Geography of Guadeloupe

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Guadeloupe is an archipelago of more than 12 islands, as well as islets and rocks situated where the northeastern Caribbean Sea meets the western Atlantic Ocean. It is located in the Leeward Islands in the northern part of the Lesser Antilles, a partly volcanic island arc. To the north lie Antigua and Barbuda and the British Overseas Territory of Montserrat, with Dominica lying to the south. The two main islands are Basse Terre (west) and Grande Terre (east), which form a butterfly shape as viewed from above, the two 'wings' of which are separated by the Grand Cul de Sac Marin, Rivière Salée (Guadeloupe) and Petit Cul de Sac Marin. More than half of Guadeloupe's land surface consists of the 847.8 km2 Basse Terre. The island is mountainous, containing such peaks as Mount Sans Toucher (4,442 feet; 1,354 metres) and Grande Découverte (4,143 feet; 1,263 metres), culminating in the active volcano La Grande Soufrière, the highest mountain peak in the Lesser Antilles with an elevation of In contrast Grande Terre is mostly flat, with rocky coasts to the north, irregular hills at the centre, mangrove at the southwest, and white sand beaches sheltered by coral reefs along the southern shore. The western half is part of an active volcanic arc that extends from Saba to Grenada. The eastern half is part of an older extinct volcanic arc that includes Anguila, Saint Martin, Saint Barts, Barbuda, Antigua, Grand Terre and Marie Galante. Here the mountains are worn down and the soil is mostly coral limestone. Because of the porous soil and lack of mountains to catch rainfall, agriculture is limited by insufficient water. Basse Terre is a volcanic island. The Lesser Antilles are at the outer edge of the Caribbean Plate, and Guadeloupe is part of the outer arc of the Lesser Antilles Volcanic Arc. Many of the islands were formed as a result of the subduction of oceanic crust of the Atlantic Plate under the Caribbean Plate in the Lesser Antilles subduction zone. This process is ongoing and is responsible for volcanic and earthquake activity in the region. Guadeloupe was formed from multiple volcanoes, of which only La Grande Soufrière is not extinct. Its last eruption was in 1976, and led to the evacuation of the southern part of Basse Terre. 73,600 people were displaced throughout three and a half months following the eruption. K–Ar dating indicates that the three northern massifs on Basse Terre Island are 2.79 million years old. Sections of volcanoes collapsed and eroded within the last 650,000 years, after which the Sans Toucher volcano grew in the collapsed area. Volcanoes in the north of Basse Terre Island mainly produced andesite and basaltic andesite. There are several beaches of dark or "black" sand. La Désirade, east of the main islands, has a basement from the Mesozoic, overlaid with thick limestones from the Pliocene to Quaternary periods. Grande Terre and Marie Galante have basements probably composed of volcanic units of Eocene to Oligocene, but there are no visible outcrops. On Grande Terre, the overlying carbonate platform is 120 metres thick. |date=September 2011

With fertile volcanic soils, heavy rainfall and a warm climate, vegetation on Basse Terre is lush.

In recent decades, Guadeloupe's natural environments have been affected by hunting and fishing, forest retreat, urbanization and suburbanization. They also suffer from the development of intensive crops (banana and sugar cane, in particular), which reached their peak in the years 1955–75. This has led to the following situation: seagrass beds and reefs have degraded by up to 50% around the large islands; mangroves and mantids have almost disappeared in Marie Galante, Les Saintes and La Désirade; the salinity of the fresh water table has increased due to "the intensity of use of the layer"; and pollution of agricultural origin (pesticides and nitrogenous compounds). In addition, the ChlEauTerre study, unveiled in March 2018, concludes that 37 different anthropogenic molecules (more than half of which come from residues of now banned pesticides, such as chlordecone) were found in "79% of the watersheds analyzed in Grande Terre and 84% in Basse Terre." A report by the Guadeloupe Water Office notes that in 2019 there is a "generalized degradation of water bodies." Despite everything, there is a will to preserve these environments whose vegetation and landscape are preserved in some parts of the islands and constitute a sensitive asset for tourism. These areas are partially protected and classified as ZNIEFF, sometimes with nature reserve status, and several caves are home to protected chiropterans. The Guadalupe National Park was created on 20 February 1989. In 1992, under the auspices of UNESCO, the Biosphere Reserve of the Guadeloupe Archipelago (Réserve de biosphère de l'archipel de la Guadeloupe) was created. As a result, on 8 December 1993, the marine site of Grand Cul de sac was listed as a wetland of international importance. The island thus became the overseas department with the most protected areas.

The archipelago is crossed by numerous geological faults such as those of la Barre or la Cadoue, while in depth, in front of Moule and La Désirade begins the Désirade Fault, and between the north of Maria Galante and the south of Grande Terre begins the Maria Galante Fault. And it is because of these geological characteristics, the islands of the department of Guadeloupe are classified in zone III according to the seismic zoning of France and are subject to a specific risk prevention plan. The 1843 earthquake in the Lesser Antilles is, to this day, the most violent earthquake known. It caused the death of more than a thousand people, as well as major damage in Pointe à Pitre. On 21 November 2004, the islands of the department, in particular Les Saintes archipelago, were shaken by a violent earthquake that reached a magnitude of 6.3 on the Richter scale and caused the death of one person, as well as extensive material damage.