---
title: "Coasts on the Move"
description: "Waves erode coastal rock, move sediment along the shore and deposit it where conditions allow. These processes shape headlands, bays, beaches, spits and bars."
canonical: https://lightmysky.com/learn/geography/coasts-on-the-move-mt_IVnXDRpfqE
source: https://lightmysky.com/learn/geography/coasts-on-the-move-mt_IVnXDRpfqE.md
retrieved: 2026-11-12
---

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# Coasts on the Move

Waves erode coastal rock, move sediment along the shore and deposit it where conditions allow. These processes shape headlands, bays, beaches, spits and bars.

Subject: Geography · Area: Physical Geography · Ages 11 to 13
Page: https://lightmysky.com/learn/geography/coasts-on-the-move-mt_IVnXDRpfqE

## Ready when they can

- Explain how waves arriving at an angle move sediment along a beach
- Say how a headland and a bay form on a coast made of alternating hard and soft rock
- Name one coastal landform made by erosion and one made by deposition

## Lesson: Coasts That Never Sit Still

When waves approach a beach at an angle, swash carries sand up the beach at that angle. Backwash returns down the slope under gravity, usually towards the sea. Repeated trips move sediment in a zigzag along the shore. This is longshore drift.

*(drawing: The boxes show repeated movements, not a map of the beach.)*

Where bands of more and less resistant rock meet the sea along a coast, less resistant rock usually erodes faster into bays. More resistant rock remains as headlands. Wave erosion can form cliffs, caves, arches and stacks. Deposition of sand or shingle can build beaches, spits and bars.

**Example.** If longshore drift carries sand east, it can supply beaches further east. A groyne extends out across a beach. It traps some sediment on the side from which drift arrives. Less may reach the next beach, where erosion can then increase.

A seawall runs along the shore and protects land behind it from waves. It does not trap drifting sand in the same way as a groyne. On suitable sheltered shores, marsh stems can slow water and trap sediment. Roots help hold the soil. Protection depends on the site and storm.

**Recap.** Angled swash and returning backwash move sediment alongshore. Erosion shapes rock, while deposition builds sediment landforms.

*Lesson, question and flashcard revisions written for this dataset.*

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Erosion and weathering](https://lightmysky.com/learn/science/erosion-and-weathering-mt_vAP_A986IQ)

## Optional connections

- [From Source to Sea](https://lightmysky.com/learn/geography/from-source-to-sea-mt_VuUB9PiYan)

## Opens up

- [Choosing How to Defend a Coast](https://lightmysky.com/learn/geography/choosing-how-to-defend-a-coast-mt_3Px4N4va3o)
- [What the Ice Left Behind](https://lightmysky.com/learn/geography/what-the-ice-left-behind-mt_D-aB1k0K73)
- [Reading a Landscape Off a Map](https://lightmysky.com/learn/geography/reading-a-landscape-off-a-map-mt_MWlY_e59Rg)