than the most limited areas. Clear proofs exist that the volcanoes of the Hebrides, of the Auvergne, and of Hungary, were clothed in Miocene times with luxuriant forests. The Island of Java, near the heart of the present most active volcanic center on the globe, is at the same time one of the richest and most fertile spots in respect to vegetable and animal life. The slopes of Vesuvius afford the best field for vineyards, and are in constant demand for that purpose, notwithstanding the danger of spasmodic outbreaks, for the eruptions of the volcano are short and its periods of repose are long. Volcanic action is only one of the ordinary forces of nature, probably quite as beneficial as destructive in the long run.

 

THE vegetation on the southern slopes of the eastern Himalayas, three or four thousand feet above the sea, though by no means luxuriant, is said to be very agreeable and of much interest to the botanist. Among the plants native to these slopes, planted in the course of nature during the preparation of the earth for man, and left wild with the elephant and the leopard, is a shrub growing from twenty to thirty feet high, and well worthy to be selected for pleasant foliage and fine flowers. The lanceolate leaves are from two to six inches long, and the flowers are large and white, very fragrant, in clusters of two or three in the axils of the leaves. This is the tea-plant, of the genus Thea, very nearly allied to the genus Camellia, of which the 