Geograph - photograph every grid square

Columnar Basalt

Contrary to what we were told on the boat, there are only two major lava flows in the Staffa Formation. The smooth-looking underlying rock under the columns is the older flow. The columns are the lower part and the maze of shapes above, termed the entablature, are parts of the same flow. Most columnar basalts would originally have an entablature. The difference is related to how close the cooling lava is to the surface of the Earth.