CBSE Class 7 Geography Our Changing Earth Worksheet Set A

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INTERNATIONAL INDIAN SCHOOL,JEDDAH

CH-3: OUR CHANGING EARTH

WORKSHEET

Class: VII

Subject: Geography

TICK THE CORRECT ANSWERS :

Question. Alfred Wegener proposed that millions of years ago , there was a super-Continent called-
1] Africa
2] Pangaea
3] Asia
4] Gondwanaland
Answer : [ 2 ]

Question. Which of the following is an active Volcano -
1] Kilmanjaro
2] Mt.Kea
3] Mt.Vesuvius
4] Cotopaxi
Answer : [ 4 ]

Question. Which of the following is not caused by endogenic forces -
1] Glaciers
2] Landslides
3] Volcanic eruptions
4] Earthquake
Answer : [ 1 ]

Question. The place of origin of an earthquake is called-
1] Vent
2] Zone
3] Focus
4] Epicentre
Answer : [ 3 ]

Question. Which of the following is an extinct volcano –
1] Stromboli
2] Mt. Aconcagua
3] Mt.Vesuvius
4] Mt.Kea
Answer : [ 2 ]

 FILL IN THE BLANKS :

Question. Active Valcanoes are also called………………
Answer : Live volcanoes

Question. The conical……….is formed when the erupted materials collect around the vent .
Answer : mountain

Question. The intensity of the earthquake is maximum near the ……………..
Answer : epicentre

Question. The magnitude of earthquake waves is measured on the …………scale.
Answer : Richter 

Question. The forces which originate from within the earth are called…………forces .
Answer : endogenic

VERY SHORT QUESTION ANSWERS :

Question. What is the theory of Continental Drift ?
Answer : Theory of continental drift suggested, that millions of years ago ,all Landmasses were joined together into a supercontinent , called the Pangaea.

Question. What do you mean by epicentre ?
Answer : The point on the earth’s surface ,which is vertically above the focus. The intensity of an earthquake is maximum near the epicentre.

Question. Define Seismograph ?
Answer : An instrument that detects , measures and records an earthquake Is called seismograph.

Question. What are the three major earthquake zones ?
Answer : The Earth has three major earthquake zones. The first large area kn- own as the Pacific Ring of Fire. The second major earthquake zone is along the mid-Ocean ridges.The third major earthquake zone is the Eurasian-Melanesian Mountain belt .

Question. What are the two types of Earthquake waves ?
Answer : There are two types of earthquake waves , Body Waves- which travel through the interior of the earth . Surface Waves arrive and travel on the earth’s surface starting from the epicentre.

SHORT QUESTION ANSWERS :

Question. Explain the concept of Plate Tectonic ?
Answer : Plate tectonics explains the features and movements of earth sur- face , from deepest ocean trench to the tallest mountain. The earth’s crust consists of lithosphere. There are several major and minor plates, all float independently . The rate of movement of the plates is extrem- ely slow , about a few millimetres per year . Tectonic activities such as earthquakes and volcanicity , occur along the plate margins. The plates are in a constant motion.

Question. What do we understand by Richter scale ?
Answer : The magnitude of an earthquake is measured on the Richter Scale. The Richter Scale ranges from zero to nine. An increase in one point on the Richter scale indicates that the force of the earthquake is 10 time greater than the strength of the previous number. The Richter Scale is used to rate the amount of energy released during an earth- quake.

LONG QUESTION ANSWER :

Question. Describe a Volcano, explain its various parts with the help of diagram?
Answer : A Volcano is a vent or opening in the earth’s crust through which molten material erupts suddenly. Magma and other volcanic materials are chann- eled to the surface where they expelled through a crack or hole. The three main parts of a volcano are the chamber ,vent ,and the crater. Way below the surface of the earth is the crust, where volcanic activity begins . Mag- ma is contained in magma chamber. A space within the earth that holds the hot melted rock. Magma also contains gasses, that start to build up pressure over times. When the pressure becomes extreme,the magma is pushed out of the earth through main vent, somewhat like pipeline. The magma shoots through this pipeline in order to escape the earth. A crater is formed when the volcano literally blows its top ,pushing out anything on the earth’s surface, e.g. the Deccan Plateau in India.

Choose the correct answer:

1. The earth’s crust consists of several large and small plates which carry continents and the ocean floor, known as ________________.

a. Exogenic forces

b. Lithospheric plates

c. Mantle

2. The forces that act in the interior of the earth are called_________________.

a. Endogenic forces

b. Exogenic forces

3. The forces that work on the surface of the earth are called _______________.

a. Endogenic forces

b. Exogenic forces

4. The place in the crust where the movement starts is called the _____________.

a. Focus

b. Epicentre

c. Magma chamber

5. The place on the surface above the focus is called the _______________ .

a. Focus

b. Epicentre

c. Crater

6. When the river enters the plain it twists and turns forming large bends known as _____________ .

a. Ox-bow lake

b. Levees

c. Meanders

7. Crescent shaped lake formed by meandering river is known as ____________.

a. Ox-bow lake

b. Levees

c. Meanders

8. Near the sea the river begins to breakup into a number of streams called_______.

a. Tributaries

b. Distributaries

Fill in the blanks:

9. The Lithospheric plates move because of the movement of ________________ inside the earth.

10. Because of the sudden forces, movements like ____________ and _________ takes place.

11. A ____________ is a vent in the earth’s crust through which molten material erupts suddenly.

Please refer to attached file for CBSE Class 7 Geography Worksheets (10) - Our Changing Earth