noun
volcanic spine
A geological term for a steep-sided, pillar-like protrusion of solidified lava or volcanic rock, often formed by erosion of surrounding material.
火山岩尖は、火山活動の後に残る鋭い岩の突起である。
A volcanic spine is a sharp rock protrusion left after volcanic activity.
Compound of 火山 (kazan, 'volcano') + 岩 (gan, 'rock') + 尖 (sen, 'point, sharp tip'). The exact historical derivation is uncertain; the term is a modern geological coinage.