Tuff and Pyroclastic Formations

This group collects the Volcanic Formations subcategory's members whose own description identifies them by their tuff, pyroclastic or ignimbrite rock, hardened deposits of volcanic ash and fragmented rock laid down by an eruption rather than by flowing lava. The fairy chimneys of Cappadocia and the tuff-ring islets of Samoa's Aleipata Islands group are among this small but distinct group's members, kept apart from the columnar basalt group because tuff forms from fragmented ash falling and consolidating, not from cooling, jointing lava.