Download Why do volcanoes erupt?

Why do volcanoes erupt?
Student task
Discard one statement from the cards below and rearrange them to obtain the correct
sequence at either a) a constructive or b) a destructive plate margin.
Over millions of years, these layers of lava form a volcano.
When lava erupts on the surface, it cools to form hardened layers.
The Earth’s tectonic plates are constantly moving.
Magma is a mixture of molten or semi-molten rock, solid rock and gases formed from
the partial melting of the crust and/or mantle.
Most of the world’s 550 active volcanoes on Earth are located along the margins of
adjacent plates.
When two plates collide at a destructive plate boundary, subduction will occur and
magma may rise to the surface.
The earth is composed of three distinct layers: the crust, mantle, and core.
Magma can be squeezed up between two plates at a constructive plate boundary.
The Earth's crust is made up of a dozen or so major plates and several minor plates,
which fit together like a jigsaw puzzle.
Extension tasks
1. Name three of the Earth’s plates.
2. What is the difference between magma and lava?
3. Which of these four rocks is a form of lava?
basalt
granite
limestone
slate
4. Name and locate three volcanoes.
© www.teachitgeography.co.uk 2015
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Why do volcanoes erupt?
Teaching notes/suggested answer
The following sequence suggests two possible answers relevant to either a constructive
or a destructive plate margin.
The earth is composed of three distinct layers: the crust, mantle, and core.
The Earth's crust is made up of a dozen or so major plates and several minor plates,
which fit together like a jigsaw puzzle.
The Earth’s tectonic plates are constantly moving.
Magma is a mixture of molten or semi-molten rock, solid rock and gases formed from
the partial melting of the crust and/or mantle.
Most of the world’s 550 active volcanoes on earth are located along the margins of
adjacent plates.
Magma can be squeezed up between
two plates at a constructive plate
boundary.
When two plates collide at a destructive
plate boundary, subduction will occur and
magma may rise to the surface
When lava erupts on the surface, it cools to form hardened layers.
Over millions of years, these layers of lava form a volcano.
Extension tasks
1. A useful map of the Earth’s tectonic plates is available at
http://pubs.usgs.gov/gip/dynamic/slabs.html
2. Magma is formed from partial melting of the crust and/or mantle. Lava is an
extrusive surface rock.
3. Basalt is a lava – an extrusive igneous rock, granite is an intrusive igneous rock,
limestone is a sedimentary rock and slate is a metamorphic rock.
© www.teachitgeography.co.uk 2015
24018
Page 2 of 2