Layers of the Earth

Question 1

What do you understand by the term ‘chemical composition’?

Answer 1

Refers to the specific elements and compounds that make up each specific layer of the Earth. The Earth is divided into different layers based on chemical composition.

Question 2

What do you understand by the term ‘physical properties’?

Answer 2

Refers to the observable and measurable characteristics of each layer that define their behavior and interactions. eg. Strength and rigidity

Question 3

What comes under the Chemical Composition of the Earth?

Answer 3

• Crust
• Mantle
• Core

Question 4

What comes under the Physical Properties of the Earth?

Answer 4

• Lithosphere
• Asthenosphere
• Mesosphere
• Inner Core
• Outer Core

Question 5

What is the crust?

Answer 5

• Rocky and Brittle Outer Layer of the Earth
• 0-45 km
• Has 2 parts:
  . Continental Crust: Thicker and primarily made up of granite (30-50km)
  . Oceanic Crust: Thinner but denser, primarily made up of basalt (0-7 km)
• Major constituent element is SIAL (Silica and Aliminium)
• 1% of Earth’s volume and 0.5% of Earth’s crust

Question 6

What is the mantle?

Answer 6

• Solid layer or rock that lies below the mantle and above the core
• 84% of Earth’s volume and 67% of Earth’s mass
• Has 2 parts:
  . Upper Mantle- hard, solid rock
  . Lower Mantle- hot, soft rock
• Major constituent is SIMA (Silica and Magnesium)

Question 7

What is the core?

Answer 7

• Innermost, hot dense layer surrounding the core
• 15% of Earth’s volume and 32.5% of Earth’s mass
• Has 2 parts:
  . Inner Core- Solid
  . Outer Core- Liquid / Semi-liquid
• Major constituent is NIFE (Nickel and Iron (Ferrous))

Question 8

What is the Barysphere

Answer 8

The barysphere is used to refer to the Earth’s core and sometimes the whole interior

Question 9

What is the discontinuity between the Crust and the Hydrosphere?

Answer 9

Conrad Discontinuity

Question 10

What is the discontinuity between the Crust and the Mantle?

Answer 10

Mohorovicic Discontinuity

Question 11

What is the discontinuity between the Upper and the Lower Mantle?

Answer 11

Repetti Discontinuity

Question 12

What is the discontinuity between the Inner and Outer Core?

Answer 12

Lehmaan Discontinuity

Question 13

What is the Lithosphere?

Answer 13

• Solid, rigid outer layer of the Earth
• Comprises of the Crust and the Upper Mantle
• Sometimes called the SIAL

Question 14

What is the Asthenosphere?

Answer 14

• Highly viscous, mechanically weak and ductile deformed upper region of the mantle below the Lithosphere
• 80-200 km
• Main Source of Magma
• Layer over which Lithospheric plates/Continental Plates move

Question 15

What is the Mesosphere?

Answer 15

• Rigid lower part of the mantle
• Portion of the Mantle which is below the lithosphere and the asthenosphere but above the crust

Question 16

Differentiate between crust, mantle and core

Answer 16

Crust- SIAL
Mantle- SIMA
Core- NIFE
2. Density: The mass per unit volume of the materials in each layer.
o Crust: Less dense compared to the mantle and core
o Mantle: Denser than the crust
o Core: Densest part of the Earth

Question 17

Define SIAL

Answer 17

SIAL: An acronym for Silica-Aluminum. Refers to the upper part of the Earth’s crust, which is rich in silicon (Si) and aluminum (Al). This layer includes the continental crust and is characterized by a lower density compared to the underlying mantle. It is composed primarily of rocks like granite.

Question 17

Why is it important to divide the layers of the Earth based on chemical composition and physical properties?

Answer 17

Understanding Earth’s Structure: It helps scientists comprehend the Earth’s internal structure and the distinct materials that make up each layer, leading to insights into the formation and evolution of our planet.

Safety and Engineering: It informs engineering practices, such as constructing buildings and infrastructure, by providing information on the stability and composition of the ground.

Predicting Behavior: Different layers have unique physical and chemical properties that influence their behavior. For example, the solid nature of the crust affects tectonic plate movements, while the liquid outer core is crucial for generating Earth’s magnetic field.

Question 18

Define SIMA

Answer 18

SIMA: An acronym for Silica-Magnesium. Refers to the lower part of the Earth’s crust and the upper part of the mantle. This layer is rich in silicon (Si) and magnesium (Mg), and it is more dense than the SIAL layer. It includes the oceanic crust and is composed mainly of basaltic rocks.

Question 19

Define NIFE

Answer 19

An acronym for Nickel-Iron. Refers to the Earth’s core, which is primarily composed of nickel (Ni) and iron (Fe). The core is divided into a liquid outer core and a solid inner core. This composition is responsible for generating Earth’s magnetic field and contributes to the core’s high density.