Assertion: volcano's magma | /r/HasProperty | molten underground rock
Facets:
Source sentences:
text: Sometimes beginning with an accumulation of gas-rich magma (molten underground rock) in reservoirs near the surface of the Earth, they can be preceded by emissions of steam and gas from small vents in the ground.
text: At the margins of Earth's plates, where two plates pull apart or one plate dives beneath another, magma (molten underground rock) frequently rises to the surface through volcanic vents.