The Solomon Islands; Their Geology, General Features, and Suitability for Colonization

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1887. Not illustrated. Excerpt: ... CHAPTER V. THE RECENT CALCAREOUS FORMATIONS OF THE SOLOMON ISLANDS. C1INCE my observations on the calcareous formations of this group have an important bearing on the explanations which have been held of the origin of coral reefs, I will very briefly allude to this subject. Nearly half a century ago, Mr. Darwin1 advanced the theory of subsidence, by which, through the sinking of the seabottom, the fringing-reef was transformed into a barrier-reef and the barrier-reef into an atoll. This view was soon generally accepted and came to be regarded, to employ the words of Dr. A. Geikie, as comprising one of the most impressive generalisations with which geology, fertile in such achievements, had yet astonished the world. This theory received the active support of Professor Dana,3 after the examination of many Pacific reefs. Investigators in other regions, however, failed to find in this view an explanation of the facts that came under their observation. Professor Louis Aerassiz in the case of the Florida reefs, Professor Joseph LeConte in that of the same region,4 Professor Semper in the instance of the Pelew Islands, and Dr. Rein in the case of the Bermudas, brought forward facts opposed to the theory of subsidence. At length, in 1880, Dr. John Murray 6 advanced the view, based on his observations during the Challenger Expedition, that atolls and barrier-reefs owe their form to their more rapid growth at the margins on account of the more abundant food-supply, and to the removal of the dead coral from the interior by the carbonic acid in the sea-water. Atolls, according to his views, are based, either on the submerged stump of a volcanic island which has been reduced by the waves to the lower limit of breaker-action, or on the summit of a sub-marine mountain, Co...