Page:Africa by Élisée Reclus, Volume 3.djvu/131

 SAINT HELENA. 101 continued for unnumbered ages, must nevertheless have been an extremely slow process, owing to the intense hardness of these lava formations. After a many j-ears' careful study of the work of disintegration on the rock- bound coast, M. Melliss estimated at over 44,000 jears the time occupied in the destruction of certain headlands, of which nothing is now visible except a few reefs. All the St. Helena rocks — basalts, pozzolanas, pumice, vitrified or other materials — are of igneous origin. No other formations, sedimentary or crystalline, have been discovered, which might justify the theory sometimes put forward that the island was formerly connected with a continental mass. In some places, notably in Gregory's Valley, the basalt rocks are traversed by other and much harder basalts, ejected from below during some local underground disturbance. While the rest of the rock is eaten away to a great depth/ these dykes, which intersect each other in various directions, stand out like the walls of a vast edifice now in ruins. The delusion is heightened by the interstices of the columns, resembling those of masonry. The study of the relief of the land has shown that the centre of eruption lay on the south coast at the point now known as Sandy Bay. Here is still visible the crater, forming a regular semicircle washed by the surf from the high seas. But around this central nucleus is developed another semicircular crater, a magnifi- cent amphitheatre, w^hose main axis is indicated by the culminating peaks of the island. Some of the prominences on this outer circuit resemble gigantic pillars. Such are " Lot and his wife," which rise to the respective heights of 300 and 260 feet on the southern part of the volcanic enclosure. A huge detached boulder of clink-stone rests on end, like those " Stonehenges " which have become famous in the mythology of the European peoples. The higher crater has a diameter of no less than four miles, presenting in many places the aspect of chaos and gloom, as attested by such names as " Hell-Gate," and " Devil's Garden." Nevertheless, the finest cultivated tracts and most luxuriant orchards are found on the inner slopes of this crater. A winding carriage -road leads from the higher crests down to the bottom of the chasm. Weathered by time and deprived of its eruptive cones, the north side of St. Helena no longer presents the majestic appearance of other volcanic islands. Its aspect is rather that of a confused mass of black and reddish rocks encircled by jagged clifis and escarpments, but offering a somewhat monotonous profile above the gorges on the coast. Toward the east, however, a terminal headland stands out boldly, detached by a deep fissure from the main insular mass. Several eminences exceed 2,000 feet, the highest being the Peak of Diana (2,700 feet), which commands a panoramic view of the whole island, with its crests and valleys, its sharp peaks and deep ravines. At the time of its discovery, St. Helena was clad with dense forests down to the water's edge. But most of these have since disappeared, and five-sixths of the surface have been deprived of all vegetation. Hence nearly all the plants now occurring are exotics, introduced from Europe, Africa, America, and even Australia.