Geologically, the formation of Madagascar is explained differently. It seems to be certain that the island broke away from the African continental mass in the course of the continental drift when the supercontinent Gondwana broke up around 270 million years ago and drifted to the southeast. The island is therefore also referred to as the “Old Island” by geologists. Where exactly Madagascar was located as part of Africa is not sufficiently proven. The hypothesis created in the course of zoological studies in the 19th century, which describes the existence of a sunken continent called Lemuria, the remains of which Madagascar and the Seychelles to the north of the island would be considered to be, is now unconfirmed. Most of Madagascar consists of a crystalline foundation made of gneiss, mica schist, quartz and granite, which is interpreted as part of Gondwana and runs through the island from north to south. In the central part of Madagascar, these very old rocks form an extensive, geomorphologically varied high plateau of valleys, plains and rivers, of which several mountains form prominent elevations in this north-south mountain range. These include the Maromokotro volcano (2,876 m) in the north and the Pic Boby (2650m) in the south. The Ankaratra Mountains are located in the northern central highlands with a maximum height of 2,600 m. The plateau is bordered in the south by the Andringitra Mountains, a granite rock mountain range over 2000 m high.
The slow rise of the plateau from the west and the steep and rapid decline to the east are remarkable, with the sea depth increasing very quickly east of the coast, while shallower waters predominate in the west and south of the island.
Although many areas of Madagascar appear rather dry at first glance, the country is rich in water and criss-crossed by rivers and lakes. In the interior of Madagascar there are five large inland lakes: Lake Alaotra east of Antananarivo and, with 55,000 hectares, the largest lake in Madagascar, Lake Itasy in the northern central highlands, Lake Kinkony in the west and Lake Ihotry and Tsimanampetsotsain the south or southwest. The latter is a salt lake (the name means “lake without dolphins”) and is located in one of the driest regions of the island; at the same time he is the namesake for the Tsimanampetsotsa National Park. The lakes are drinking water reservoirs, are used for irrigation and also act as fish suppliers. The larger rivers such as the Ikopa (485 km), the Tsiribihina, the Mangoky (564 km) and the Betsiboka have their source in the eastern part of the highlands and flow into the sea on the west coast. An artificial waterway is the Canal des Pangalanes, which connects various natural lakes and streams and runs parallel to the east coast of Madagascar. At 645 km, the canal is one of the longest man-made waterways in the world.
According to aristmarketing, Madagascar can be roughly divided into five different landscape zones or regions:
- The central highlands are characterized by hills, mountains, valleys, lakes and many rivers and various types of vegetation. It extends over the entire length of the island of approx. 1500 km and reaches heights of 800 to 1800 m. To the north of Antananarivo, the highlands are almost treeless for several hundred kilometers. The extensive and important riceand vegetable cultivation areas of Madagascar are also located here. The primary forest has been reduced to a few remains. The northern part is characterized by large grazing areas. Due to the altitude, the temperatures are moderated and can also drop below freezing point in the months of southern winter.
- In the north,in the area of the coast, there are mighty mountain bases, primary forest areas and lakes that are of volcanic origin. Because of the comparatively fertile soils, sugar cane is grown in addition to rice.
- Primary rainforest areas, which still prevail here due to the high levels of precipitation and temperatures, are home to many endemic animal and plant species in eastern Madagascar. Tropical crops such as vanilla, coconut palms, cloves, coffee and cocoa also thrive in this region facing the wind. Overall, the northeast is even more rainy than the southeast. Road transport is difficult because of the many waterways; the trip on the Canal des Pangalanes offers an alternative, but it is leisurely and not for those in a hurry.
- The southwest is the hottest and driest region of Madagascar, in some places there are deserts. Aside from sisal plantations, only a small amount of arable farming is possible; the areas are mainly used for pasture farming. Many succulents endemic to Madagascar and interesting for the botanist grow here.
- Overall, the west coast is characterized by the fact that it is relatively little developed. In a narrower sense, the area between Mahajanga in the north and Morondava in the south is humid with pronounced dry periods in the southern winter, with the north receiving around 1500 mm of precipitation, but the south only 300 – 400 mm. Except for the very dry areas, the west can be used for agriculture. Cotton, tobacco, sugar cane, vegetables and bananas are sometimes grown in large plantations. Pastures are often burned down, and much of the natural vegetation is no longer available today. Mangrove forests grow on the coast. The impressive karst landscape of is a UNESCO World Heritage Site Tsingy de Bemaraha in the Mahajanga Province, a geological feature in Madagascar that also attracts many tourists from all over the world.