Coasts: erosion and features

How waves shape coastlines and the features that result

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Try each question. If you're stuck, leave it and come back. The answer key is on the last page.

1
Put these features in order showing how coastal erosion creates a stack. Put these in order: Arch, Cave, Crack in cliff, Stack
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2
Complete the sentence. A piece of land sticking out into the sea is called a ___.
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3
True or false? Bays form where softer rock is eroded away faster than the harder rock around it. A) True B) False
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4
What is coastal erosion? A) When the sea wears away the land B) When the sea drops sand on the beach C) When rivers form deltas D) When the wind blows leaves
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5
Which type of erosion happens when waves trap and compress air in cracks? A) Hydraulic action B) Abrasion C) Attrition D) Solution
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6
Match each type of erosion to its definition. Match each item on the left to one on the right. Left: Hydraulic action, Abrasion, Attrition, Solution Right: Pressure from waves trapped in cracks, Waves throw rocks against the cliff, Rocks knock together and become smaller and rounder, Seawater dissolves rocks like limestone
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7
What forms when an arch eventually collapses? A) A stack B) A new cave C) A bay D) A beach
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8
Complete the sentence. When a stack is worn down to a small lump in the sea, it is called a ___.
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9
Why is the cliff at the back of a beach gradually moving inland? A) Waves erode the base of the cliff, so the top collapses B) The sea level is rising and pushing the cliff back C) Wind blows the cliff inland D) Cliffs always move on their own
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10
Order these stages in the formation of a stump. Put these in order: Stack, Arch, Stump, Cave
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Answer key

Coasts: erosion and features · for parents and teachers

1
Crack in cliff, Cave, Arch, Stack
Coastal erosion of a headland follows the sequence: crack, cave, arch, stack, stump. Waves widen weaknesses until cliffs collapse.
2
headland
A headland is a section of resistant rock that sticks out into the sea. The softer rock either side is eroded faster, leaving bays in between.
3
True
Bays form where the sea erodes softer rock more quickly, creating a curve in the coastline. Harder rock either side juts out as headlands.
4
When the sea wears away the land
Coastal erosion is when the sea slowly wears away the coast.
5
Hydraulic action
Hydraulic action happens when waves crash into cracks, trapping and compressing air. The pressure widens the crack each time, eventually breaking the rock.
6
Hydraulic action → Pressure from waves trapped in cracks; Abrasion → Waves throw rocks against the cliff; Attrition → Rocks knock together and become smaller and rounder; Solution → Seawater dissolves rocks like limestone
The four main types of coastal erosion are hydraulic action (pressure), abrasion (rocks hitting cliffs), attrition (rocks hitting each other), and solution (dissolving).
7
A stack
When the top of an arch is no longer supported, it collapses, leaving a tall column of rock standing in the sea. This is called a stack.
8
stump
When a stack continues to erode and collapses, only a small lump remains, called a stump. It is often only visible at low tide.
9
Waves erode the base of the cliff, so the top collapses
Waves erode the base of cliffs, creating an undercut. Eventually the unsupported rock above collapses. This process, called cliff retreat, moves the cliff inland over time.
10
Cave, Arch, Stack, Stump
Erosion of a headland forms a cave, then an arch (when caves join through the headland), then a stack (when the arch collapses), then a stump (when the stack erodes).