Coastlines: erosion

Many features of the coast have been created by erosion. This is when the sea wears away the land. Coastal erosion creates features like caves and sea stacks.

In this article you can find out:

• Different stages of coastal erosion
• How sea stacks are formed
• How tides can be used to generate electricity
• Scottish wildlife at sea

This resource is suitable for Landscapes topics for primary school learners.

Join Isla and Connor as they explore features of coastal erosion on a journey from Stromness in Orkney to Scrabster in the north of mainland Scotland.

• Scotland is surrounded by sea. The boundary between the sea and land is called the coast or coastline.
• Waves crashing up against the land cause erosion. Over time, all this erosion can change the shape of the coastline.

Erosion can create caves, arches, stacks and stumps along a headland.

A headland is a narrow piece of land that sticks out from the coast into the sea. Headlands are made of hard rock. They form when softer rock on either side is eroded. A headland is usually high up and has a steep drop.

1. Waves crash onto the headland and wear away the rock creating cracks.
2. Caves are formed when waves force their way into the cracks. The water contains sand and other materials that grind away at the rock until the cracks become a cave.
3. Over time, waves may eventually break through to the other side of a cave forming an arch.
4. The arch will gradually become bigger until it can no longer support the rock above it. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
5. The stack will be eroded at the bottom. This weakens the stack and it will eventually collapse to form a stump.

Another example of coastal erosion is a wave-cut platform. This is a flat area in front of a cliff, just below the low tide mark. This is the level where the tide is at its lowest.

Wave-cut platforms are formed when waves erode a cliff and leave a flat platform behind.

• Tides are the rising and falling levels of the ocean’s surface caused by the gravitational pull of the moon. The change between high and low tide happens twice a day.
• Tides in the ocean are caused by the gravity of the moon pulling the Earth towards it.
• Where oceans face the moon, the water is pulled most and builds up in a bulge. This is a high tide. The Earth is pulled towards the moon more than the ocean on the opposite side of the planet. This causes another high tide.
• As the moon moves around the planet, these tides move around with it, causes two high tides and two low tides each day.
• This moving water has a lot of kinetic energy that can be used to generate electricity.
• The Pentland Firth has some of the most powerful tides in the world. That's why Orkney is an important centre for renewable energy research.

Discover some of the wildlife you might spot around Scotland's coast.

You can read about the whales and dolphins spotted off Scotland's west coast on BBC News: The whales which have visited Scotland for 20 years

Spot some more coastal wildlife as Cumbrae Primary School explain why they think living on the coast is brilliant.

• coast - Where land meets sea. Also known as coastline.
• shore - The land along the edge of a sea, lake, or wide river.
• tides- The rising and falling levels of the ocean’s surface caused by the gravitational pull of the moon.
• renewable energy - An energy source that can be used again and again. Renewable energy includes solar, hydro and wind energy.
• high tide - When water covers most of the shore after rising to its highest level.
• low tide - When water retreats (goes back) to its lowest level, moving away from the shore.
• erosion - The wearing away of pieces of rock, soil or other solid materials.
• wave cut platform - A flat area in front of a cliff, just below the low tide mark. They are formed when waves erode the cliff and leave a flat platform behind.
• headland - An area of land that sticks out from the coast into the sea.
• cave - A natural opening in the Earth's surface. Most caves are created when water erodes or dissolves rock, creating an opening or passage.
• arch - A curved opening with a bridge, roof or wall above it. They can be formed in headlands when a cave has been eroded by the sea.
• sea stack - A tall column of rock. They are formed when erosion causes an arch in a headland to collapse.
• stump - A small pillar of rock left behind when a sea stack has collapsed.

Design a Viking longboat.

In the video at the top of the page, Isla explained that Vikings settled in Orkney hundreds of years ago.

The Vikings were expert sailors and were very good at shipbuilding. Their longboats could survive difficult sea journeys - like journeys from Norway to Scotland!

Try designing and building your own Viking longboat.

If you want to find out more about the Vikings in Scotland, take a look at these guides: Vikings in Scotland

Find out how we can use waves and tides to generate renewable electricity.