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Cameroon line

earth science Maturity 7-9 Next article →

The Cameroon line is a massive, continuous chain of volcanoes.

Gulf of Guinea (English)
Gulf of Guinea (English)

It stretches from the Atlantic Ocean to the African mainland. The chain includes islands in the Gulf of Guinea and mountains near Lake Chad. It also forms a natural border between eastern Nigeria and the West Region of Cameroon. Geologists find this line unusual. This is because it extends through both the ocean and the continental crust.

Cameroon line
Cameroon line

In the ocean, the line creates six volcanic swells. Some of these swells are islands, while others are seamounts under the water. From the southwest to the northeast, the island groups are Annobón, São Tomé, Príncipe, and Bioko. On the mainland, the line begins with Mount Cameroon on the coast. It then moves northeast into the Western High Plateau. This plateau includes the Cameroonian Highlands forests. Further inland, the line includes the Manengouba, Bamboutu, and Oku Massif volcanoes.

biokoisland
biokoisland

Annobón is the southernmost island in the chain. It is an extinct volcano that rises from deep water. The island belongs to Equatorial Guinea. Its average temperature is 27°C, and it has very little seasonal variation. Most rain falls between November and May. São Tomé is a massive shield volcano. A shield volcano is a wide volcano built by flowing lava. It rises from the Atlantic floor, over 4,000 meters below sea level. The oldest rocks on São Tomé are 13 million years old.

sao tome forest
sao tome forest

Príncipe is a smaller island located near São Tomé. Volcanic activity on Príncipe stopped around 15.7 million years ago. The island has been deeply eroded over time. This erosion left behind spectacular towers of phonolite, which is a type of volcanic rock. Bioko is the largest island in the Cameroon line. It sits on the continental shelf near the coast of Cameroon. Bioko has three basaltic shield volcanoes. These volcanoes join together at their lower levels. One volcano, San Carlos, has a broad summit caldera. A caldera is a large crater formed when a volcano collapses.

São Tomé - Resort Pestana Equador
São Tomé - Resort Pestana Equador

Geologists have different theories about why this line exists. One major feature is the Central African Shear Zone. This is a long lineament, or structural feature, that runs under the mainland section. The coastline of the line roughly matches the Borborema province in Brazil. This connection exists because Africa and South America began to separate 115 million years ago. Some researchers believe the volcanoes are linked to this ancient separation. The shear zone is visible in the Foumban Shear Zone. This area was active during the Cretaceous period.

Cameroon line
Cameroon line

This volcanic activity has created many unique environments. Because islands like São Tomé and Príncipe were never connected to Africa, they have unique species. For example, São Tomé has 16 endemic bird species. Endemic means they are found nowhere else on Earth. Three species there are critically endangered: the São Tomé ibis, the São Tomé fiscal, and the São Tomé grosbeak. On the mainland, the high mountains are much cooler than the lowlands. This creates specialized habitats like montane forests.

Lake Oku Cameroon
Lake Oku Cameroon

The volcanoes also impact the land and people. Volcanism has created fertile black and brown soils. These soils are excellent for agriculture. People in the region grow cocoa, coffee, and palm products. On the mainland, the Western High Plateau is a major watershed. This means it is a region where water flows into many rivers. Important rivers like the Manyu and the Nkam rise here. These rivers provide water for much of Cameroon.

Menchum Falls NWprovince Cameroon
Menchum Falls NWprovince Cameroon

However, volcanic history can also be dangerous. In 1986, a crater lake called Lake Nyos released a cloud of carbon dioxide. This gas release killed at least 1,200 people. Mount Cameroon is also an active stratovolcano. A stratovolcano is a tall, conical volcano built by layers of ash and lava. Mount Cameroon erupted as recently as the year 2000.

Mount Cameroon craters
Mount Cameroon craters
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🖼️ Images & Media (8)
File:Gulf of Guinea (English).jpg
Gulf of Guinea (English).jpg
File:Mount Cameroon craters.jpg
Mount Cameroon craters.jpg
File:sao tome forest.jpg
sao tome forest.jpg
File:São Tomé - Resort Pestana Equador.jpg
São Tomé - Resort Pestana Equador.jpg
File:biokoisland.jpg
biokoisland.jpg
File:Lake Oku Cameroon.jpg
Lake Oku Cameroon.jpg
File:Menchum Falls NWprovince Cameroon.jpg
Menchum Falls NWprovince Cameroon.jpg
File:Cameroon line.svg
Cameroon line.svg
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