French Guiana

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French Guiana

French Guiana, the most easterly of the three Guianas, is the only French continental possession in the Americas. The colony is roughly rectangular in shape, comprising about 34,740 square miles.

French Guiana is divided into a series of roughly parallel belts or zones, generally aligned in a northwest-southeast direction. Low rocky islets (including the Iles du Salut, the infamous Ile du Diable, Ile Royale, and others) fringe the coast. In some places near the shore hills about 500 feet high improve the drainage possibilities for town sites. Inland from these low hills and from the ocean stretches a marshy area from 15 to 25 miles wide, beyond which there is a low hilly belt along the line between French Guiana proper and Inini. The unexplored and very sparsely settled interior is a low plateau extending about 125 miles inland to a range of hills approximately 1200 feet high. On the Brazilian boundary line are the 2500foot Tumuc Humac Mountains.

The geologic structure is little known: the bedrock is granitic and most of the formations are crystalline. The lowlands are covered to a great depth with recent alluvium.

CLIMATE AND VEGETATION

The climate is probably the greatest single physical handicap. The mean annual temperature at Cayenne (sea level) is 80° F., and there is little difference in the temperatures between any two months. The year-round high temperatures, together with a relative humidity averaging about 90 per cent, make for a very enervating and monotonous climate. The average rainfall on the coast is a little more than 130 inches a year, but in the interior, especially in the higher sections, the average is even higher (in places approximately 170 inches a year). There are two rainy seasons: May through July and November through January. February and March are the dry months, when occasional droughts occur. Onshore winds bring some relief to the warm coastal districts. French Guiana is not in the hurricane track.

The natural vegetation may be divided into three general types. Along the coast and at the mouths of the rivers, mangrove thickets and a typical marsh vegetation prevail. Farther inland in the lower areas extensive savanas cover about 740,000 acres. Beyond these, on the uplands, is a tropical rain forest, which contains many valuable species of trees.

The dense forests have been a great handicap in the penetration of the interior, where the rivers are practically the only highways. More than 20 large rivers flow generally from the southern highlands northward to the coast, but they are difficult to navigate because of many falls and rapids. In the lower areas the rivers are in flood during the wet seasons and frequently shift their courses.