Internal Structure of the Earth | World Physical Geography | Geomorphology| Dr. Krishnanand

Summary

This video provides a detailed exploration of Earth's internal structure, focusing on its core layers—outer and inner core. The outer core, composed of iron and nickel, is in a liquid state, while the inner core is solid and extremely dense. Key concepts like the dynamo theory, which explains Earth's magnetic field, are covered. The video also delves into seismic wave behavior and key discontinuities within Earth's layers, such as the Moho and Gutenberg discontinuities. With temperature and pressure changes playing a crucial role, this video offers a comprehensive understanding of Earth's composition and dynamics.

Takeaways

• 😀 The Earth's outer core lies between 2,900 and 5,100 km beneath the surface, composed mostly of iron and nickel, and remains in a liquid state due to insufficient pressure.
• 😀 The outer core's temperature ranges from 4,400°C to 6,000°C, with a density between 9.9 to 12.2 grams per cubic centimeter.
• 😀 Earth's magnetic field is generated by convection currents in the liquid outer core, following the dynamo theory, which combines convection with the Coriolis effect.
• 😀 The inner core, extending from the Earth's center to 5,100 km, is mostly composed of 80% iron and some nickel, and is solid due to extreme pressure despite its high temperature.
• 😀 The density of the inner core ranges from 12.6 to 13 grams per cubic centimeter, and it cannot sustain a permanent magnetic field.
• 😀 Earth's core contributes only 16% of Earth's volume but accounts for 33% of its mass, indicating the significant density of the core materials.
• 😀 The **Moho discontinuity** marks the boundary between the oceanic and continental crusts, indicating a change in composition and material.
• 😀 The **Lehmann discontinuity** marks the boundary between the outer and inner core, as discovered by scientist Lee Mann.
• 😀 The **Gutenberg discontinuity** lies between the lower mantle and the outer core, signaling a transition in Earth's material composition.
• 😀 The oceanic crust is thinner than the continental crust, and the lower portion of the mantle is incorrectly referred to as the asthenosphere (it is the upper portion).

Q & A

What is the composition of the Earth's outer core?

The Earth's outer core is composed mainly of iron and nickel, with trace amounts of lighter elements.

Why is the outer core in a liquid state?

The outer core is in a liquid state because it is not under enough pressure to become solid.

What is the density range of the Earth's outer core?

The density of the Earth's outer core ranges from 9.9 to 12.2 grams per cubic centimeter.

What is the temperature range of the outer core?

The temperature of the Earth's outer core ranges from 4400°C to 6000°C.

What is the dynamo theory and how is it related to Earth's magnetic field?

The dynamo theory suggests that convection in the outer core, combined with the Coriolis effect, generates the Earth's magnetic field.

What is the primary composition of the Earth's inner core?

The Earth's inner core is primarily composed of 80% iron, with additional nickel and ferrous materials.

What is the temperature near the center of the Earth?

The temperature near the center of the Earth is approximately 6000°C, which is 1000°C hotter than previously thought.

What are discontinuities in the Earth's structure?

Discontinuities are boundaries between layers of the Earth where there is a change in composition or physical state, such as between the crust and mantle or between the outer and inner core.

What is the Moho discontinuity and how was it discovered?

The Moho discontinuity is the boundary between the lithosphere and asthenosphere, and it was discovered during the Yugoslavian earthquake in the 1940s.

What is the correct statement about the Earth's crust compared to the mantle?

The oceanic crust is thinner than the continental crust, as per the comparison between the two types of crust.