evidence: French Guiana, overseas territorial collectivity of France, situated on the northeastern coast of South America. French Guiana is bounded by Brazil to the south and east, Suriname to the west, and the Atlantic Ocean to the northeast. The capital is Cayenne. Geologically, the rock underlying French Guiana forms part of the crystalline massif of the Guiana Highlands. Rivers—which flow generally northeastward, to the sea—have greatly eroded the massif, and most of French Guiana is low-lying. The Maroni River forms the French Guiana–Suriname border in the west, and the Oyapock River forms the border with Brazil in the east. The Tumuc-Humac Mountains in the south reach an elevation of 2,300 feet (700 metres). Recent alluvial deposits have formed a swampy coastal plain southeast of Cayenne. Older alluvial deposits form a savanna west of Cayenne. Dense tropical forests (mostly hardwoods) predominate outside the coastal plain and cover more than nine-tenths of the land area. [...] French Guiana has a developing market economy, patterned on that of metropolitan France and sustained by aid and technical assistance from France. A rocket-launching base at Kourou, used by the European Space Agency, is of great importance to the economy, accounting for about one-fourth of the country’s annual gross domestic product (GDP). Services, manufacturing, and construction are the largest sectors of the economy. The gross national income (GNI) per capita is among the highest in South America.