Lesson 06.1 - Weathering and Soil: Earth's External Processes

Summary

The video explains how Earth's surface is constantly changing due to external processes like weathering, mass wasting, and erosion. These processes break down rocks, move debris downhill, and transport it via natural forces such as water and wind. Powered by the sun, external processes play a key role in the rock cycle, transforming solid rock into sediment. Unlike Earth, the moon's surface has remained largely unchanged for billions of years due to the absence of an atmosphere and hydrosphere. Internal processes, in contrast, raise land elevations through energy derived from Earth's interior.

Takeaways

• 🌍 Earth's surface is constantly changing due to the breakdown and movement of rock.
• ⛰️ Weathering starts the process by breaking down solid rock at the surface.
• ⬇️ Gravity plays a role in mass wasting, moving debris down slopes, sometimes slowly or through landslides.
• 💧 Water, wind, and glacial ice carry the disintegrated material to lower elevations.
• ☀️ The energy source for external processes like weathering and erosion comes from the sun.
• 🔄 External processes convert solid rock into sediment, contributing to the rock cycle.
• 🌕 Unlike Earth, the Moon’s surface has hardly changed for two billion years due to the absence of an atmosphere and hydrosphere.
• 💨 Without an atmosphere or hydrosphere, weathering and erosion are nearly non-existent on the Moon.
• 🏗️ External processes lower Earth's elevation, while internal processes increase it by building up the land.
• 🔥 Internal processes are powered by Earth’s interior, driven by the cooling of the planet and radioactive decay.

Q & A

What initiates the process of rock disintegration and decomposition?

Weathering starts the process by attacking solid rock at the Earth's surface, breaking it down into smaller pieces.

How does gravity contribute to the movement of weathered debris?

Gravity moves the weathered debris downslope in a process called mass wasting, which can range from slow creep to rapid landslides.

What happens to debris once it reaches a stream?

Once the debris reaches a stream, moving water transports it away as part of the erosion process.

Why are weathering, mass wasting, and erosion considered external processes?

These processes occur at or near Earth's surface, and their energy source is the sun, making them external processes.

How do external processes affect the rock cycle?

External processes transform solid rock into sediment, which is a fundamental part of the rock cycle.

What role does the sun play in external processes?

The sun provides the ultimate source of energy for external processes such as weathering, mass wasting, and erosion.

Why hasn't the surface of the moon changed much over the past two billion years?

The moon lacks an atmosphere and hydrosphere, so external processes like weathering and erosion do not occur there.

How do internal processes differ from external processes?

Internal processes are constructional and increase land elevation, while external processes lower land elevation through weathering and erosion.

Where does the energy for internal processes come from?

Internal processes derive energy from Earth's interior, which includes the cooling of the planet and the decay of radioactive isotopes.

What would happen if Earth had no atmosphere or hydrosphere?

Without an atmosphere or hydrosphere, external processes like weathering and erosion would not operate, similar to conditions on the moon.