Ebook The Geology of the Isles of Scilly

The material formed by the denudation of the granite is an im portant component of some of the islands. This granite waste takes two forms, angular Head, and Blown Sand. The latter IS by far the more important so far as bulk is concerned, and has often played the curious role of uniting separate granite masses to form one island or continuous land-surface indeed, this phenomenon is one of the features of the Scilly Isles. The climate of the Scilly Isles is essentially mild, being cooler in summer and warmer in winter than that of the adjacent mainland even sub-tropical plants grow Well in sheltered places, not so much from the warmth of the climate as from the absence of cold in winter. The finest examples of these exotic plants are seen in the gardens of Tresco Abbey. The rainfall is only some 32 inches, much less than on the main land of Cornwall but a considerable amount of moisture is slowly deposited on the land at certain seasons owing to sea-fogs produced by the action of cold air-currents passing over the warm surface of the Gulf-stream.