GEOG 2110L Lecture : VOLCANISM.docx
17 Mar 2014
School
Department
Course
Professor
Document Summary
* the processes by which magma and gases are transferred from the earth"s interior to near or on the surface. * 2 basic types: extrusive vs intrusive volcanism. Extrusive: when magma (lava) flows out onto the earth"s surface and then cools to form igneous rock. * volcano: a landform with a vent, or fissure(crack) on the surface which is the end of a conduit originating from below the crust in the asthenosphere. * often a mountain landform (fissures usually do not form features of high relief) * magma originating in the asthenosphere is expelled through the conduit & out the vent. * magma often collects in a magma chamber below the volcano before being expelled. * crater: the surface depression at the summit of the volcano. Active: currently erupting, or has erupted during recorded history. Dormant: an active volcano that is in repose but is expected to erupt in the future.
