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ICSE-IX-Geography

07: Volcanoes

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    Section : I
    Short Answer Questions
  • Qstn #1
    What are known as volcanoes ?
    Ans : Volcanoes are the vents in the earth’s crust erupting hot magma from the interior core motivated by endogenic forces.
  • Qstn #2
    What is the difference between magma and lava ?
    Ans : Molten material moving under the earth’s crust is called magma. When magma comes to the surface of the earth it is known as lava.
  • Qstn #3
    Give one example each of an active volcano and a dormant volcano.
    Ans :

    1. Active Volcano - Mt. Stromboli and Mt. Etna in Italy

    2. Dormant Volcano - Mt. Kilimanjaro of Africa.
  • Qstn #4
    What is the difference between dormant volcano and an extinct volcano ?
    Ans : Dormant volcano can erupt at any interval but extinct volcano can never erupt again.
  • Qstn #5
    What is the magma chamber of a volcano ?
    Ans : The magma chamber is created by the molten magma itself by melting the surrounding rocks in the form of a huge chamber.
  • Qstn #6
    Name two types of landforms made by volcanoes.
    Ans : Two types of landforms are :
    1. Extrusive landforms: Extrusive landforms include crater composite cones caldera lava platforms.
    2. Intrusive landforms: Intrusive landforms include dykes batholiths laccoliths volcanic hill etc.
  • Qstn #7
    What is called the Pacific Ring of Fire ? Why is it called so ?
    Ans : There are 80% active volcanoes around the Pacific ocean which is called the Ring of Fire.
  • Qstn #8
    Name the three types of volcanoes on the basis of the frequency of their eruption.
    Ans : There are three types of volcanoes e.g. active volcano which is still active in erupting magma dormant volcano which erupts in uncertain intervals and extinct volcano which has stopped eruption permanently it is also called dead volcano.
  • Qstn #9
    What are known as Shield volcanoes ?
    Ans : A volcanoes erupting with plentiful lava spreading over the surface into several kilometres with huge circumference and taking a shape of shield are called as shield volcanoes.
  • Qstn #10
    Mention any two extrusive landforms caused by volcanic eruptions.
    Ans :

    1. Composite cone : The volcano which erupts both lava and pyroclastic rocks form alternating layers of these two materials and build up to form composite cones. Examples : Fujiyama in Japan Vesuvius and Stromboli in Italy.

    2. Caldera : During repeated eruptions the summit of a volcano may be blown up. In its place a large depression called caldera is formed. These are generally formed when the magma chamber is no longer able to emit sufficient magma and results in the collapse of a cone either partly or wholly.
  • Qstn #11
    Name any two intrusive landforms made by volcanic eruptions.
    Ans :

    1. Batholiths : Large sized intrusions in igneous rocks. They occur at considerable depth and come to the surface in course of mountain building activity.

    2. Laccolith : These are formed when magma spreads laterally in a dome shape. The dome also forces the overlying strata to bulge upward. The projecting landform is subjected to erosion and denudation. Thus laccolith comes to the surface.
  • Qstn #12
    How are hot springs formed ?
    Ans : The movement of magma heats up the underground water which converts into steam and gushes out through any crack or holes on the crust.
  • Qstn #13
    What is called the Pacific Ring of Fire ? Why is it called so ?
    Ans : There are 80% active volcanoes around the Pacific ocean which is called the Ring of Fire.
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