Igneous Rock Formation

Dolerite dykes and sills, Karoo

Basalt

Formation of Columnar Basalt and the Rock Cycle/Tectonic Processes

This video gives a really good description of the formation of the Devil's Tower in the USA. However, the same type of Rocks can be found on the back of Mt Cargill, and are known as the Organ Pipes.

Best if you watch from about 1 minute.

Andesite

Formation of Andesite