Note on Clipperton Atoll (Northern Pacific)

Abstract

In the eastern part of the Northern Pacific, in lat. 10° 17′ N., long. 109° 13′ W., and 600 miles away from the nearest point of the continent of North America, is a small, lonely atoll called Clipperton. It has never been properly surveyed, but was in 1840 sketched by Capt. Sir E. Belcher, R.N. Its lagoon, 2 miles in diameter, was then open to the sea in two places, both shallow. The remainder of the ring surrounding it was a few feet above water, forming two flat, bare, crescent-shaped islands. It was the haunt of innumerable sea-birds, as might be expected from its solitary position, and it is doubtless to these birds that the fact that no scrap of vegetation exists is due. Since the date of Sir E. Belcher's visit the entrances have been closed by piled-up coral-sand, the ring is complete, and the lagoon is cut off from the influx of ocean-waters, except by infiltration. So far, Clipperton Atoll only resembles many other islands of similar type and position, but there is one point which distinguishes it, so far as I know, from all other atolls, and that is the existence on one part of the ring of a mass of rock about 60 feet in height. Some atolls have an island somewhere near the centre of the lagoon, but none, as this, on the ring itself. 9 I have long wished to know the geological character of this rock, but it is only lately, by the