The Solomon Islands lie to the east of New Guinea and to the north of the New Hebrides. The main group comprises a double chain of islands, stretching roughly from north-west to south-east. It includes seven major islands: Bougainville, Choiseul, Ysabel, New Georgia, Malaita, Guadalcanal, and San Cristobal; between 20 and 30 smaller islands, and numerous islets. Many islands in this archipelago are very mountainous, but Rennell Island, a raised atoll, is nearly flat.
Several smaller groups of islands, also isolated, are usually considered as part of the Solomons Archipelago. They include: to the south, the large island of Rennell and its smaller neighbor, Bellona; to the southeast, the Santa Cruz group of Ndeni, Vanikoro, and Utupua; the Reef and Taumako groups, and the small isolated islands of Tikopia, Anuta, and Fatutaka; and, to the east and north, a number of atolls of which the most important are Ontong, Java, and Sikaiana. The area of the Protectorate is 12,400 square miles and of the Solomon Islands in the trusteeship 4100 square miles.
The Solomons, predominantly of volcanic origin, are a link in the larger chain of volcanic ranges and islands stretching from southeast Asia through Sumatra, Java, and New Guinea and continuing beyond the Solomons into the New Hebrides. The cores of the main islands are ancient lavas, many of which are overlain by recent deposits, both volcanic and sedimentary. Active volcanoes exist at each end of the group, on Mts. Balbi and Bagana, in Bougainville, and in Tinakula in the Santa Cruz group.
The economic resources of the Solomons, only slightly exploited, are imperfectly known. The islands first became of economic importance as a source of labor for the sugar-cane plantations of Queensland and Fiji. As a field for tropical agriculture, they did not attract attention until the beginning of the twentieth century, when individual settlers and large firms began to take up land for coconut plantations. To avoid too great dependence on a single crop, subsidiary crops were tried, but the quantities grown were small.
The igneous rocks of the main islands probably contain minerals of economic value. Gold has been found in Bougainville, New Georgia, Vangunu, and Guadalcanal. Tin has been reported in south Bougainville. Phosphate deposits, of poor quality, however, have been found on Rennell.