The physiography of the Low Isles has been systematically compared after a span of 17 years, 1928-1945, with the assistance of ground observations and air photographs of both dates. This unique comparative study of a coral island led to these conclusions: (1) The shape of the reef platform maintains itself in the "horse''s hoof" pattern with its apex to the Trade Wind direction, southeast, as noted by others. Total growth in 17 years was unnoticeably slow. (2) The superficial veneer of rampart material is also controlled by Trade Wind influence but is considerably modified by periodic northeasterly storms of cyclonic force. This results in an asymmetrical development of multiple ramparts on the eastern side of the reef platform, thus providing shelter for the considerable growth of mangrove which contributes further to the lack of balance in the otherwise symmetrical pattern of the "horse''s hoof." (3) The authors believe that rampart development proceeds by accretion and continues with the gradual ageing of the reef. A succession of ramparts, 1, 2, 3, and 4 was recognized; the last has been formed since 1928. (4) The authors do not regard any tectonic or eustatic variation in the relative sea-level as necessary to explain the growth of ramparts. (5) The origin of high shingle-tongues, a feature of similar island reefs which are partly awash, not only in the north Queensland area but in the East Indies and elsewhere, is explained by the effect of a dominant wind direction on wave patterns "shepherding" the shingle debris in converging lines. (6) The importance of acid action in the Mangrove Swamp and Park areas of the island in enabling the mangroves to become established appears to be greater than previously recognized. (7) The Sand Cay in the northwest fringe of the island appears to be basically a large sand bank accumulated on the leeward side of the reef platform, maintained here primarily by a nicely balanced equilibrium of forces of wind and wave, and only secondarily by the development of beach rock which acts as a natural bulwark.