30 Questions
What is the main source of magma in the Earth's interior?
Asthenosphere
Which part of the Earth is known to be brittle in nature?
Crust
What is the average thickness of the oceanic crust?
5 km
Which region has a continental crust that can be as thick as 70 km?
Himalayan region
Why is the gravitation force (g) greater near the poles compared to the equator?
The distance from the center of the earth is less at the poles than at the equator.
What is the weak zone within the mantle called?
Asthenosphere
What term is used to describe the difference between observed gravity readings and expected values?
Gravity anomaly
How do magnetic surveys help understand the distribution of materials in the crustal portion?
By providing information about magnetic materials
From where to where does the mantle extend in the Earth's interior?
Crust to 2,900 km deep
What causes an earthquake to occur according to the text?
Release of energy along a fault
Why are seismic waves crucial for understanding the interior of the earth?
They provide insights into the layered interior
How does the uneven distribution of mass within the earth influence gravity values?
It affects the gravitational force at different locations
What is the material in the upper mantle portion called before it reaches the surface?
Magma
Which of the following is NOT included in the materials that reach the ground during volcanic eruptions?
Hydrogen compounds
What is the classification basis used for categorizing volcanoes?
Nature of eruption and surface form
Which type of volcano is considered the largest on Earth, except for basalt flows?
Shield Volcanoes
At what depth is the core-mantle boundary located?
2,900 km
Which element primarily constitutes the core of the Earth?
Nickel and Iron
What is the main source of information about the earth's interior discussed in the text?
Surface rock samples from mining areas
Why is it not possible to drill beyond 3 - 4 km in gold mines in South Africa?
Because it becomes very hot at greater depths
What kind of materials have scientists analyzed to gain knowledge about the earth's interior?
Surface rock from mining areas
What are the two major drilling projects mentioned in the text for exploring the earth's crustal portions?
Deep Ocean Drilling Project and Integrated Ocean Drilling Project
What is the deepest depth reached by a drill according to the text?
12 km
Why is most of our knowledge about the earth's interior based on estimates and inferences?
Because direct observations are not possible due to extreme conditions
What type of intrusive body is a batholith?
Large dome-shaped body
How are lacoliths different from batholiths?
Lacoliths have a level base connected by a pipe-like conduit
Which of the following intrusive bodies is formed concave to the sky and is known as lapolith?
Saucer-shaped body
What is the characteristic feature of a lacolith?
Level base
Where are wavy masses of intrusive rocks sometimes found according to the text?
At the top of anticline in folded igneous country
Which type of intrusive body can be considered as the localised source of lava that finds its way to the surface?
Lacolith
Explore the distribution of earthquakes and volcanoes around the globe, and understand how they can cause damage to life and property. Learn about the structure of the Earth's crust and its variations.
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