Vent 21
Vent 21 : The opening at the Earth's surface through which volcanic materials (lava, tephra, and gases) erupt. Vents can be at a volcano's summit or on its slopes; they can be circular (craters) or linear (fissures). (Teacher's Packet). An opening in the Earth's surface through which volcanic materials (magma and gas) escape. (Gardner, et.al., 1995)