If you are a student of class 7th and searching for Model Activity Task Class 7 Geography Part 3, then we are here to help you. In this article, we have prepared all questions and answers carefully.
Chapter 3 Our Changing Earth
Our Changing Earth” explains plate tectonics, the movement of Earth’s plates, causing earthquakes, volcanoes, and mountains. Erosion and weathering shape the surface, while glaciers, rivers, and waves contribute to landform changes. All questions and Answers are given below
Model Activity Task Class 7 Geography Part 3
Answer the following questions
Q No:1 Why do the plates move?
Answer: The Earth’s plates move because of a process called plate tectonics. The outer layer of the Earth, known as the lithosphere, is divided into large plates. These plates float on the semi-fluid layer beneath, called the asthenosphere. The movement of these plates is driven by convection currents in the asthenosphere, caused by heat from the Earth’s interior. This movement leads to various geological events such as earthquakes, volcanic eruptions, and the formation of mountains.
Q No:2 What are exogenic and endogenic forces?
Answer: Exogenic forces are external processes like erosion and weathering that shape the Earth’s surface. Endogenic forces are internal processes caused by plate movements, volcanoes, and mountains forming.
Q No:3 What is erosion?
Erosion is the process of wearing away and transporting soil, rocks, or other materials from one location to another. It is primarily caused by natural elements such as wind, water, ice, and gravity. These forces act on the Earth’s surface, gradually removing and carrying away particles or fragments of land, altering the landscape over time. Erosion plays a significant role in shaping valleys, canyons, coastlines, and other geological features.
Q No:4 How are flood plains formed?
Answer: Flood plains are formed through a natural process involving the deposition of sediment by flowing water during periods of flooding. When a river overflows its banks during a flood, it carries a significant amount of sediment, such as sand, silt, and clay. As the water slows down on the floodplain, it loses its energy and deposits the sediment it was carrying. Over time, repeated flooding events result in layer upon layer of sediment being deposited on the floodplain.
Q No:5 What are sand dunes?
Answer: Sand dunes are hills of sand found in deserts or coastal areas. They are created by the wind blowing and depositing sand grains. The shape and size of dunes vary depending on wind patterns and available sand. Sand dunes play an important role in stabilizing desert ecosystems and protecting coastal areas from erosion.
Q No: 6 How are beaches formed?
Answer: Beaches are formed through the accumulation of sediment, such as sand or pebbles, along the shoreline. This sediment is often brought in by waves and currents from nearby sources, like rivers or eroding coastal cliffs. Over time, the repeated action of waves depositing and shaping the sediment creates the characteristic sandy or pebbly beach.
Q No: 7 What are oxbow lakes?
Answer: Oxbow lakes are U-shaped bodies of water that form when a meandering river takes a new, shorter path, leaving behind a curved, isolated section of the old river channel. Over time, the abandoned meander loop becomes cut off from the main river flow, and it fills with water, forming an oxbow lake. These lakes are named after their distinctive curved shape, resembling the yoke used on oxen.
Tick the correct answer
(i) Which is not an erosional feature of sea waves?
(c) Sea cave
Answer: (b) Beach
(ii) The depositional feature of a glacier is?
(a) Flood plain
Answer: (c) Moraine
(iii) Which is caused by the sudden movements of the earth?
(c) Flood plain
Answer: (a) Volcano
(iv) Mushroom rocks are found in?
(b) River valleys
Answer: (a) Deserts
(v) Oxbow lakes are found in?
(b) River valleys
Answer: (b) River valleys
Match the following
(i) Glacier (c) River of ice
(ii) Meanders (d) Rivers
(iii) Beach (a) Sea shore
(iv) Sand dunes (h) Deserts
(v) Waterfall (g) Hard bed rock
(vi) Earthquake (e) Vibrations of earth
Give reasons to the following questions
(i) Some rocks have a shape of a mushroom.
Reason: The rocks have a shape of a mushroom due to the process of erosion. Over time, softer rock layers beneath a harder rock cap erode at a faster rate, resulting in a distinctive mushroom-like shape.
(ii)Flood plains are very fertile?
Reason: Flood plains are fertile because periodic flooding deposits nutrient-rich sediments, enhancing soil fertility and supporting abundant plant growth.
(iii) Sea caves are turned into stacks?
Reason: Sea caves are turned into stacks through coastal erosion. The relentless action of waves gradually erodes and weakens the rock, causing the roof of the sea cave to collapse, leaving behind a tall column of rock known as a stack.
(iv) Buildings collapse due to earthquakes?
Reason: Buildings collapse during earthquakes due to the intense shaking and ground motion caused by the release of seismic energy. This shaking puts stress on the structural integrity of buildings, leading to structural failure and collapse.
In conclusion, all the answers have been prepared by our expert teachers who are teaching Geography for the class 7th Grade. Model activity task class 7 Geography part 3 is very useful for the Grade 7 students who are willing to score well in Geography.