Some 'benches' form differently by the rolling down of a long flap of wall lining. Gradations can occur, eg. where a thin bench breaks free and starts to roll downwards. Bioclastic Containing grains composed of fragmented and transported organic material, eg. shell fragments. A valley that is closed off at its downstream end, all its water sinking at or near that point. Strictly, a cave formed by gas pressure pushing up a surface crust.
True blisters are rare, and generally too small to enter.
Some large ones are known overseas. The term has been misused locally for lava caves that are single simple chambers formed by localised drainage of liquid lava from beneath 'stony rises'. A large fragment of volcanic ejecta. Breadcrust' and 'cowpat' bombs are named for their appearance. Bryozoa 'Lace corals', a fossil that was common in warm shallow Tertiary seas.