Eastern Melanesia is not a very clearly demarcated region geographically or politically. A distinction can be drawn, however, between the area included under this title and the myriad islands to the east, especially with reference to population and resources. The Lau Islands, easternmost of the Fijian Archipelago, comprise a transition area anthropologically between Melanesia and Polynesia. A great wealth of agricultural and mineral resources characterizes eastern Melanesia, an area that includes from west to east the Solomons, Santa Cruz Islands, New Hebrides, New Caledonia, Loyalty Islands, and Fiji.
The islands in this part of the southwest Pacific have various origins. Some are volcanic, built up from vents in the ocean floor; for example, Bagana on Bougainville in the Solomons is still active, and great eruptions have occurred on Ambrim, Tana, and Lopevi Islands in the New Hebrides. Others are coral atolls less than the height of a man above sea level. Several have complicated structures due to uplifts and the action of several earth-building agencies. Most of the islands are surrounded by coral reefs. The tops of the high mountainous islands are often obscured in clouds; they are all clothed with various kinds of forest; all abound in food for the native people, and are remarkable for grand and picturesque scenery. The atolls support little natural vegetation other than coconut, pandanus, and shrubs characteristic of the strandline.
Lying within the tropics, these bits of land have a uniformly warm temperature and generally heavy rainfall. The rainfall, however, varies considerably from one archipelago to another, and sometimes from one island to another in the same group. The southernmost islands, strongly affected by the trade winds, have rainy windward sides and drier lee coasts.