Weathering, Soil, and Erosion Concepts

Vocabulary flashcards covering key concepts from weathering, soils, erosion, and land degradation.

Mechanical weathering

The physical breakdown of rock into smaller pieces without changing its chemical composition; occurs via freezing and thawing, abrasion, or plant root growth.

Chemical weathering

The process of rock being altered or dissolved due to chemical reactions, often involving water, oxygen, or acids, changing mineral composition over time.

Carbonic acid

A weak acid formed when carbon dioxide dissolves in water; plays a major role in weathering limestone and other carbonate rocks.

Tannic acid

An organic acid released from decaying leaves and plants, especially in forests; can contribute to chemical weathering of rocks and soils.

Soil

A mixture of weathered rock, minerals, water, air, and organic material that supports plant life; forms the uppermost layer of Earth’s surface.

Horizon

A distinct soil layer that differs in color, texture, and composition from layers above and below; altogether they make up a soil profile.

Humus

Dark, organic material in soil formed from decomposed plant and animal matter; enriches soil by providing nutrients and improving structure.

Residual soil

Soil that forms directly from the weathering of the bedrock beneath it; remains in the same place as the rock it developed from.

Transported soil

Soil that has been moved from its place of origin by wind, water, glaciers, or gravity; composition often differs from the local bedrock.

Erosion

The movement of weathered rock and soil from one location to another by wind, water, ice, or gravity; a key process shaping Earth’s surface.

Deposition

The process of sediments being laid down or settled in a new location after being transported; examples include deltas and sand dunes.

Carrying power

The ability of a stream or river to move sediment based on its speed and volume; faster, larger streams can transport bigger and heavier particles.

Tributary

A smaller stream that flows into a larger one.

Headwaters

The source or beginning of a river.

Mouth

The point where a river empties into a larger body of water.

Turbidity

The cloudiness of water due to fine particles suspended in it; sediments in suspension can be carried long distances before settling.

Sorting

The process by which sediments are separated by size and weight during transport; well-sorted sediments indicate consistent energy conditions (e.g., beach sand).

Overgrazing

When animals graze vegetation excessively, preventing regrowth and leaving soil exposed; accelerates erosion and land degradation.

Desertification

Transformation of fertile land into desert-like conditions, often caused by overgrazing, deforestation, drought, or poor land management.

Buffer zone

An area of vegetation or undeveloped land placed between ecosystems and human activities; reduces erosion, filters runoff, and protects water quality.

Porosity

The percentage of open spaces (pores) in soil or rock that can hold water or air; higher _____ means more storage capacity.

Permeability

The ability of soil or rock to allow water to pass through it; high ______ materials, like sand, let water flow easily, while clay has low _______.