noun
intrusive rock
Geology term for rock formed from magma that cooled and solidified beneath the Earth's surface.
花崗岩は代表的な貫入岩です。
Granite is a typical intrusive rock.
火山岩 (volcanic rock) forms from lava on the surface, while 貫入岩 forms underground.
Compound of 貫入 (intrusion) + 岩 (rock).