When volcanoes erupt and the lava cools to form igneous rock, the process normally entraps air and liquids which existed at the time of the rocks' formation.
(volcanoes; erupt; ) (the lava cools; to form; igneous rock) (the process; normally entraps; air and liquids; T:When volcanoes erupt and the lava cools to form igneous rock) (liquids; existed; T:at the time of the rocks' formation)
volcanoes the lava cools the process liquids
erupt to form normally entraps existed
igneous rock
air and liquids T:When volcanoes erupt and the lava cools to form igneous rock
T:at the time of the rocks' formation