. Contributions to the geology and paleontology of the Canal Zone, Panama, and geologically related areas in Central America and the West Paleontology; Paleontology; Paleontology. Fig. 4. Copy of Darwin's figure illustrating conversion of a fringing into a barrier reef, according to his hypothesis. .4^—outer edge of the reef at the level of the sea. bb— Shores of the island. A'^'—Outer edge of the reef, after its upward growth during a PERIOD of subsidence. CC—THE LAGOON-CHANNEL BETWEEN THE REEF AND THE SHORES OF THE NOW ENCIRCLED LAND. B'B'—TUTL SHORES OF THE ENCIRCLED ISLAND. N. B.—
. Contributions to the geology and paleontology of the Canal Zone, Panama, and geologically related areas in Central America and the West Paleontology; Paleontology; Paleontology. Fig. 4. Copy of Darwin's figure illustrating conversion of a fringing into a barrier reef, according to his hypothesis. .4^—outer edge of the reef at the level of the sea. bb— Shores of the island. A'^'—Outer edge of the reef, after its upward growth during a PERIOD of subsidence. CC—THE LAGOON-CHANNEL BETWEEN THE REEF AND THE SHORES OF THE NOW ENCIRCLED LAND. B'B'—TUTL SHORES OF THE ENCIRCLED ISLAND. N. B.—IN THIS, AND THE FOLLOWING CUT, THE SUBSIDENCE OF THE LAND COULD ONLY BE REPRESENTED BY AN APPARENT RISE IN THE LEVEL OF THE SEA. subsidence and the conversion of a frhighig into a barrier reef. It also attempts to account for extensive submarine platforms by assuming that they have been built upon sloping basements through agencies depeiident on the presence of reefs. (See text-figs. 4, 5, 6.) Dana's interpretation ' is essentially that of Darwin. a" ^ i^__c' , a". FiQ. 5. Copy of Darwin's figure illustrating conversion of a barrier reef into an atoll, ac. CORDING to his HYPOTHESIS. ^'^'—OUTER EDGES OF THE BARRIER-REEF AT THE LEVEL OF THE SEA. The COCOA-NUT trees represent CORAL-ISLETS FORMED ON THE REEF. CC—THE LAGOON-CHANNEL. £'£'—The shores of the island, generally formed of low alluvlal land and of coral detri- tus FROM the lagoon CHANNEL. A"A"^THE OUTER EDGES OF THE REEF, NOW FORMING AN ATOLL. C—The LAGOON of the newly formed ATOLL. According to the scale the depth of the lagoon AND OF THE LAGOON CHANNEL IS EXAGGERATED. That Darwin considered an alternative hypothesis is shown by the following quotation: I may here observe that a bank either of rock or of hardened sediment, level with the surface of the sea and fringed with living coral, would be immediately converted into an atoll, without passing, as in the case of a reef fringi
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Keywords: ., bookcentury1900, bookdecade1910, bookpub, booksubjectpaleontology
