Weathering vs. Erosion vs. Deposition: Differences, Real Examples and Earth Science Quiz

Key facts

• Weathering changes or breaks down rock in place without sediment transport.
• Erosion is removal and movement of rock or sediment by processes such as moving water, wind, ice or gravity.
• Deposition occurs when transported sediment is dropped and accumulates, for example in a river delta or sand dune.
• Physical weathering changes rock size and shape without requiring a change in mineral composition.
• Chemical weathering changes minerals through processes such as dissolution or oxidation.

Weathering breaks down rock in place, erosion moves rock and sediment away, and deposition occurs when transported material settles and accumulates. These three processes work together to reshape cliffs, rivers, canyons, beaches and deserts. The most important distinction is whether the material is being changed, transported or left behind.

Weathering vs. erosion vs. deposition at a glance

Process	What happens?	Example	Key clue
Weathering	Rock breaks into smaller pieces or its minerals change where it is	Water freezing in a rock crack, or limestone dissolving	No removal of the material is required
Erosion	Rock, soil or sediment is removed and carried away	Running water transporting sand downstream	Material is moving from its original location
Deposition	Transported sediment settles or accumulates	Sand deposited as a river bar or wind-built dune	Material is laid down in a new place

The U.S. National Park Service (NPS) describes these processes in its official overview of weathering, erosion and deposition. The distinctions are useful for middle-school Earth science and high-school geology.

What is weathering? Physical and chemical examples

Weathering occurs at or near Earth’s surface and changes rock without requiring that the resulting sediment be transported. It includes physical processes that break rock apart and chemical processes that change minerals.

Physical or mechanical weathering

Physical weathering breaks rock into smaller fragments without fundamentally changing the minerals that make up the fragments. Common examples include:

• Freeze–thaw activity: where conditions allow water to enter cracks and freeze, repeated cycles can help widen fractures in rock.
• Root growth: roots growing into cracks can exert pressure and contribute to rock breakdown.
• Thermal expansion and contraction: temperature changes can contribute to stress and fracturing, depending on the rock and conditions.
• Salt crystal growth: crystals forming in pore spaces or cracks can exert pressure on rock surfaces.

A weathered rock may remain in its original place until a later process carries the loosened material away. For explanations and site photographs, see NPS: Weathering.

Chemical weathering

Chemical weathering changes mineral composition. For example, slightly acidic natural water can dissolve carbonate minerals such as calcite in limestone, while oxygen and water can alter some iron-bearing minerals through oxidation. These processes can weaken rock and alter landscapes, even when no obvious pieces have broken off.

Not every visible crack signals one particular cause. Geologists use the material, local climate and surrounding evidence to distinguish processes.

What is erosion? Water, wind, glaciers and gravity

Erosion is the removal and transport of rock or sediment. A stream may pick up loose particles and move them downstream. Wind can move sand and dust. Glaciers can erode underlying rock and transport sediment. Gravity drives material downslope through mass wasting, which is often taught alongside erosion.

Consider a coastal cliff. Rain, waves and changing conditions may weather its materials; waves and moving water can then remove loose fragments. The featured real-world photograph shows erosion of Pleistocene boulder clay along cliffs in Filey Bay, Yorkshire, England. It illustrates coastal erosion, not a controlled laboratory test or a prediction about future cliff retreat.

According to the NPS field explanation from Scotts Bluff National Monument, wind and runoff can remove products of weathering, helping shape the bluffs.

What is deposition? Where sediments settle

Deposition takes place when sediment carried by water, wind, ice or gravity is left behind. A river may deposit part of its sediment load where conditions slow the flow. Wind can build a sand dune as transported grains collect. A glacier may leave deposited sediment as it melts or retreats.

Whether a location is experiencing erosion or deposition depends on local flow conditions and sediment supply. A river bend can erode along the outside bank while depositing sand on the inside bank. This makes it possible for both processes to occur close together.

Follow one grain of sand: a complete process

1. Weathering: A sandstone surface breaks apart, releasing a grain.
2. Erosion: Rainwater or a stream picks up the grain and moves it downslope.
3. Transport: Water carries the grain farther along the channel; transport is part of the broader erosional process.
4. Deposition: The grain settles where the stream can no longer keep it moving.
5. Later changes: Over time, some deposited sediment may be buried and lithified into sedimentary rock, which can weather again if exposed.

This last step connects weathering, erosion and deposition to the rock cycle. There is no rule that every grain follows the same sequence at the same speed; landscapes change over many timescales.

Real-life examples: classify each process

Observation	Process	Why?
A tree root gradually widens a crack in bedrock	Weathering	The rock is altered in place
Rainwater washes loosened soil down a hillside	Erosion	Soil is removed and transported
A stream leaves a new sandbar in a slower section	Deposition	Transported sand accumulates
Acidic water slowly dissolves carbonate minerals	Chemical weathering	Minerals change chemically
Wind carries grains away from a dry exposed surface	Erosion	Grains are transported
Wind drops grains to build a dune	Deposition	Sediment accumulates at a new site

Safe observation activity for students

Choose a safe, permitted outdoor location—such as a schoolyard, park path or gravel-covered area—and observe changes after rain, without entering waterways, climbing unstable slopes or disturbing protected areas. Look for cracked rock that remains in place, small channels where sediment was washed away, and deposits of silt or sand where runoff slowed. Record an observation and explain which process best fits it. Photographs taken on different dates can help show change, but one photograph rarely establishes exactly when a landform formed.

Practice quiz: weathering, erosion or deposition?

1. Water freezes in a crack and breaks a rock apart. Which process?
2. A fast-flowing stream carries pebbles downstream. Which process?
3. Sand settles at the mouth of a river. Which process?
4. Iron-bearing minerals chemically oxidize near the rock surface. Which process?
5. A dune grows as wind drops sand behind an obstacle. Which process?
6. Can weathering happen before erosion but without immediate sediment movement?

Answer key

1. Physical weathering. The rock breaks down in place.
2. Erosion. Material is being transported by water.
3. Deposition. Transported sediment settles.
4. Chemical weathering. Mineral composition is changing.
5. Deposition. Sand grains accumulate.
6. Yes. Weathered material can remain where it formed until later transported.

Related lessons and primary sources

Build on this explanation with our rock cycle lesson and earthquake magnitude vs. intensity guide. The primary educational references for this article are NPS: Weathering, Erosion and Deposition, NPS: Weathering and NPS: Weathering and Erosion at Scotts Bluff.

Educational guide reviewed November 9, 2026. Image: real coastal erosion at Filey Bay, photographed by Wilson44691 in June 2015; Wikimedia Commons, CC0 1.0. The image shows a specific English coastline and does not imply the same processes occur at identical rates everywhere.