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Marie Galante Two simple examples of second-cycle islands may be adduced. The first is Marie Galante, a limestone island in the Guadeloupe group, nine miles in diameter, with a remarkably even profile at a height of 670 feet. As represented on H. O. Chart 363, the relief seems stronger than it would be inferred to be from the view of the island reproduced from a recent photograph by Mr. G. S. Miller, Jr., of Washington. This island was seen only in the distance: no detailed studies have been made of it. It appears to be an upraised atoll, somewhat benched during and moderately dissected since its recent emergence, not yet provided with a bank of second generation. Sombrero The second example I did not see at all; it is Sombrero, southeast of the Virgin group, a narrow limestone island a mile long and from 25 to 40 feet high. Its shore cliffs plunge to depths of 8 to 14 fathoms, and it is surrounded by a bank three by four miles across and 30 or 40 fathoms deep at the outer edge. Julien spent several months on the island nearly half a century ago, 14 and gave an excellent account of it as an uplifted atoll, originally about as large as the bank of second generation that now surrounds it, but reduced to its present size by wave attack. He concluded that its "marine deposits appear to have been formed upon the area, oscillating vertically, of the bottom of a lagoon, more or less inclosed," as if it had the basin form peculiar to atolls. The rarity of atolls in the West Indies is recognized, but it is held that Sombrero must have been one, because of the repeated occurrence of lagoon-like limestones upon it; and it is added that "many of the isolated keys and banks with which its [the West Indian] archipelagoes abound, may reveal to future examination the possession (in their former history if not at present) of a true atoll construction." The parenthetical remark here included is, in my opinion, fully justified by the features of Antigua, to be described below. Six beds of limestone were recognized on Sombrero, bearing many fossils like the forms now living on the bank around the abraded island, and indicating as many subsidences with deposition followed by emergences with erosion. The following extracts from Julien's account illustrate the detailed analysis of the island's history that he felt warranted in making. At an early stage in its growth "the whole subsiding area was covered with a close and uninterrupted madrepore reef. From the few species and individuals of the shells in the coral-bed, from their fragility and that of the corals, and from the absence of fragments, it may be inferred that the reef grew in comparatively quiet water. . . . The quietness of the locality could not have been due simply to great depth. We are forced to believe . . . that some barrier encircled the reef . . . varying at different periods in height relative to the bottom of the lagoon. Indeed such a barrier must necessarily have been formed on the outer edge of the oscillating area, on the first occasion that the superincumbent sea was sufficiently shallow to support coral life, creating an atoll when it reached the sea level. . . . Coral life ceased over the central area, with the exception of many scattered clumps and the frequent superposition of a more delicate species. These remnants were next overlaid with coarse sand from the shore of the lagoon and the barrier islets, and thereby killed. The greater quietness and depth of the water favored the abundant growth of a few species of fragile shells, whose unbroken condition proves that they grew where they now lie." Similar inferences are presented regarding the several overlying limestone beds. The formation of the sixth bed was followed by two oscillations of level without submergence; the guano deposits which then accumulated in crevices in the limestone have been quarried and shipped away. "Thus then this little rocky islet stands out in the open ocean, a solitary pillar, like those of the Temple of Serapis, marking old convulsive throbs and prolonged oscillations of the deep-sea bottom." Sombrero must have had, according to the scheme of development proposed in the present essay, a somewhat more extended experience than the small rimless banks which represent the ultimate stage of one-cycle islands; for after passing through the firstcycle stages represented by Saba, the Saints, Redonda, and an atoll, it appears to have been introduced into a second cycle by a moderate uplift and then to have passed through the young second-cycle stage of Marie Galante, preparatory to reaching its own mature stage of advanced abrasion. Its emergence would therefore seem to have been early enough for it to have suffered low-level abrasion in at least one Glacial epoch, while the emergence of Marie Galante appears to have been so recent that it hardly bears the marks of even the latest Glacial epoch of low-level abrasion. This interpretation is necessarily in large measure hypothetical, for most of the conditions and processes it involves are lost in the past. Nevertheless, in so far as the interpretation is correct, the past conditions and processes involved in the interpretation were facts in their own time just as truly as are the observable conditions and processes of today. That the hypothetical interpretation may be accepted as essentially correct appears from the simple manner in which it assembles and correlates a variety of insular features which at first sight seem to have little in common. Home