EXTRUSIVE VOLCANIC FEATURES

You need to have illustrated notes / definitions of the following areas / topics.

Each should take up no more than a third of a page.

Try to include named and located examples where relevant.

1. Magma is known as lava once it reaches the surface of the earth. How does magma actually make its way onto the surface of the earth ? How does it get through the crust, and what forms can the opening in the crust take ?

2. When magma reaches the surface, it produces different shaped cones depending on its nature. What are meant by the following cones (provide description, example, and picture if possible.)

a) acid cone

b) basic cone

c) composite, or strato-volcano

d) caldera

You will need to use information about the different types of lava to answer this question. Suggest you need to consider the viscosity of the lava, which will affect its speed of flow. Difference between felsic and mafic lavas.

4. Describe the feature called a 'lava plateau'. What sort of area do these features cover, and how are they created ? Use a named/located example.

5. There is a wide range of material ejected during volcanic eruptions. What are the following ?

a) lapilli

b) pumice

c) fumaroles

d) pyroclastic flows

e) lahars

6. What economic benefits are there of living in tectonically active areas i.e: close to volcanoes ?

Try to discover what the population of Iceland gain from living on an island which straddles the Mid-Atlantic Ridge. e.g geothermal energy, tourist income, Blue Lagoon etc.

Try the USGS site here for some particular details on LAHARS.

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