Their existence contradicts the common assertion the Earth’s mantle is well-mixed, suggesting our models are wrong.

The Hawaiian Islands, which are entirely volcanic in origin, formed in the middle of the Pacific Ocean, more than 3,200 km from the nearest plate boundary. This is explained by the 'hotspot' theory.

but are located more than 3,200 kilometres from the nearest plate boundary. This is explained by the 'hotspot' theory. Key fact The 'hotspot' theory is that there are fixed spots in the mantle ...