The Solomon Islands lie to the east of New Guinea and consist of an archipelago a thousand miles in length and about half this distance in breadth. They are divided politically into the Northern Solomons (formerly German but now administered under Mandate by Australia), and the British Solomon Islands Protectorate. This latter lies roughly between five and twelve degrees south of the equator and is believed to have been united both to New Guinea and Australia from at least the Triassic to the early Tertiary. As there is now a deep sea between the archipelago and the two land-masses, the former falls into the ancient section of the continental islands of Wallace.

The rainfall averages 150 inches, the maximum shade temperature has a mean of 90°F., and the relative atmospheric humidity averages 92 per cent.

The Group consists of six large islands ranging from 60 to 120 miles in length and many smaller ones, including the isolated Santa Cruz group to the east. The main islands are composed of both coralline and volcanic (chiefly diorite) rocks and hence exhibit a wide range of soil-types from coralline sands and red clay to alluvium. Evidence of former extensive elevation is provided in raised coral-beaches. The islands are generally covered with jungle and densely wooded to their summits which rise in places to over 8,000 feet. An exception to this is the central and western portions of the northern coast of Guadalcanal, which consist of grass plains and undulating downland.