Quick Review Flashcards - Click to flip and test your knowledge!
Question
From which primary source do scientists obtain knowledge about the Earth's interior instead of direct excavation?
Answer
The study of seismic waves.
Question
Which type of earthquake waves are able to reach the surface of the Earth?
Answer
Primary waves ($P$-waves).
Question
Why are secondary waves ($S$-waves) unable to pass through the Earth's outer core?
Answer
Secondary waves cannot pass through liquids.
Question
What specific site deep inside the Earth serves as the source for molten material thrown up by volcanoes?
Answer
The magma chamber.
Question
Why do scientists study meteorites to understand the Earth's interior?
Answer
The Earth is believed to be constituted of the same materials as meteorites.
Question
What is the primary source of the heat given out by the Earth's interior?
Answer
Radioactive elements deep inside the Earth.
Question
What term describes the blanket of gases that envelopes the Earth?
Answer
Atmosphere.
Question
The parts of the Earth's crust immersed under oceans and seas form the _____.
Answer
Hydrosphere.
Question
Which of the Earth's concentric layers is the thinnest?
Answer
The Lithosphere (or crust).
Question
Name three common types of minerals found in the rocks of the Lithosphere.
Answer
Silicates, feldspar, and mica.
Question
What are the two broad chemical divisions of the Lithosphere?
Answer
SIAL and SIMA.
Question
Why does the Sial layer appear to float above the Sima layer?
Answer
Sial has less density than Sima.
Question
Which two chemical elements give the 'Sial' layer its name?
Answer
Silica ($Si$) and Aluminium ($Al$).
Question
The name 'Sima' is derived from which two chemical elements?
Answer
Silica ($Si$) and Magnesium ($Mg$).
Question
Which layer of the Earth's crust forms the continents?
Answer
The Sial layer.
Question
Which layer of the Earth's crust makes up the ocean floor?
Answer
The Sima layer.
Question
What is the collective name given to the core of the Earth based on its chemical composition?
Answer
NIFE.
Question
Which two heavy metals primarily compose the Earth's core?
Answer
Nickel ($Ni$) and Iron ($Fe$).
Question
Why are heavy metals like Nickel and Iron found deep inside the Earth rather than on the surface?
Answer
They have high density.
Question
According to chemical composition, what are the three main layers of the Earth's interior?
Answer
Core, Mantle, and Crust.
Question
Which part of the Earth is considered the most inaccessible and lies at the centre?
Answer
The core.
Question
Which of the Earth's layers is the densest?
Answer
The core.
Question
What is the approximate total diameter of the Earth's core?
Answer
$7000\text{ km}$.
Question
What is the estimated temperature range of the Earth's core?
Answer
$4400^{\circ}C$ to $6000^{\circ}C$.
Question
Which layer of the Earth is responsible for its magnetism?
Answer
The core.
Question
What evidence suggests that the Earth's outer core is in a molten state?
Answer
Secondary waves ($S$-waves) disappear in the outer core.
Question
Why is the inner core of the Earth in a solid state despite the extreme heat?
Answer
High density and pressure have compressed the molten material.
Question
Which layer of the Earth lies directly below the crust?
Answer
The mantle.
Question
What is the average thickness of the Earth's mantle?
Answer
$2900\text{ km}$.
Question
What percentage of the Earth's total volume is made up by the mantle?
Answer
$84$ per cent.
Question
What are the two subdivisions of the Earth's mantle?
Answer
The upper mantle and the lower mantle.
Question
The upper mantle extends from the Moho Discontinuity to a depth of _____.
Answer
$700\text{ km}$.
Question
How does the lower mantle compare to the upper mantle in terms of density and heat?
Answer
The lower mantle is hotter and denser.
Question
At what depth range is the partially molten layer known as the asthenosphere found?
Answer
$100$ to $410\text{ km}$.
Question
Term: Asthenosphere
Answer
Definition: A partially molten layer of the mantle found at depths of $100$ to $410\text{ km}$.
Question
Why is the lower mantle solid despite its high temperature?
Answer
High pressure keeps the rocks in a solid state.
Question
As pressure increases towards the Earth's interior, what happens to the density of the materials?
Answer
The density increases.
Question
What is the range of temperature variation within the Earth's mantle?
Answer
$1000^{\circ}C$ to $3700^{\circ}C$.
Question
What is the name of the boundary interface between the mantle and the core?
Answer
The Gutenberg Discontinuity.
Question
At what approximate depth does the Gutenberg Discontinuity begin?
Answer
$2800\text{ km}$.
Question
What happens to the velocity of primary seismic waves at the Gutenberg Discontinuity?
Answer
Their velocity decreases.
Question
The term 'Lithosphere' is derived from the Greek word 'Lithos', which means _____.
Answer
Stones or rocks.
Question
What percentage of the Earth's total mass is accounted for by the crust?
Answer
$1$ per cent.
Question
What is the thickness of the Earth's crust below high mountains?
Answer
$60\text{ km}$.
Question
What is the thickness of the Earth's crust below the oceans?
Answer
$5$ to $10\text{ km}$.
Question
What is the estimated temperature of the upper part of the oceanic crust?
Answer
$0^{\circ}C$.
Question
What is the name of the boundary that separates the Earth's crust from the mantle?
Answer
The Mohorovicic Discontinuity (Moho Discontinuity).
Question
Who discovered the Moho Discontinuity in 1909?
Answer
Andreaja Mohorovicic.
Question
At what depth is the Moho Discontinuity typically found beneath the oceans?
Answer
$8\text{ km}$.
Question
At what depth is the Moho Discontinuity typically found beneath the continents?
Answer
$32\text{ km}$.
Question
Which boundary layer possesses the characteristics of both the crust and the mantle?
Answer
The Moho Discontinuity.
Question
Which theory put forward by Wegener in the early 20th century suggests the crust undergoes structural changes?
Answer
The Theory of Continental Drift.
Question
Which theory from the 1960s suggests that lateral movements of plates give the Earth a new shape?
Answer
The Theory of Plate Tectonics.
Question
In the analogy 'Continents : SIAL', what is the corresponding pair for SIMA?
Answer
Ocean floor.
Question
What is the correct order of Earth's layers when moving from the centre toward the surface?
Answer
Core - Mantle - Crust.
Question
How does the pressure of rocks change as depth into the Earth increases?
Answer
Pressure increases with depth.
Question
What happens to the $S$-waves when they reach the Gutenberg Discontinuity?
Answer
They disappear completely.
Question
Why is the Earth's interior primarily in a solid state despite high temperatures?
Answer
High pressure prevents melting in most areas.
Question
Which part of the Earth's interior is described as the 'NIFE' layer?
Answer
The core.
Question
Identify the transitional zone where seismic waves show an abrupt change at a depth of $2800\text{ km}$.
Answer
Gutenberg Discontinuity.