The Canary Islands are a geologically captivating archipelago in the Atlantic Ocean, located approximately 100 kilometers off the northwest coast of Africa. This chain of seven main islands and several smaller islets represents a massive accumulation of volcanic material rising from the ocean floor. Since the islands are not located at a tectonic plate boundary, their formation is a unique case study of intraplate volcanism that has unfolded over millions of years.
The Dominant Theory: Hotspot Volcanism
The dominant scientific explanation for the Canary Islands’ existence centers on the persistent activity of a mantle plume, or geological hotspot. This theory proposes that volcanism is driven by a column of unusually hot rock rising from deep within the Earth’s mantle, which remains relatively fixed in place. The African Tectonic Plate, upon which the islands rest, is slowly drifting eastward across this stationary heat source.
As the African Plate moves at about one centimeter per year, the hotspot provides a continuous source of magma that punches through the overlying oceanic crust. This process results in sustained volcanic eruptions that build up seamounts from the seafloor until they break the ocean surface. The islands are the visible trail left behind by the tectonic plate’s movement over the deep-seated plume.
The age progression of the islands, with the oldest to the east and the youngest to the west, supports the hotspot track model. Although the mantle plume hypothesis is widely accepted, some researchers propose supplementary mechanisms. For example, crustal fractures extending from the nearby Atlas Mountains in Morocco could provide additional pathways for magma to rise, complicating the simple hotspot model.
This interplay between a deep mantle source and potential lithospheric weaknesses explains why the Canary Islands’ volcanism, while related to a plume, does not exhibit the perfectly linear age-distance relationship seen in other hotspot chains like Hawaii. The heat source remains a consistent anomaly beneath the plate, fueling the ongoing volcanic process that originally began over 70 million years ago beneath the ocean surface.
The Age Progression and Island Sequence
The islands to the east are significantly older than their western counterparts. Fuerteventura and Lanzarote, the easternmost islands, display the oldest subaerial volcanic rocks, with formation beginning around 20.2 million years ago. Having drifted away from the plume’s center, these islands show extensive erosion and a lower, subdued topography.
Moving westward, central islands like Gran Canaria and Tenerife show intermediate ages, having emerged from the sea between approximately 14 and 12 million years ago. Some have experienced renewed volcanism long after their initial shield-building phase. La Gomera is a notable example of an older island currently in a deep erosional stage, lacking any recent volcanic activity.
The active end of the chain is represented by the westernmost islands, La Palma and El Hierro, which are the youngest and still lie near the area of the most intense magmatic upwelling. La Palma began its subaerial phase around 1.7 million years ago, while El Hierro is the youngest at approximately 1.1 million years.
Unique Geological Features of the Archipelago
The islands are largely built upon massive shield volcanoes, which formed through the successive eruption of fluid, basaltic lava flows. These shield structures dominate the topography, exemplified by the vast basal series found across the archipelago.
One of the most impressive features is the presence of large calderas, which are massive collapse structures that formed after major eruptions emptied the magma chamber beneath. The Caldera de Taburiente on La Palma, for example, is one of the largest erosion calderas in the world. Another prominent feature is Teide, a towering stratovolcano built within the remnants of an older, massive collapse caldera on Tenerife.
Geological cross-sections reveal dense networks of vertical rock intrusions known as dike swarms, particularly visible in the Basal Complexes of older islands like Fuerteventura and La Gomera. These dikes are the solidified magma conduits that fed the ancient volcanoes and have been exposed by millions of years of erosion. The islands also exhibit a varied rock composition, ranging from primitive basaltic lavas to more evolved, silica-rich phonolites.
Present Day Status and Future Activity
The geological process is actively continuing today, primarily focused on the western end of the chain. La Palma and El Hierro remain the volcanically active centers, demonstrated by the 2021 eruption of Cumbre Vieja on La Palma and the 2011–2012 submarine eruption off the coast of El Hierro. These events confirm that the islands are still growing as new magma is supplied from below.
Seismic and volcanic monitoring networks track magma movement, ground deformation, and gas emissions across the western islands. This surveillance is necessary because the active hotspot means future eruptions are expected on the youngest islands. The long-term geological future involves a continuous cycle of new island formation to the west as the plate moves.
The older eastern islands will continue to be worn down by ocean and weather erosion, eventually sinking back beneath the waves over millions of years. Active volcanic centers will persist in building new land, ensuring the Canary Islands remain a dynamic example of hotspot volcanism.