Exogenic Processes: Weathering Overview

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Questions and Answers

Which of the following is NOT a process of physical weathering?

Abrasion

Frost wedging

Oxidation (correct)

Biological activity

Chemical weathering involves the breakdown of rocks without any change to the rock's minerals.

False

What is the main difference between physical and chemical weathering?

Physical weathering breaks rocks into smaller pieces without changing their composition, while chemical weathering involves changes in the rock's minerals.

___ is a process where water gets into rock joints, and alternate freezing and thawing causes the rock to break apart.

Frost wedging Signup and view all the answers

Match the following weathering processes with their descriptions:

Dissolution = Dissociation into ions Oxidation = Reaction with oxygen Hydrolysis = Reaction with water Salt crystal growth = Expansion from crystallization Signup and view all the answers

Which factor is NOT mentioned as affecting weathering?

Pressure Signup and view all the answers

Physical weathering typically occurs at a faster rate on gentle slopes compared to steep slopes.

False Signup and view all the answers

Name one natural agent that can cause physical weathering.

Water, plants, or animals Signup and view all the answers

What is the primary effect of frost wedging in physical weathering?

Breaking rocks apart through freezing and thawing Signup and view all the answers

Which factor would most likely increase the rate of chemical weathering?

Warm and wet climates Signup and view all the answers

How does the type of rock affect weathering rates?

Following the order of crystallization in Bowen's reaction series Signup and view all the answers

What role do biological activities play in physical weathering?

They assist in breaking rocks through plant and animal interactions. Signup and view all the answers

Which of the following describes the process of hydrolysis in chemical weathering?

Change in mineral composition through reaction with water Signup and view all the answers

In what way does topography influence physical weathering?

Steep slopes promote faster weathering due to mass wasting. Signup and view all the answers

What is dissolution in the context of chemical weathering?

Dissociation of molecules into ions, such as salt dissolving in water. Signup and view all the answers

Which of the following statements about weathering is incorrect?

Physical weathering occurs at a slower rate on steep slopes. Signup and view all the answers

Study Notes

Exogenic Processes: Weathering

Weathering is the breakdown of rocks at the Earth's surface, driven by rainwater, temperature changes, and biological activity.
Importantly, it does not involve the removal of rock material.
A recap question: what natural agents or processes break down rocks into smaller pieces?

Main Categories of Weathering Processes

Weathering is categorized as physical and chemical.
Weathering commonly occurs in situ (in place).

Physical Weathering Processes

Frost wedging: Water seeps into cracks, freezes, expands, and forces the rock apart.
Salt crystal growth: Dissolved salts in water evaporate, crystallize, and exert pressure on surrounding rock, causing it to break apart.
Abrasion: Rocks are worn away by the constant collision of loose particles.
Biological activity: Plants and animals (including humans) contribute to mechanical weathering.

Major Processes of Chemical Weathering

Dissolution: Molecules break down into ions – a classic example is the dissolving of salt.
Oxidation: A reaction occurs between minerals and dissolved oxygen in water.
Hydrolysis: Minerals react with water, changing their composition.

Factors Affecting Weathering

Climate:
Rock type: Weathering rates are roughly inversely related to the order of mineral crystallization in the Bowen's Reaction Series.Cold and dry climates result in slow chemical weathering, while high temperatures and rainfall contribute to rapid chemical weathering.
The minerals that crystallize first are typically less resistant to weathering.
Rock structure: Cracks and openings in rocks allow agents of weathering (water, plant roots, etc.) to enter more easily, speeding up the process.
Time: Longer exposure to weathering agents leads to a higher rate of weathering. The ro ck becomes progressively weaker over time.

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Description

Explore the fascinating world of weathering, a key exogenic process that breaks down rocks through various agents such as temperature changes, water, and biological activity. This quiz covers the main categories of weathering, including physical and chemical processes, and highlights specific mechanisms like frost wedging and salt crystal growth.