How do weathering, erosion and deposition break down, move and lay down Earth's materials?
Distinguish mechanical and chemical weathering, identify the agents of erosion and deposition, and explain how particle size, sorting and water velocity control where sediment is deposited (Virginia 2018 Earth Science SOL ES.6 surface processes).
A SOL-level answer on surface processes for the Virginia Earth Science EOC: mechanical versus chemical weathering and what speeds each, the agents of erosion (water, wind, ice, gravity), how water velocity controls the size of sediment carried and deposited, sediment sorting and rounding, and landforms like deltas and moraines, with worked exam questions.
Reviewed by: AI editorial process; not yet individually human-reviewed
Have a quick question? Jump to the Q&A page
Jump to a section
What this topic is asking
Virginia Earth Science SOL standard ES.6 (the surface-processes content) asks you to distinguish weathering (breaking rock down) from erosion (moving the pieces) and deposition (dropping them), to know the agents that do the moving, and to explain how water velocity and particle size control where sediment ends up. The EOC tests this with cause-and-effect items (what happens when a river slows), classification items (which kind of weathering), and graph items linking stream velocity to the size of particle it can carry.
Weathering: mechanical versus chemical
Climate sets the pace: mechanical weathering dominates in cold climates (lots of freeze-thaw), and chemical weathering dominates in warm, wet climates (faster reactions). Smaller fragments have more surface area per volume, so they weather faster, which is why mechanical and chemical weathering speed each other up.
Erosion: the agents of transport
The key contrast students must keep straight: weathering breaks rock apart in place, while erosion moves the pieces away.
How water velocity controls deposition
This is why a graph of stream velocity versus particle size is a classic EOC stimulus: read off the largest particle a given velocity can transport.
Landforms of deposition
Where sediment is deposited builds recognizable landforms. A delta forms where a river enters a still body of water and drops its load. A floodplain is the flat, fertile land beside a river built from deposited sediment during floods. An alluvial fan forms where a fast mountain stream slows on reaching a plain. Glaciers deposit unsorted sediment called till, building ridges called moraines and other features such as U-shaped valleys, distinguishing glacial deposition from the sorted deposits of water.
Try this
Q1. State one difference between mechanical and chemical weathering, with an example of each. [2]
- Cue. Mechanical weathering breaks rock without changing its composition (frost wedging); chemical weathering changes the composition (acid dissolving limestone).
Q2. Explain why a slow-moving stream deposits fine sediment but a fast one can carry boulders. [2]
- Cue. Faster water has more energy and can transport larger, heavier particles; a slow stream has little energy, so it can only carry (and deposit) fine particles.
Exam-style practice questions
Practice questions written in the style of VDOE exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
VA Earth Science SOL 2023 (style)1 marksWater freezing and thawing in the cracks of a rock, slowly breaking it apart, is an example of which process? (A) chemical weathering. (B) mechanical weathering. (C) deposition. (D) erosion.Show worked answer →
A 1-point multiple-choice item on weathering type.
The correct answer is B. Frost wedging (ice expanding in cracks) physically breaks rock apart without changing its chemical makeup, so it is mechanical (physical) weathering. Chemical weathering (A) would change the rock's composition (such as acid dissolving limestone). Deposition (C) and erosion (D) are about moving and dropping sediment, not breaking the rock in place.
The test rewards classifying frost wedging as mechanical weathering, because the rock is broken but not chemically changed.
VA Earth Science SOL 2024 (style)2 marksA fast-moving river slows down sharply as it enters a calm lake. (a) Explain what happens to the sediment the river was carrying. (b) Explain why the largest particles are deposited first.Show worked answer →
A 2-point item on deposition.
(a) 1 point: as the water slows, it loses energy and can no longer carry its sediment, so the sediment is deposited (dropped), often building a delta where the river meets the lake.
(b) 1 point: larger, heavier particles need more energy (faster water) to stay suspended, so when the water slows they settle out first; smaller, lighter particles stay suspended longer and are deposited farther out.
Markers reward linking slower water to deposition in (a) and the idea that larger particles need more energy and settle first in (b).
Related dot points
- Describe the components of soil and the soil horizons, explain the factors that control soil formation, and evaluate soil as a resource that can be conserved or lost to erosion (Virginia 2018 Earth Science SOL ES.6 surface processes).
A SOL-level answer on soil for the Virginia Earth Science EOC: the components of soil (weathered rock, humus, water, air), the O, A, B and C horizons, the factors that control soil formation (climate, parent material, time, organisms, slope), residual versus transported soil, and why soil conservation matters, with worked exam questions.
- Read a topographic map: interpret contour lines and the contour interval, find elevation and relief, judge slope steepness from contour spacing, and use the rule of Vs to find stream direction (Virginia 2018 Earth Science SOL ES.1 and ES.6).
A SOL-level answer on topographic maps for the Virginia Earth Science EOC: what contour lines and the contour interval mean, how to find elevation and total relief, how contour spacing shows slope steepness, how the rule of Vs gives stream direction, and how to calculate gradient, with worked exam questions.
- Classify igneous, sedimentary and metamorphic rocks by how they form and explain the rock cycle, including how cooling rate, lithification, and heat and pressure transform rock (Virginia 2018 Earth Science SOL ES.5).
A SOL-level answer on rocks for the Virginia Earth Science EOC: how igneous, sedimentary and metamorphic rocks form, the link between cooling rate and crystal size, clastic versus chemical sediment, foliated versus nonfoliated metamorphic rock, and how the rock cycle transforms one type into another, with worked exam questions.
- Explain the processes of the water cycle (evaporation, transpiration, condensation, precipitation, runoff, infiltration) and describe watersheds, groundwater and the water table (Virginia 2018 Earth Science SOL ES.9 and ES.10).
A SOL-level answer on the water cycle for the Virginia Earth Science EOC: the processes that move water (evaporation, transpiration, condensation, precipitation, runoff, infiltration), the energy that drives it, what a watershed and divide are, groundwater and the water table, and porosity and permeability, with worked exam questions.
- Apply the principles of relative dating (superposition, original horizontality, cross-cutting relationships, inclusions and unconformities) to sequence events in a geologic cross section (Virginia 2018 Earth Science SOL ES.9).
A SOL-level answer on relative dating for the Virginia Earth Science EOC: the law of superposition, original horizontality, cross-cutting relationships, inclusions and unconformities, the difference between relative and absolute age, and how to sequence the events in a geologic cross section, with worked exam questions.
Sources & how we know this
- 2018 Science Standards of Learning (Earth Science) — Virginia Department of Education (2018)
- SOL Practice Items (All Subjects) — Virginia Department of Education (2024)