A journey from the earth's interior to the surface
The island of Leka is Norway’s Geological National Monument and displays a section through the oceanic crust better than anywhere else in the world. You can actually walk or cycle on the interior of the Earth. Leka was formed in a mid-oceanic ridge close to Laurentia (America) 500 million years ago. A fragment of the oceanic crust was then forced up on land when America and Europe collided 400 million years ago.
The reddish-yellow bedrock that is so characteristic for Leka is ultramafic rock formed in the deepest part of the oceanic crust and the underlying mantle. Here you can see the MOHO, the boundary between the mantle and the crust.