Passage Based Questions: Interior of the Earth | Geography Class 11 - Humanities/Arts PDF Download

Passage - 1

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The most easily available solid earth material is surface rock or the rocks we get from mining areas. Gold mines in South Africa are as deep as 3 - 4 km. Going beyond this depth is not possible as it is very hot at this depth. Besides mining, scientists have taken up a number of projects to penetrate deeper depths to explore the conditions in the crustal portions. Scientists world over are working on two major projects such as “Deep Ocean Drilling Project” and “Integrated Ocean Drilling Project”. The deepest drill at Kola, in Arctic Ocean, has so far reached a depth of 12 km.

Q1: What is the most easily available solid earth material, and where is it commonly obtained?
Ans: The most easily available solid earth material is surface rock, which is obtained from mining areas.

Q2: Why is it not possible to go beyond a certain depth in gold mines, as mentioned in the passage?
Ans: Gold mines in South Africa reach depths of 3 - 4 km, and it is not possible to go deeper because of the intense heat at such depths, making it inhospitable for human exploration.

Q3: Apart from mining, what are the two major projects undertaken by scientists to explore deeper depths of the Earth, as mentioned in the passage?
Ans:

• Scientists are working on two major projects: the "Deep Ocean Drilling Project" and the "Integrated Ocean Drilling Project" to explore the conditions in the crustal portions of the Earth.
• Additionally, the Kola drill in the Arctic Ocean has reached a depth of 12 km, indicating significant progress in drilling into the Earth's crust.

Passage - 2

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Another source of information are the meteors that at times reach the earth. However, it may be noted that the material that becomes available for analysis from meteors, is not from the interior of the earth. The material and the structure observed in the meteors are similar to that of the earth. They are solid bodies developed out of materials same as, or similar to, our planet. Hence, this becomes yet another source of information about the interior of the earth.

Q1: What is another source of information about the Earth's interior, apart from mining and drilling, as mentioned in the passage?
Ans: Meteors that reach the Earth serve as another source of information about the Earth's interior.

Q2: How is the material from meteors similar to the Earth's interior, as per the passage?
Ans:

• The material and structure observed in meteors are similar to that of the Earth.
• Meteors are solid bodies developed out of materials that are the same as, or similar to, our planet, making them valuable sources of information about the Earth's interior.

Passage - 3

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The reading of the gravity at different places is influenced by many other factors. These readings differ from the expected values. Such a difference is called gravity anomaly. Gravity anomalies give us information about the distribution of mass of the material in the crust of the earth. Magnetic surveys also provide information about the distribution of magnetic materials in the crustal portion, and thus, provide information about the distribution of materials in this part. Seismic activity is one of the most important sources of information about the interior of the earth. Hence, we shall discuss it in some detail.

Q1: What is meant by "gravity anomaly," as mentioned in the passage?
Ans:

• Gravity anomaly refers to the difference between the expected gravity readings and the actual gravity readings at different places.
• These anomalies provide valuable information about the distribution of mass in the Earth's crust.

Q2: Besides gravity anomalies, what other methods are used to study the distribution of materials in the Earth's crust, as stated in the passage?
Ans:

• Magnetic surveys are used to study the distribution of magnetic materials in the Earth's crust, providing information about material distribution.
• Seismic activity is another crucial source of information about the Earth's interior and is discussed in detail in the passage.

Q3: Why is seismic activity considered one of the most important sources of information about the Earth's interior, according to the passage?
Ans:

• Seismic activity provides valuable information about the Earth's interior.
• It helps scientists understand the composition and structure of the Earth's layers, making it one of the most important sources of information about the Earth's interior.

Passage - 4

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There are two types of body waves. They are called P and S-waves. P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves’. The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials. S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials. This characteristic of the S-waves is quite important. It has helped scientists to understand the structure of the interior of the earth. Reflection causes waves to rebound whereas refraction makes waves move in different directions.

Q1: What are the two types of body waves, and what are they called?
Ans:

• The two types of body waves are P-waves and S-waves.
• P-waves are also known as primary waves, while S-waves are referred to as secondary waves.

Q2: How do P-waves and S-waves differ in terms of their ability to travel through different materials?
Ans:

• P-waves move faster and are the first to arrive at the surface. They can travel through gaseous, liquid, and solid materials.
• S-waves arrive at the surface with some time lag and can only travel through solid materials, not through liquids or gases.

Q3: How do reflection and refraction affect seismic waves, as mentioned in the passage?
Ans:

• Reflection causes waves to rebound, altering their direction after striking a surface.
• Refraction makes waves move in different directions, changing the path of the waves through the materials they travel in.
• These phenomena are crucial in understanding how seismic waves behave and how they provide insights into the Earth's interior structure.

Passage - 5

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The earthquake events are scaled either according to the magnitude or intensity of the shock. The magnitude scale is known as the Richter scale. The magnitude relates to the energy released during the quake. The magnitude is expressed in numbers, 0-10. The intensity scale is named after Mercalli, an Italian seismologist. The intensity scale takes into account the visible damage caused by the event. The range of intensity scale is from 1-12. 

Q1: How are earthquake events scaled, and what does the Richter scale measure?
Ans:

• Earthquake events are scaled based on either magnitude or intensity of the shock.
• The magnitude scale, known as the Richter scale, measures the energy released during the earthquake.
• Magnitude values are expressed on a scale from 0 to 10, reflecting the seismic energy released.

Q2: What is the intensity scale named after, and what does it consider in its measurements?
Ans:

• The intensity scale is named after Mercalli, an Italian seismologist.
• The Mercalli intensity scale takes into account the visible damage caused by the earthquake event, providing a measure of its impact on the affected area.
• Intensity values on this scale range from 1 to 12, with higher numbers indicating greater observed damage and impact.

Passage - 6

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The first six listed above have some bearings upon landforms, while others may be considered the effects causing immediate concern to the life and properties of people in the region. The effect of tsunami would occur only if the epicentre of the tremor is below oceanic waters and the magnitude is sufficiently high. Tsunamis are waves generated by the tremors and not an earthquake in itself. Though the actual quake activity lasts for a few seconds, its effects are devastating provided the magnitude of the quake is more than 5 on the Richter scale.

Q1: What are tsunamis, and how are they generated?
Ans:

• Tsunamis are waves generated by tremors (earthquakes) occurring below oceanic waters, not earthquakes themselves.
• Tsunamis occur if the epicenter of the earthquake is below the oceanic waters and the earthquake's magnitude is sufficiently high.

Q2: How do the effects of an earthquake relate to its magnitude, as mentioned in the passage?
Ans:

• The effects of an earthquake are devastating if its magnitude is more than 5 on the Richter scale.
• Even though the actual earthquake activity lasts only for a few seconds, the impact can be severe, especially if the magnitude is significant.

Q3: What determines whether the effect of a tsunami would occur, as per the passage?
Ans:

• The effect of a tsunami occurs only if the epicenter of the earthquake is below oceanic waters and the earthquake's magnitude is sufficiently high.
• Tsunamis are specifically waves generated by tremors occurring under the ocean and can have catastrophic effects if certain conditions, including magnitude, are met.

Passage - 7

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These volcanoes are characterised by eruptions of cooler and more viscous lavas than basalt. These volcanoes often result in explosive eruptions. Along with lava, large quantities of pyroclastic material and ashes find their way to the ground. This material accumulates in the vicinity of the vent openings leading to formation of layers, and this makes the mounts appear as composite volcanoes.

Q1: How are the eruptions of these volcanoes characterized in terms of lava, and what type of eruptions do they often result in?
Ans:

• These volcanoes are characterized by eruptions of cooler and more viscous lavas than basalt.
• They often result in explosive eruptions.

Q2: What type of materials, in addition to lava, are typically ejected during the eruptions of these volcanoes, as mentioned in the passage?
Ans: In addition to lava, these volcanoes eject large quantities of pyroclastic material and ashes during their eruptions.

Q3: How does the accumulation of pyroclastic material and ashes near vent openings contribute to the appearance of these volcanoes?
Ans:

• The accumulation of pyroclastic material and ashes in the vicinity of the vent openings leads to the formation of layers.
• This layering effect makes the volcanic mounts appear as composite volcanoes, which are characterized by their stratified structure.

Passage - 8

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The lava that is released during volcanic eruptions on cooling develops into igneous rocks. The cooling may take place either on reaching the surface or also while the lava is still in the crustal portion. Depending on the location of the cooling of the lava, igneous rocks are classified as volcanic rocks (cooling at the surface) and plutonic rocks (cooling in the crust). The lava that cools within the crustal portions assumes different forms. These forms are called intrusive forms.

Q1: What does lava develop into upon cooling during volcanic eruptions, and under what conditions can this cooling occur?
Ans:

• Lava released during volcanic eruptions develops into igneous rocks upon cooling.
• The cooling can take place either on reaching the surface or while the lava is still within the crustal portion of the Earth.

Q2: How are igneous rocks classified based on the location of lava cooling, and what are the two main types mentioned in the passage?
Ans: Igneous rocks are classified as volcanic rocks (cooling at the surface) and plutonic rocks (cooling in the crust) based on the location of lava cooling.

Q3: What term is used to describe the different forms assumed by lava cooling within the crustal portions, as mentioned in the passage?
Ans:

• The different forms assumed by lava cooling within the crustal portions are called intrusive forms.
• These intrusive forms refer to the various shapes and structures formed by lava as it cools and solidifies beneath the Earth's surface.

Passage - 9

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These are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. It resembles the surface volcanic domes of composite volcano, only these are located at deeper depths. It can be regarded as the localised source of lava that finds its way to the surface. The Karnataka plateau is spotted with domal hills of granite rocks.

Q1: What are these large dome-shaped intrusive bodies called, and how are they connected to the Earth's surface?
Ans:

• These large dome-shaped intrusive bodies are called batholiths.
• They are connected to the Earth's surface by a pipe-like conduit from below.

Q2: How do batholiths resemble surface volcanic domes, and where are they located in comparison to these surface domes?
Ans: Batholiths resemble surface volcanic domes of composite volcanoes but are located at deeper depths within the Earth's crust.

Q3: Can you provide an example of a region with such dome-shaped intrusive bodies, as mentioned in the passage?
Ans: Yes, the passage mentions that the Karnataka plateau is spotted with domal hills of granite rocks, indicating the presence of these dome-shaped intrusive bodies in that region.