Page:Popular Science Monthly Volume 86.djvu/527

Rh in the Society and Marquesas Islands. The little island of Kobu near Nairai is a mass of volcanic rock, 90 feet in height, and is so strongly magnetic that a compass placed upon its summit is deflected 85°.

In the Fijis the erosion has gone so far that most of the old volcanic rims have disappeared. Totoya and Thombia are, however, beautiful cup-like craters, their centers now being harbors encircled by crescent shaped ridges, and there are a few fairly M-ell-defined craters among the mountains of the larger islands. Indeed, at Kambara a small volcano has in recent, but still prehistoric, times broken through the elevated coral reef, but no native myths speak of volcanic eruptions.

The Fijis are much older than the large islands of the Hawaiian group or than some of the Samoan and Tongan islands, the volcanoes of which are still active. Indeed, in the interior of Viti Levu plutonic rocks and slates are found attesting to the considerable age of this island, allying it to such land masses as New Zealand or New Caledonia, which are partly volcanic and partly continental in character. Thus the Fijis differ from the simple volcanic tumuli which constitute the Hawaiian, Samoan, Society and Marquesas islands. In Hawaii and Tahiti we find great central volcanic peaks, from the summits of which deep valleys radiate outward to the sea, but in Fiji the large islands have been formed by fusions between many adjacent volcanic cones, and in later times the erosion has gone so far and local elevations and depressions have been so frequent that the landscape is broken and wholly irregular.

Indeed, the islands have not been passive during all the ages in which the rains have worn them down, for there have been depressions, and also great upheavals here and there, as at Yanua Mbalavu, where the old coral reef is now a bold precipice of overhanging castellated craffs towering far above the waves that dash at its feet. This old coral rock is cavernated and, at least one place along the shore, at Black Swan Point, on Yanua Mblavu Island, one may enter through a small cleft in the precipice and find oneself in a spacious chamber several hundred feet in height, with veil-like sheets of stalactites sparkling in the dim light that wanders inward through some hidden rift far up in the vaulted roof. A deep pool of wonderfully clear ocean water lies within this shadowy retreat, and brilliant blue and green fish flit butterfly-like through their natural aquarium, the floor of which is carpeted by graceful sea-whips, and slowly creeping crinoids with long feathery arms.

Many other islands also exhibit elevated coral reefs, which in some cases, as at Vatu Vara, have been lifted nearly 1,000 feet above the sea, and, near Suva, the hillside is full of fossil sea-shells and corals. We can see that the islands were once much larger than they are to-day, for nearly every one is encircled by a coral reef several miles out to sea, which marks the contour of the old coast line. Indeed, at Astrolabe