🌍 EarthCache: Mundesley EarthCache

Important Safety and Conservation Notice

Mundesley is an actively changing coastline. Please:

• Keep off the cliff faces and do not stand beneath overhangs – the cliffs here are soft and can collapse without warning.
• Use the promenade, ramps and marked access points; do not climb the sea wall or cliff slopes.
• Be tide aware – sections of the beach reduce significantly at high tide.

The cliff line here forms part of the Mundesley Cliffs SSSI, designated for its important geological exposures. All logging tasks are completed from the public beach or promenade outside the protected cliff face. Please respect all fences and signage.

Logging Tasks

You will make observations at the published coordinates (promenade frontage, sea wall and cliffs above) and at an additional waypoint (a short walk to where the natural cliff face is exposed beyond the sea wall). Please answer all questions:

1. Cliff Materials – Identify at least two different types of material visible in the cliff (for example: clay/till, sand, gravel). Describe their colour and texture.
2. Layering – Can you see distinct layers in the cliff face? Are they horizontal, tilted, or uneven? Describe one clear layer and how it differs from the one above or below it.
3. Instability – Look for signs of how these soft cliffs are failing. Do you see slumps, cracks, or fallen debris at the base? Describe at least one feature.
4. Sea Wall – At the EC coordinates, observe the sea wall. Do you notice drainage outlets, repairs, or signs of undercutting? Summarise how the wall interacts with the cliff above.
5. Defended vs. Natural – Compare the defended section (EC coords) with the natural section (waypoint). How does the cliff appearance differ in terms of materials exposed and erosion evidence?
6. Glacial Legacy – Based on your observations, explain in your own words why these soft glacial cliffs erode faster than hard rock cliffs elsewhere in the UK.

Optional photo: You may include a photo of yourself or your GPS on the promenade or beach, but please do not show your answers.

The Earth Science Lesson

The cliffs at Mundesley are very different from the hard rocky cliffs you might see in places like Dorset or North Yorkshire. Instead, they are made of soft sediments left behind during the Ice Age. These materials are so important that the site is protected as the Mundesley Cliffs SSSI.

Ice Age Origins

Around 450,000 years ago, during the Anglian glaciation, huge ice sheets covered much of East Anglia. As the glaciers advanced and retreated, they left behind a mixture of materials known as glacial sediments. At Mundesley, these include:

• Till (boulder clay) – a sticky, clay-rich deposit with scattered stones dropped directly by melting ice.
• Sands and gravels – laid down by meltwater rivers flowing from the glacier.
• Occasional organic layers – from ancient rivers, marshes or forests that existed between glacial advances.

Why These Cliffs Erode Quickly

Unlike hard rocks such as limestone or granite, these sediments are unconsolidated – they were never cemented into solid rock. This means they are weak and easily eroded by the sea. Waves remove sand at the base, while rainwater soaks in from above, causing slumps and collapses. You can often see layers of different colours and textures in the cliff face, showing the history of the Ice Age deposits as they are revealed by erosion.

Natural vs. Managed Coastline

At Mundesley village, a sea wall and promenade have been built to protect houses and businesses. However, the cliffs above remain unstable, with cracks and slumps still visible. A short walk away, where no wall exists, the natural cliff shows clear signs of erosion and retreat. By comparing the two sections, you can see how human management interacts with natural processes, but does not stop them altogether.

Sources of Information

• Natural England – Mundesley Cliffs SSSI citation (designated for its Pleistocene glacial exposures).
• British Geological Survey – Geology of East Anglia (Anglian glaciation and deposits).
• Norfolk Coast AONB – Geological Landscapes: Cromer Ridge and glacial sediments.
• Environment Agency – Shoreline Management Plan, Unit 6.12: Mundesley.