🌍 Winterton - Dynamic Dunes & Coastal Erosion EarthCache

Important Safety and Conservation Notice

This is an actively eroding coastline with fragile dune habitats. Please take care and follow these guidelines:

• Stay on designated paths and walkways—walking directly on the dunes damages vegetation and destabilises them.
• Do not stand directly beneath dune faces—they are unstable and may collapse without warning.
• Do not climb cliffs or dunes.
• Be aware of tide times—the lower beach may become inaccessible at high tide.

The beach itself is public access and outside the SSSI boundary. However, the dunes directly behind are protected as the Winterton–Horsey Dunes Site of Special Scientific Interest (SSSI) and National Nature Reserve (NNR). These habitats are home to rare species such as natterjack toads, adders, and ground-nesting birds. Please respect the environment, stick to the paths, and avoid disturbing wildlife.

Logging Tasks

To claim this EarthCache, you will need to make observations at two locations:

• The published coordinates at the main dune face.
• And where you enter the beach from either side as you walk to the posted co ordinates.

Please ensure you walk between these points—this EarthCache has been designed to give you the full picture of how this coastline is changing.

1. Dune Height & Profile – At the main coordinates, estimate the dune’s vertical height (e.g. your height, twice your height, more?). Describe whether the slope looks gentle, moderate, or very steep.
2. Signs of Erosion – Identify two visible features that show erosion is active here (examples include collapsed sand, exposed roots, debris, or slumping).
3. Beach Sediment – At the waypoint, look closely at the material beneath your feet. Is it mainly fine sand, coarse sand, shingle, or a mixture? How might this affect how easily the beach is eroded or reshaped?
4. Vegetation Evidence – Compare the two sites. Where do you see marram grass or other plants, and where is it absent? What does this suggest about dune stability versus active erosion?
5. Process Balance – From what you can see, is this stretch of coast currently dominated by erosion or deposition? Explain your reasoning with evidence from your visit.
6. Longshore Drift – Looking along the shoreline, do you notice angled ridges, swept sand patterns, or bars that suggest sediment movement? Which direction does the material appear to be moving?

Optional Photo – You are welcome to include a photo of yourself or your GPS with the dunes or beach in view (please do not show your answers).

The Geological Lesson

When you arrive at Winterton-on-Sea, the first thing that strikes you is how open and windswept the beach feels, with the tall sand dunes forming a backdrop behind you. It is here that natural forces and time are working against each other, and you can see the results with every step.

Origins of the Coastline

The cliffs and dunes here are built from soft sands and gravels laid down during the last Ice Age. Unlike hard rock coasts, these loose materials are easily shifted by wind and water, which makes this one of the most dynamic stretches of Norfolk’s shoreline.

Sand Dunes

As you walk along the beach, look up to the dunes. They are held together by plants like marram grass, which act as nature’s glue with deep roots that bind the sand. Where the grass is thick, the dunes look stable and rounded. Where there is little or no vegetation, the dunes appear bare and fragile, more easily eaten away by the sea.

Aeolian and Marine Processes

Two forces shape these dunes:

• Wind (aeolian processes) blows dry sand inland, feeding the dune system.
• Waves and tides (marine processes) undercut the dune base, causing sudden collapses and slumps.

Stand back and you’ll notice how the wind builds, while the waves destroy—a constant push and pull that never ends.

Coastal Erosion

At the main coordinates you can see steep vertical dune faces where the sea has bitten into the coast. Roots dangle, sand slumps in piles, and the cliff line edges ever further back. Every winter storm accelerates this retreat, reshaping the coastline once again.

Seasonal Variation

Like many beaches, Winterton is seasonal in character. In winter, storms dominate and erosion is most obvious. In summer, calmer waves often redeposit sand on the beach, occasionally giving the impression that the coast has recovered—until the next storm season arrives.

Sediment Budget and Longshore Drift

Sand lost from these dunes is not gone forever. Longshore drift transports much of it southwards, helping to feed beaches further along the coast. This movement is part of the region’s sediment budget, where erosion at Winterton supplies material that supports other areas.

Human Influence

If you look carefully you may find remnants of old sea defences, but much of this coast is now managed by allowing nature to take its course. By permitting erosion here, sediment continues to supply beaches elsewhere, keeping the wider system in balance.

Dynamic Balance

Winterton is a place where you can watch geomorphology in action. Erosion, deposition, vegetation growth, and storm damage all combine to make a landscape that never looks the same twice. It is a reminder of how powerful natural processes are, and how difficult it is to resist them.

Wentworth Grain Size Scale (Scientific)

Size Class – Grain Diameter (mm) – Common Term

• Boulder – > 256 mm – Large rock / boulder

• Cobble – 64 – 256 mm – Cobble

• Pebble – 4 – 64 mm – Pebble

• Granule – 2 – 4 mm – Granule

• Sand (Very Coarse) – 1 – 2 mm – Very coarse sand

• Sand (Coarse) – 0.5 – 1 mm – Coarse sand

• Sand (Medium) – 0.25 – 0.5 mm – Medium sand

• Sand (Fine) – 0.125 – 0.25 mm – Fine sand

• Sand (Very Fine) – 0.0625 – 0.125 mm – Very fine sand

• Silt – 0.0039 – 0.0625 mm – Silt

• Clay – < 0.0039 mm – Clay

Source: Wentworth, C.K. (1922). A Scale of Grade and Class Terms for Clastic Sediments. Journal of Geology, Vol. 30, No. 5, pp. 377–392.

Simple Field Guide to Grain Sizes

• Boulder = anything bigger than a football

• Cobble = fist-sized to football-sized

• Pebble = marble up to golf-ball size

• Granule = larger than a grain of rice but smaller than a pea

• Sand (coarse to fine) = anything from sugar-sized grains down to flour-like grains

• Silt = smooth like talcum powder when dry; gritty when rubbed wet between fingers

• Clay = sticky and mouldable when wet; very smooth when dry

Sources of Information

• Broads Authority (2021) – Coastal Processes within the Plan Area.
• Winterton-on-Sea Community Website – Coastal Erosion & Sea Defence History (wintertononsea.co.uk).
• Environment Agency – Shoreline Management Plan 6 (Kelling to Lowestoft Ness) (environment.data.gov.uk).
• Wikipedia – Winterton Dunes; Aeolian Processes; Longshore Drift (accessed 2025).
• Britannica – Wentworth Grade Scale provides a concise definition of the Udden–Wentworth grain-size scale and explains its geometric structure, noting how it’s commonly used in sedimentology.
• Natural England – Winterton–Horsey Dunes SSSI information (designation and boundaries).