Madeira is a small Island, 57km from north to south, 22km from east to west, altogether 741 km². It lies on 17° west, 33° north in the northern Atlantic, about 600km west of Cassablanca. Madeira belongs to Portugal, but it has an independent status. The capital of Madeira is Funchal at the south eastern coast.
The volcanic island contains primarily of basaltic rocks. Its landscape is very rough, the highest Mountain is the Pico Ruivo, 1,861m high.
Madeira is famous for its vine. The Madeira wine is used for cooking or drinking, has an intensive bouquet. The exisitance of this wine needed three prerequisites: the climate, the diligence of the inhabitants and the geology of the islands.
The islands are lying in the middle of the Atlantic Ocean. The ground is here 3500 m below sea level. The islands are enormous volcanoes rising from the bottom of the sea a little bit more than those 3500m, and just the summit of every mountain is above the water level.
The volcanic rocks contain an overwhelming amount of nutrient minerals, so after erosion started and made those substances available to the plants, the volcanic earth is extremely fertile. The wine is only one of the numerous agricultural products of the islands.
The geology is obviously not suitable for karst and karst caves. But there are some lava tubes, one of them open as a show cave.
There are also numerous canals, built to transport water to the fields. Today they are not used any more, now they are popular trails for tourists. The canals sometimes had to be built through mountain sides, which made several tunnels necessary.