Chapter 5 - Weathering and Soil Flashcards
What is mechanical weathering?
The breaking of rocks into smaller pieces without changing their chemical composition
What is chemical weathering?
The decomposition of rocks through chemical reactions.
What are the most common types of mechanical weathering?
Frost wedging, sheeting, and biological activity.
What is oxidation in weathering?
A chemical reaction where a mineral reacts with oxygen, often seen in the rusting of iron.
What is soil?
A mixture of mineral and organic matter that supports plant growth.
How do mechanical and chemical weathering processes interact to shape landscapes?
Mechanical weathering increases the surface area exposed to chemical weathering, speeding up the overall breakdown of rock and leading to soil formation and landform changes.
Why is soil considered an interface between the biosphere, geosphere, hydrosphere, and atmosphere?
Soil is where these four spheres meet, interact, and support plant life, making it a critical boundary for nutrient cycling and ecosystem support.
What are Earth’s external processes?
Weathering, mass wasting, and erosion
What is weathering?
The physical breakdown (disintegration) and chemical alteration (decomposition) of rocks at Earth’s surface
How does frost wedging cause weathering?
Water seeps into cracks, freezes, expands, and breaks the rock apart
What is sheeting in weathering?
Erosion exposes large igneous rocks, leading to the peeling off of slabs, forming exfoliation domes
How do plants contribute to mechanical weathering?
Roots grow into fractures, expanding them and allowing water and chemicals to infiltrate
What is hydrolysis in chemical weathering?
A reaction where water breaks down minerals, replacing ions and weakening the rock structure
What factors affect the rate of weathering?
Rock characteristics (silicate vs. calcite) and climate (temperature and moisture)
What are the key controls of soil formation?
Parent material, time, climate, plants/animals, and topography
