Basalts with Columnar Disjunctions at Reynisfjara Beach, Iceland

Photographer: Carlos di Nallo
Summary Author: Dr. Jose Pablo Lopez 

Columnar structures such as the above, photographed at Reynisfjara Beach, Iceland, are produced when a lava flow cools slowly, changing from a liquid to a solid state, which produces a strong contraction in all directions in the material. As its volume decreases, fractures form and propagate from the exterior to the interior. This cooling and contraction process occurs from different centers at the same time, and the fractures thus generated intersect each other, resulting in the characteristic polygonal patterns. They're vaguely hexagonal due to the homogeneity of the rock and the heat loss gradient. Basaltic magmas cool to approximately 980 to 950 degrees C, and when they do so at exposed surfaces these columnar structures form in a nearly solid state. Photo taken on September 15, 2023.

Photo Details: Canon 6D camera; Canon lens 17/40 mm; 1/100second exposure; ISO 200.

Reynisfjara Beach, Iceland Coordinates: 63.4044 -19.0692

Related Links:
Iceland’s Basalt Columns: Nature’s Artwork
List of places with columnar jointed volcanics