extrusive intrusive volcano magma plutonic eruption hotspot extinct active dormant
LEARNING INTENTIONS
By the end of this chapter I will be able to: z z z z zz
Syllabus Link: 1.1, 1.2, 1.3
identify each part of a volcano’s structure from a diagram or photograph; identify all volcanic features from a diagram or photograph; explain the global distribution of volcanoes; zzexplain the three stages of a volcano’s life; zz zz
examine the processes involved in the formation of volcanic landforms; explain how volcanic activity can be predicted;
zzdescribe, using examples, the positive and negative results of volcanic activity.
Volcanic activity results in the formation of extrusive and intrusive features. z z
Extrusive features form on the earth’s crust when lava cools and solidifies quickly (Fig. 2.1).
z z
Intrusive features form within the earth’s crust when magma and gases cool and solidify slowly.
A-Z
Magma: Hot liquid rock and metals.
Volcanic: A term used to describe extrusive features.
Plutonic: A term used to describe intrusive features.
Volcanic Activity on the Earth’s Surface
1. Island arc (subduction zone)
2. Hotspot
3. Mid-ocean ridge (sea-floor spreading)
4. Volcanic arc (subduction zone)
5. Rifting
Mantle DID YOU KNOW?
About 80% of the earth’s surface, above and below sea level, originated because of volcanic activity.
14 Key Plate movement Fig. 2.1 Extrusive volcanic features and the locations where they form.
