The Madeira archipelago is part of an underwater mountain range that lies directly on the African Plate. In terms of geological history, Madeira is a relatively young island, created in the course of several different periods of volcanic activity.
The fact that the rivers of the island have a steep gradient and take a straight route to the sea without meandering bends is a telltale sign of this.
The coasts of the island are steep and rocky, gradually plummeting down to 4,000 metres (2.5 miles) below sea level. The archipelago of Madeira was most likely created by a so called hot spot, a volcanically active area far from tectonic plate boundaries.
The visible part of the island rising above the sea is only a part of a much larger underwater volcanic system.
What is a hot spot?
Hot spots are areas of volcanic activity that are not located at tectonic plate margins and may occur in the middle of continents or oceans. A well known example is Hawaii. For a long time scientists had difficulties explaining this activity until the hypothesis of Tuzo Wilson in 1963, which states that there are smaller areas in the mantle of the Earth where magma is produced. If a tectonic plate (that floats on the Earth’s mantle) stays above such a spot for a long period of time, an underground volcano is created which leads to the creation of an island. A hot spot is therefore an almost stationary centre of volcanic activity. Hot spots may have a diameter of approx. 100-150 km (62 to 93 miles) and may create whole strings of islands.
The archipelago of Madeira is likely to be a part of a more than 70 million years old hot spot trace which extends to the North-East Atlantic in the form of several larger seamounts. These underwater mountains rise steeply from the ocean floor and are home to complex marine communities. Seamounts offer protection for many sea creatures and are an important nursery for many fish species. The first island of the archipelago of Madeira to be created was Porto Santo, around 11 to 14 million years ago.