Plate Tectonics Important Questions

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Very Short Answers Questions [1 Mark Questions]

Ques. The theory of plate tectonics was widely accepted by

1. about 1960
2. about 1950
3. the end of the 19th century
4. about 1970

Ans. The correct answer is d. about 1970

Explanation: The theory of plate tectonics, which explains how the Earth's surface is constantly changing due to the movement of tectonic plates, was not widely accepted until the 1970s.

Ques. Approximately how many lithospheric plates are there?

1. about 15
2. about 3
3. about 24
4. about 6

Ans. The correct answer is a. about 15

Explanation: The Earth's lithosphere is made up of about 15 major and numerous minor tectonic plates. These plates are constantly moving and interacting with each other, which causes a variety of geological phenomena, such as earthquakes, volcanic eruptions, and mountain building.

Ques. The eruption of magma onto the surface is referred to as

1. Lightning
2. Earthquake
3. Thunder
4. Volcanism

Ans. The correct answer is d. Volcanism

Explanation: Volcanism is the process of molten rock (magma) erupting onto the surface of a planet.

Ques. The relative movement of the plates ranges from _______ annually.

1. 0 to 100 mm
2. 0 to 10 mm
3. 10 to 1000 mm
4. 0 to 1 mm

Ans. The correct answer is a. 0 to 100 mm

Explanation: The relative movement of tectonic plates ranges from 0 to 100 millimeters annually.

Ques. The Earth’s mantle zone lying beneath the lithosphere is known as

1. Biosphere
2. Asthenosphere
3. Atmosphere
4. Hydrosphere

Ans. The correct answer is b. Asthenosphere

Explanation: The asthenosphere extends from approximately 100 km to about 700 km below the surface of the Earth.

Ques. There are no dynamic tectonic plates found in the earth’s crust.

1. True
2. False

Ans. The correct answer is b. False

Explanation: The Earth's crust is made up of several large, dynamic tectonic plates that are constantly moving and interacting with each other. These plates are the outermost layer of the Earth's lithosphere, which is the rigid outermost layer of the planet.

Ques. Plate tectonics results in

1. Earthquake
2. Mountain-building
3. Volcanism
4. All of the above

Ans. The correct answer is d. All of the above

Explanation: Plate tectonics is responsible for earthquakes, mountain formation, and volcanism.

Ques. ______ happens when both plates move apart from one other.

1. Transform boundaries
2. Plate boundary zones
3. Convergent boundaries
4. Divergent boundaries

Ans. The correct answer is d. Divergent boundaries

Explanation: Divergent boundaries occur when two plates move away from one another.

Ques. The primary mechanism by which mountains are formed on continents is known as

1. Orogeny
2. Thunder
3. Volcanism
4. Earthquake

Ans. The correct answer is a. Orogeny

Explanation: The geological process that creates mountains is known as orogeny. It is the process of deformation and uplift of the Earth's crust that results in the formation of new crustal material by thickening the crust. The collision of tectonic plates causes orogeny, which causes the Earth's crust to crumple and buckle, resulting in the formation of mountains.

Ques. At what type of plate boundary do shallow-focus earthquakes occur?

1. Transform
2. Divergent
3. Convergent
4. All of the above

Ans. The correct answer is d. All of the above

Explanation: Shallow-focus earthquakes can occur at all three types of plate boundaries: divergent, convergent, and transform.

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Short Answers Questions [2 Marks Questions]

Ques. What is plate tectonics?

Ans. Plate tectonics is the scientific theory that the Earth's lithosphere is made up of a number of huge tectonic plates that have been slowly moving for around 3.4 billion years.

Ques. How many tectonic plates are there?

Ans. There are seven major tectonic plates. These include the following plates:

• African
• Antarctic
• Eurasian
• Indo-Australian
• North American
• Pacific
• South American.

Ques. What are the two types of lithosphere?

Ans. The two types of lithosphere are

• Oceanic
• Continental

Ques. Does the oceanic trench formation take place at plate boundaries?

Ans. Yes, oceanic trench formation takes place at plate boundaries. Specifically, they occur at convergent plate boundaries, where two tectonic plates collide and one is forced beneath the other. This process is called subduction.

Ques. What is orogeny?

Ans. Orogeny is the process of mountain formation that occurs near a convergent plate margin when plate motion compresses the margin. As the compressive plate crumples and is raised, an orogenic belt or orogen forms, forming one or more mountain ranges.

Ques. What is lithosphere?

Ans. A lithosphere is a rocky shell that surrounds a terrestrial planet or natural satellite. It is made up of the crust and the lithospheric mantle, which is the highest layer of the upper mantle and acts elastically over time scales of thousands of years or more.

Ques. Define the asthenosphere.

Ans. The asthenosphere is the upper mantle's mechanically weak and ductile zone. It is located in the lithosphere, between 80 and 200 km (50 and 120 mi) below the surface, and extends as far as 700 km (430 mi).

Ques. Describe where the tectonic plates are located.

Ans. The lithosphere is the planet's outermost structure, which is Earth's structure. The lithosphere is made up of the crust and a small part of the upper mantle. The lithosphere is a layer of the Earth's surface thought to be divided into tectonic plates. These plates generally move and interact with one another and are thought to be driven by natural forces on Earth.

Ques. What is the name of the layer of the Earth that is made up of tectonic plates?

Ans. The lithosphere includes the Earth's hard and unyielding outer layer, the crust, and the topmost mantle. Tectonic plates are lithosphere divisions. The pedosphere is the uppermost component of the lithosphere that chemically reacts with the atmosphere, hydrosphere, and biosphere during the soil formation process.

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Long Answers Questions [3 Marks Questions]

Ques. What are the causes of plate tectonics?

Ans. The causes of plate tectonics are

• Earthquakes are caused by it.
• It is the source of volcanic activity.
• It increases element recycling both within the biosphere and between the geosphere and the biosphere.
• It results in the creation of mountains.

Ques. What are the impacts of tectonic plate movement?

Ans. The relative movement of tectonic plates causes tectonic processes, which are interactions between tectonic plates that affect the structure of the Earth's crust. 

• Tectonic hazards can result from tectonic processes. 
• They cause the majority of earthquakes, volcanic activity, and tsunamis. 
• Natural disasters are declared when tectonic hazards inflict major harm to societies or communities (such as loss of life, injuries, and infrastructure destruction) and they can no longer cope with their own resources.

Ques. Why was the theory of tectonic plates proposed?

Ans. When seismographs recorded the vibrations of Earthquakes in the 1960s, the theory of tectonic plates was developed. 

• Seismographs were first used to test bombs during World War II. 
• They also discovered the epicenters of the earthquakes, allowing them to locate the shape of tectonic plates. 
• Plate tectonics theory explains why the earth's geology evolves, why particular areas are prone to specific risks, and why some areas have mountain ranges.

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Very Long Answers Questions [5 Marks Questions]

Ques. What are the different types of plate boundaries?

Ans. Plate boundaries are classified into three categories

• Transform Boundaries: Transform Plate Boundaries are the points at which two plates slide past one other during transformation. The fracture zone that creates the transform plate boundary is known as a transform fault. The majority of transform faults in the ocean basin connect mid-ocean ridge offsets. Only a few of them connect mid-ocean ridges and subduction zones.

• Divergent Boundaries: A tectonic boundary is produced by magma rising to the Earth's surface between two plates as they separate, resulting in the formation of a new crust. Divergent plate boundaries can be observed in the center of the Red Sea and along the Atlantic Ocean's mid-ocean ridge.

• Convergent Boundaries: When two tectonic plates of similar density collide at a convergent boundary, they push against each other, causing the Earth's crust to buckle and rise, forming a mountain range. During this process, the edges of the plates may also melt and form new igneous rock. The uplifted mountain range can erode over time, but it will still remain a prominent feature of the landscape.

Ques. How do tectonic plates float on the mantle?

Ans. Because of the composition of the rocks within the plates, tectonic plates can float on the mantle. 

• As a result, they are less dense than the mantle. 
• The continental crust is made up of granite rock, which is composed of quartz, feldspar, and other relatively lightweight materials mostly composed of silicon and aluminum. 
• The oceanic crust is made up of basaltic rock and other components mostly composed of silicon and magnesium. 
• The oceanic crust is substantially denser yet much thinner than the continental crust. 
• The continental crust may be up to 100 km thick, whereas the oceanic crust is only approximately 5 km thick.

Ques. What would happen if plate tectonics ceased?

Ans. Earth would undergo a drastic transformation if plate motion were to cease. 

• Plate tectonics, the driving force behind mountain formation and volcanic activity, would grind to a halt, silencing the Earth's fiery breath.
• The Pacific Ring of Fire, a chain of volcanoes encircling the Pacific Ocean, would fall silent, its fiery sentinels extinguished. 
• The volcanic procession along the Hawaiian Islands would cease, leaving no trace of its fiery trail.
• Earthquakes, often triggered by plate motion, would become a rare occurrence, their tremors fading into the silence. 
• Mountains, sculpted by the relentless dance of tectonic plates, would gradually succumb to erosion's relentless assault, their towering peaks reduced to gentle slopes over millennia.
• A critical concern arises from the cessation of plate motion: the Earth's ability to release its internal heat. 
• Without the plates' continuous movement, our planet would need to devise a new and efficient mechanism to shed its fiery core.

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