grasses, spores of algae, and the eggs of molluscs and other invertebrates may stick to the feet or feathers of birds, particularly migratory or aquatic birds, and in this way may travel long distances. The main island, Grande Terre hosts multiple habitats under the influence of varied precipitation, geology, edaphic factors and altitude. New Caledonia has several biotopes, including dense evergreen forests, maquis shrubland, sclerophyllous forest (dry forest), wetlands, savannas, and halophytic vegetation. The island has two main ecoregions: the greater area is occupied by the eastern New Caledonia rainforest while the now-fragmentary New Caledonia dry forest runs along the west coast. The most conspicuous aspects of the New Caledonian marine environment are associated with the surrounding coral reef. Such circumstances may be expected in general to promote biodiversity, but in the case of New Caledonia, a striking feature is the intense biodiversity in such a small land area. Presumably this is partly due to the edaphic and topographic features that define a number of discrete regions and ecological gradients. However, the local species do not always occupy all the potential niches, leaving the territory vulnerable to certain forms of invasion. The larger flora include Nothofagus, Beilschmiedia, Adenodaphne, Winteraceae, Myrtaceae, southern sassafras (Atherospermataceae), conifers of Araucariaceae, Podocarpaceae, and Cupressaceae, and tree ferns. Geologic origins New Caledonia comprises fragments of the continental crust of Gondwana, dating to over one hundred million years ago (MYA), as well as volcanic material. The fragments apparently split from the Indo-Australian tectonic plate. Prevailing opinion holds that the archipelago represents the non-submerged regions of the continental fragment known as Zealandia. Zealandia broke away from the Australian part of Gondwana some 80-90 MYA. The separation of New Caledonia from mainland contact must have begun some tens of millions of years ago, probably during the Cretaceous period. However, the view of the island as a surviving fragment of the Cretaceous period is obsolete. Islands from that time are partly or fully submerged. Most modern New Caledonian terranes formed via accretion of oceanic island arcs and seamounts. The biota evolved as metapopulations on islands that changed constantly until they merged into the archipelago. This hypothesis that the islands and their biota emerged some 30 MYA during the Oligocene better explains the organisms that occur in New Caledonian biota. In the Carboniferous and Permian, New Zealand and New Caledonia were on the periphery of Gondwana, which included Africa, South America,