Document ID: chunk:federal_register_of_legislation:F2015L01389:body:0:p54
Version: federal_register_of_legislation:F2015L01389
Segment Type: other
Provision Reference: 
Character Range: 156735–159512

series of parallel rubble ridges, that are dipped and stratified like beachrock.
The Cocos (Keeling) Islands were the only coral atolls that Charles Darwin visited in 1836 as he developed his well-known theory of coral atoll formation (Darwin 1842), in which he asserted that the upgrowth of coral reefs continued long after the seamounts that supported them had subsided. While others, including Guppy (1889) and Wood-Jones (1912), presented alternative theories, Darwin's subsidence theory of coral reef development gained wide acceptance.
The location of the now closed entrance to the lagoon is unusual because it developed on the most windward side of the island, rather than in the shelter of the leeward side. Indeed, the island is the inverse of the horseshoe shape that Guppy (1889) considered the typical style of development of the main atoll. This has led a number of observers, starting with Fitzroy (1839), to suggest that the island developed from a series of formerly unconnected islands.
Some indication of the age of the island has been found through radiocarbon dating. A coral from a conglomerate on the northeast of the island dated 3,840 ± 85 years before present (BP). Similarly, a coral shingle sampled from a pit in the centre of the island was dated as 3,060 ± 60 years BP, suggesting little time difference between the formation of the beach at the margin of the reef platform and the formation of the island itself. Continual additions to the island have occurred over the past 3,000 years, including the build-up of sediments and coral blocks during cyclonic events (Woodroffe et al. 1994).
Soils
The soils of North Keeling Island are calcareous and derived from coral breakdown. They comprise a relatively thin layer of sandy loam, which in places grades into moderately and/or very stony sand comprising considerable amounts of coral clinker. They overlay a highly permeable sub-stratum which allows rapid leaching of nutrients. On the main (southern) atoll, long-term leaching has led to deficiencies in iron, potassium, copper, manganese, magnesium and other minerals (Cameron McNamara Consultants 1984). This leaching has probably also occurred on North Keeling Island. Similarly, the soils of North Keeling Island are expected to be highly alkaline, as on the southern atoll, with pH levels of between 8.0 and 8.5. Soils abutting the outer shore are subject to wave erosion during high tides and storm surges.
The lagoon shore of the island slopes gradually and deepens slowly. Its maximum depth is less than 2 metres. The bottom, and much of the beach, is a fine, greyish sandy silt, much of which is derived from decaying vegetation. Towards the eastern recesses this is greyer and darker, and in the north-east corner the beach is composed