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Jarvis Island

Howland, Baker, and Jarvis islands are coral islands once celebrated for their guano deposits, which are worked by the American Guano Company of New York, and numerous vessels were annually chartered to load there. Several isolated islands in Oceania, some uninhabited, were under United States jurisdiction, including Howland, Baker, and Jarvis islands, Kingman Reef, and Palmyra and Johnston atolls. Devastation caused by World War II was obviously most extensive in areas within the combat zones. In a treaty of friendship signed in September 1979, the United States relinquished its claim to the eight Phoenix Islands and five central and southern Line Islands. The two northernmost Line Islands Kingman Reef and Palmyra Atoll as well as Jarvis, Baker, and Howland islands, which lay between the Gilbert and Line islands, remained United States territory, however.

Jarvis island was discovered by Capt. Brown, of the Eliza Frances, in 1821. It is nearly 2 miles long by 1 mile wide, trending east and west, and containing about 1000 acres. Like Baker and Howland islands, it has the general features of a coral island, but it differs from them essentially in the fact that it once contained a lagoon which has gradually been filled up with sand and detritus, while the whole island has undergone some elevation. It therefore presents a basin-like form, the surface being depressed from the outer edge towards the centre.

It is encircled by a fringing reef, or shore platform, about 300 feet wide; from this a gradually sloping beach recedes, the crown of which is from 18 to 28 feet high, forming a ridge or border of varying width, which surrounds the island like a wall, from the inshore edge of which the surface of the island is gently depressed. Within this depression there are other ridges parallel to the outer one, and old beach lines and water marks,the remaining traces of the waters of the lagoon, marking its gradual decrease and final disappearance.

This flat depressed surface in the center of the island is about 7 or 8 feet above the level of the sea. It bears but little vegetation, consisting of long, coarse grass, mesembryanthemum, and portulacca, and that is near the outer edges of the island where the surface is formed of coral sand mixed with more or less guano. In the central and lower parts the surface is composed of the sulphate of lime, and it is on this foundation that the principal deposit of guano rests.

This feature of Jarvis island is an important one to consider in studying the difference between the guano found on it and that on Baker island, for it readily explains the presence, in much of the Jarvis guano, of the great excess of sulphate of lime, remarked by all who have investigated it, while the unequal mechanical mixture of the guano with the underlying sulphate accounts for the lack of uniformity in different samples. In examining the foundation of the guano deposit on Baker or Howland islands, by sinking a shaft vertically, the hard conglomerate reef rock is found directly underlying the guano. Resting on this foundation the guano has undergone only such changes as the climate has produced.

On Jarvis island, however, after sinking through the guano, one first meets with a stratum of sulphate of lime (sometimes compact and crystalline, sometimes soft and amorphous) frequently two feet thick, beneath which are successive strata of coral sand and shells deposited one above the other in the gradual process by which the lagoon was filled up. Of the origin of this sulphate of lime there can hardly be any doubt. As the lagoon was nearly filled up, while (by the gradual elevation of the island) the communication between the outer ocean and the inner lake was constantly becoming less easy, large quantities of sea water must have been evaporated in the basin. By this means deposits would be formed containing common salt, gypsum, and other salts found in the waters of the ocean. From these the more soluble parts would gradually be washed out again by the occasional rains, leaving the less soluble sulphate of lime as found here.

Some additional light is thrown on this matter by the different parts of the surface, which, though nearly flat, shows some slight variety of level. The higher parts, particularly around the outer edges, are composed chiefly of coral sand, either mixed with or underlying guano. Nearer the centre is a large tract, rather more depressed, forming a shallow basin in which the bulk of the sea water must have been evaporated, and whose surface (now partly covered with guano) is a bed of sulphate of lime, while, further, there is a still lower point, the least elevated of the whole, where the lagoon waters were, without doubt, most recently concentrated.

This latter locality is a crescent shaped bed, about 600 feet long by 200 or 300 feet wide, having a surface very slightly depressed from the outer edge towards the middle. Around the borders are incrustations of crystallized gypsum and common salt, ripple marks and similar evidences of the gradually disappearing lake. The whole is composed of a crystalline deposit of sulphate of lime, which, around the borders, as already observed, is mixed with some common salt, while near the centre, where rain water sometimes collects after a heavy shower, the salt is almost entirely washed out, leaving the gypsum by itself. It is closely, but not hard, packed, and is still very wet.

Ships moor here, as at Baker island, to mooring buoys in very deep water. Capt. Wilkess in his Narrative of the United States Exploring Expedition, 1838-1842, speaking of Jarvis island, which was visited in December, 1840, by the surveying vessels Peacock and Flying Fish, said, It is a small coral island, triangular in shape, 13 miles in length east and west, and 1 mile wide north and south; it exhibits the appearance of a white sand beach, 10 or 12 feet above the sea, without a tree or shrub, and but a few patches of grass. The sea breaks violently around its shores, but no reef extends to any distance from the island, which may be closely approached. A few sea birds were seen about the island. No landing could be attempted, the surf being too heavy.

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Page last modified: 08-10-2017 18:29:21 ZULU