The Formation of the Beach

2: The Story of Sidmouth’s Shingle: Tides, Ice, and Time

Discover how the "Great Beach" of Sidmouth was formed. Learn about the Ice Age origins, the impact of longshore drift, and how human activity has shaped this 6,000-year-old shoreline.

The Sidmouth coastline, stretching from Peak Hill to Salcombe Mouth, is dominated by an expansive shingle beach. While it appears permanent, this habitat is a dynamic system shaped by thousands of years of glacial shifts and powerful Atlantic storms.

1. Ancient Origins: The Ice Age Legacy

The foundation of our modern shoreline was laid during the last Ice Age, which began approximately 2.5 million years ago.

Glacial Bulldozing: During warmer "interglacial" periods, rising sea levels acted like a giant bulldozer, pushing gravel from southern plains landwards to create early beaches.
The "Great Beach": Around 6,000 years ago, as sea levels stabilized following the last major glacial melt, a massive, continuous landform known as the "Great Beach" (or "West Beach") formed along the Jurassic Coast.
The Modern Ridge: The shingle ridges you walk on today beneath the Sidmouth Esplanade are the direct descendants of this ancient sequence of rising and falling seas.

2. What is Sidmouth Shingle Made Of?

The "stones" on the beach aren't just random rocks; they are a geological cocktail from diverse sources:

Material Original Source

Flint Local Chalk deposits

Chert Upper Greensand

Pebbles Budleigh Salterton Pebble Beds (BSPB)

Red Sand & Clay Added via cliff rock falls

River Sediment Historically contributed by the River Sid

3. Natural Forces: The Power of Waves

The beach is never truly still. For 6,000 years, gravity, wind, and waves have been the primary architects of the coast.

Longshore Drift: Most sediment moves eastwards along the Jurassic Coast. This regional drift originally created a massive, curved shingle ridge that stretched from Chit Rocks to East Beach.
Redirecting the River: This growing ridge was so powerful it actually grew across the lower Sid valley, forcing the River Sid’s outlet further to the east.
Wave Energy: Shingle beaches only develop where wave action is forceful enough to throw heavy coarse sediments high onto the shore.

4. The Human Impact: A Changing Shoreline

In recent centuries, human activity has significantly altered the natural lifecycle of the beach.

Disappearing Sediment: Since 1824, coastal structures have caused the "Main Beach" to shrink. Natural sediment sources are now often blocked by concrete defences or trapped upstream by river weirs.
Artificial Restoration: To protect the town, the beach has been artificially "topped up" with gravel imported from the Budleigh Salterton Pebble Beds.
Habitat Loss: Human pressure has unfortunately degraded much of the "vegetated shingle," a rare habitat where specialised plants once thrived on the stable stones.

Before you go

The Sidmouth Shingle Survey

This activity is designed for individuals or small groups to complete while walking from Jacob’s Ladder toward the River Sid.

Part 1: The "Geological Cocktail" Scavenger Hunt

Using the information from your article, challenge learners to find and identify one of each of the following stones. This helps them visualize the diverse sources of Sidmouth’s sediment.

The Ancient Traveler (BSPB Pebble): Look for a smooth, rounded, often pinkish or purple-toned quartzite pebble. These were transported and used for artificial augmentation.
The Glassy Sharp (Flint): Find a dark, glassy stone (often with a white "crust"). These come from the Chalk deposits.
The Honey Stone (Chert): Search for a translucent, yellowish-brown stone. These are derived from the Upper Greensand.
The Cliff Crumble: Find a piece of soft, red sandstone or mudstone that has recently fallen from the cliffs.

Part 2: Measuring the "Great Beach" Power

Your article notes that shingle ridges form where wave action is forceful enough to bring sediment ashore. Learners can "measure" this energy by looking at Sediment Sorting:

Top of the Ridge: Pick up 10 random stones from the very top of the shingle ridge (the "storm beach"). Measure their average size.
The Water’s Edge: Pick up 10 random stones where the waves are currently hitting the shore.
The Comparison: Usually, larger stones are thrown higher up the beach by powerful storm waves, while smaller sand and gravel stay near the water.
- Question: Does the size of the stones change as you move away from the sea? What does this tell you about the power of the waves?

Part 3: Human vs. Nature Observation

Walk to the River Sid outlet.

The River's Path: Observe the river mouth. Can you see how the shingle ridge (the "Great Beach") tries to block the river, pushing it eastward?
The Human Defences: Look at the concrete defences and the offshore breakwaters.
- Question: Can you see any "vegetated shingle" (plants growing in the stones)? Your article mentions these are rare due to human pressure. Where might they have a better chance to grow?

Part 4: Reflection

If the 'Great Beach' formed 6,000 years ago without human help , do you think our modern sea defences are helping the beach stay healthy, or are they interrupting its natural 'dynamic' life?

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