Deposition Lab

◫ River → delta

Mode

Mission: Build a delta

Start the flow. Change water speed and grain size; watch where sediment settles.

1Choose a demo

2Press Start

3Tap the scene

Water flowSedimentSelected

Experiment

Conditions

Flow speed1.2 m/s

Median grain size0.50 mm

Sediment supply55%

Simulation speed1.00×

Camera & focus

Zoom1.00×

Live evidence

Settling speed0.15 cm/s

Transport capacity68%

Deposited0 grains

Delta growth0.0 cm

Paused. Press Start to release sediment into the current.

Deposition history

TransportedDeposited

Teacher tools

Relative sea level0 cm

Reveal extended explanation

Guided deposition lesson

Press Start. The camera, labels, animation, transcript, and voice will advance together.

Ready. Lecture is stopped.

Step 1 of 1010%

Watch on the canvas

Sediment enters the river and follows the current.

1. What is deposition?

Deposition happens when moving water, wind, ice, or gravity loses enough energy to drop the material it carries.

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Language and voice settings

LanguageVoice sourceVoice

Learning objectives

Predict where sediment will settle as flow energy changes.
Relate grain size and density to settling speed.
Explain sorting and layered deposits.
Compare river, beach, wind, and glacial deposition.

Key concepts

Deposition is the laying down of transported material. In this model, a grain settles when its downward settling and the weakening current bring it to the bed. Larger quartz grains generally settle faster than fine silt, while fast flow can keep more material moving.

The shown settling speed is an educational approximation based on grain size, gravity, water viscosity, and density contrast. The visible grain size and delta growth are enlarged so changes can be studied.

Try these experiments

Set flow above 2 m/s, then suddenly reduce it below 0.5 m/s.
Compare 0.1 mm silt with 1.5 mm sand at the same flow.
Use Beach sorting and watch waves move fine grains farther.
Raise sea level in Teacher Mode and observe the shoreline shift.

Explore further

Questions: Why do deposits become finer downstream? Why can a flood both erode and later deposit sediment?

Applications: Delta building, reservoir silting, beach nourishment, dune migration, floodplain soils, and interpreting ancient rock layers.

Common misconception: Deposition is not caused by grains “running out” on their own. It occurs because transport energy, slope, flow, or supporting turbulence decreases.

Deposition check

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