Natural History Photographs

The rock cycle
Extrusive igneous rocks

These are probably basalts, but this cannot be determined with certainty from only a photo.
þorlákshöfn, Iceland; 27 July 2014.

When lava cools rapidly, cracks at an angle of ca. 120° release most energy. As a result, hexagonal columns as seen here can be observed in many places. Svartifoss, Iceland; 20 July 2014.

Mont Gerbier de Jonc (Ardèche), France; 28 July 2011. A lava dome, formed by highly viscuous lavas that hardly flow.

Huge solidified lava walls, south of Borgarbyggð, Iceland; 24 July 2014.

These collumnar basalts are on the mid-oceanic ridge, where the North American plate and the Eurasian plate spread apart. þingvellir, Iceland; 17 & 21 July 2014.