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SECTOR 7

THE SOLOMON ISLANDS—EAST PART

7.0

Plan.—This sector, covering the E islands of the Solomons,

describes the island of San Cristobal, including the islands and dangers N and SW of it, then the island of Malaita, and then Indispensable Strait. Guadalcanal Island is next discussed, followed by the Florida Islands, the Russel Islands, and finally Buka Island. The general arrangement of this sector is from SE to NW.

General Remarks

7.1 The Solomon Islands, between 5°S and 13°S, and

154°30'E and 162°45'E, extend over an area 600 miles long in a NW-SE direction and up to 100 miles wide. They include seven major islands and between 20 and 30 smaller islands and numerous islets. The seven major islands are San Cristobal, Malaita, Guadalcanal, Santa Isabel, Choiseul, New Georgia, and Bougainville, the first three of which are discussed in this sector and the remainder in Sector 8. The group consist of a double row of large mountainous islands attaining heights, as in the case of Guadalcanal and Bougainville, of 2,439 to 3,048m.

7.1

In appearance the islands present many similar character-

istics, consisting of a chain of lofty mountains, mostly covered with dense forest and rank undergrowth, occasionally giving place to long grass and ferns. The slopes incline gently to the sea, and the shores are lined with mangroves in places. The larger islands are watered by numerous streams, at the

7.1

mouths of which, as well as on the swamps and sandy shores of uninhabited coral islets, crocodiles abound.

7.1

Some of these islands are entirely of volcanic formation,

while others are calcareous, but there are also many cases in which both these formations are combined.

7.1

Mount Bagana and Mount Balbi, on Bougainville Island, are

active volcanoes, and Savo, Simbo, and other islands some- times exhibit signs of latent activity. Fumaroles and hot springs occur in several islands, and around these deposits of sulphur, alum, gypsum, and opal may be found. Earthquakes are com- mon in these islands.

7.1

Winds—Weather.—In the Solomon Islands, the Southeast

Trades are usually established in April and continues until the end of October; during this season more than 75 per cent of the winds are E, and 60 per cent are from E to SE. The trade is steadier and stronger over the S part of the group.

7.1

From November to April, the winds blow predominantly

between the NE and NW, though great variability marks this season, and appreciable percentages of E and S winds occur. Winds of storm force are practically unknown. Very few tro-

7.1

pical cyclones, mostly at early stages, have affected this area. The season of the Southeast Trades is drier than the remainder of the year, although ample rainfall occurs even with the trade winds, but from December to March the rainfall is exceedingly heavy. Thunderstorms are frequent during the latter period and fairly common otherwise, except that they are infrequent at the heart of the trade in July and August.

In the vicinity of the larger islands the winds are affected by land and sea breeze influences.

7.1 7.1

May to October is the drier season of the year, with rainfall

averaging about 125mm per month. During the rest of the year it averages 230mm to 265mm with March being the wettest at over 310mm of rainfall. What is lacks in rainfall however, it makes up for in humidity. July to September the humidity is about 73 per cent rising to a maximum in March of 80 per cent. Average temperature the year around is between 26°C and

7.1

27°C, making it one of the most consistent climates the year around.

7.1

Tides—Currents.—The South Equatorial Current and the

South Subtropical Current, the major prevailing surface cur- rents in the area of the Solomon Islands, set W across the Pacific Ocean under the influence of the Southeast Trades, the strength of which gradually decreases with increasing S lat- itude.

7.1

From October through March, during the Northwest Mon-

soon, part of the South Equatorial Current turns S and SE along the NE coast of New Guinea, but this monsoon does not reach the Solomon Islands in any appreciable extent in February when it is strongest. During this time the current may become South.

7.1

From April through September, during the Southeast Trades,

part of the South Subtropical Current flows through the Solo- mon Islands, but being influenced by the wind has a consider- able degree of variability.

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During the Northwest Monsoon, the average velocity of the

current is about 0.8 knot; during the Southeast Trades, it aver- ages about 1 knot.

7.1

Caution.—Extensive lines of barrier reef occur in parts of

the Solomon Islands, as off the E coast of New Georgia, Santa Isabel Island, and the S coast of Choiseul Island. Some of these, as well as the greater portion of the islands, are still not completely surveyed; a great deal of caution is necessary when navigating among the group. No reliance should be placed on lights in the Solomon Islands; some are frequently unlit. Lighted structures on the reefs may be washed away and those on land may become obscured by trees.

Islands and Dangers North and Southwest of San Cristobal Island

7.2 The Indispensable Reefs (12°36'S., 160°20'E.), with

their center about 160 miles SW of the E extremity of San Cristobal, are three reefs stretching more than 60 miles in a NW-SE direction. They are steep-to and each encloses a large deep lagoon. They are separated by deep passages 1.5 to 2 miles wide.

7.2

South Reef (12°55'S., 160°33'E.) is 13 miles long and about

5 miles wide; it encloses a lagoon with depths from 18 to 35m. It is reported to be a poor radar target. A wreck is beached on the NE side of the reef.

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