A 1,600 km volcanic chain that defies geological explanation

Countries & Cities · Published 30 September 2026 · Updated 25 October 2026 Swipe more like this →

In short: Stretching from the African mainland to the Gulf of Guinea, the Cameroon line is a geological anomaly. This chain of volcanoes spans both ocean and continental crust, leaving scientists divided over whether a deep mantle plume or ancient tectonic fractures are responsible for its creation.

The Cameroon line is a massive 1,600 km volcanic chain that forms a natural boundary between eastern Nigeria and Cameroon's West Region. It includes a series of islands in the Gulf of Guinea—such as Bioko, Príncipe, and São Tomé—and mainland mountains like Mount Cameroon and the Oku Massif. This structure is geologically unusual because it extends through both the oceanic and continental crust.

The origins of this magmatic activity are a subject of intense scientific debate. One prominent hypothesis suggests a mantle plume has existed in the region for roughly 140 million years, potentially remaining stationary under the Oca area since 66 million years ago. Proponents argue this heat source thinned the crust and facilitated rifting. However, this theory is contested by scientists who argue that the region's features do not align with plume predictions, suggesting instead that magma might leak from reactivated Precambrian faults or rise from deep-seated African low-shear-velocity provinces.

The line's impact on biodiversity is profound. Because islands like São Tomé and Príncipe have never been connected to the mainland, they host unique species, including the bright yellow Schistometopum thomense caecilian and several vulnerable bird species. On the mainland, the Western High Plateau creates a vital watershed, though human activity has shifted the landscape from dense forests to the Sudan savanna. The region also holds significant history, as the 4,095 m Mount Cameroon may have been seen by the explorer Hanno the Navigator in the 5th century BC.

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