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Structure of the earth menu
Structure of the earth
Continental Drift and Plate tectonics
Plate boundaries


Destructive Plate Margins Constructive Plate Margins

Pacific Ring of Fire

Fold Mountains

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[image - cross section of the earth]
A cross section of the earth

Constructive Plate Margins

Online Activities
[Online activities]: n Activities related to this topic
Volcanoes - Fling the teacher game
Tectonics Grade or No Grade Game
This activity is provided by our sister site www.interactivegeography.co.uk and will pop up in a new window
[Podcast]: n Audio file for playback on mobile devices and personal computers


A construtive (tensional) plate boundary happens where plates move apart. Most of these plate margins are under the oceans. As the plates move apart magma rises from the mantle to the earth's surface. the rising magma forms shiled volcanoes.

destructive plate margin

figure 1. Cross section of a conservative (tensional) plate margin (source: Wikipedia)


Constructive (tensional) plate margins occur where plates move apart. Examples below include the South American Plate and African Plate and the Eurasian Plate and the North American Plate.

Iceland was formed as the result of sea floor spreading in the North Atlantic. The image below illustrates this.

The formation of Iceland

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