Aerial photograph of Spurn Point curving across the Humber estuary entrance.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Headland: 1 scene unit = 10 m. common distances.

Inspect the cave from the seaward side, then compare arch, stack and stump. Openings are cut into a solid rock body; the cave retains a back wall.

How to read these results

No erosion or growth rate is calculated. Rock structure, waves, tides and sediment supply control real coasts.

Coasts

Explain how coastal erosion forms caves, arches and stacks, and how longshore drift and groynes change the movement of beach sediment.

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Why it happens

Waves erode rock, transport sediment and deposit it along the coast. The resulting landforms depend on rock structure, wave direction, sediment supply and the balance of material entering and leaving a coastal section.

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Spurn Point, England, photographed in 2024. Longshore transport supplies a spit at the Humber estuary.

Try a comparison

Select Beach transport and Groyne, or compare the attached spit.

Reading the result

The scene demonstrates selected coastal processes; a real shoreline’s response also depends on its wider sediment budget.

A common misunderstanding

Groynes create new beach sediment without affecting nearby coasts.

Groynes interrupt alongshore sediment movement and can retain material on one side. They redistribute an existing supply rather than create it, potentially reducing delivery farther along the coast. Their effects therefore need to be considered within the wider sediment budget.

Cases

Exam language

Constructive wave

A classroom description of waves that tend to build a beach because swash carries more sediment landward than backwash removes. Whether a beach actually grows also depends on sediment supply, slope and changing conditions over the whole wave cycle.

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Wave breaking at Porto Covo, Portugal. Whether waves build or erode this beach depends on the balance of swash, backwash and sediment transport over time; a single breaking crest cannot establish that balance.

Destructive wave

A teaching description for waves that tend to remove sediment from a beach, with strong backwash relative to swash. Net change also depends on sediment and wave conditions.

Longshore drift

The net movement of beach sediment along a coast as oblique waves drive swash up the beach and gravity returns backwash downslope. Direction depends on wave approach. Structures that interrupt the supply can change beaches farther along the coast.

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Spurn Point, England, photographed in 2024. Longshore transport supplies a spit at the Humber estuary.

Spit

An elongated deposit of sand or shingle attached to land at one end and extending into water, commonly built by longshore sediment transport.

Stack

An isolated pillar of coastal rock left by erosion and cliff retreat, sometimes after the collapse of a sea arch. Old Harry is chalk; Durdle Door is an arch in limestone.

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Hvítserkur, Iceland. This isolated coastal rock illustrates a stack, with openings cut through its base.

Stump

The low remnant of an eroded sea stack, often visible only at low tide. Wave action and weathering reduce the isolated rock over time. The cave–arch–stack–stump sequence is useful, although real coasts can follow more complicated histories.

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The Pinnacles coast, Purbeck, Dorset. Erosion leaves isolated stacks and lower remnants called stumps beside the retreating chalk cliffs.

Groyne

A structure extending across a beach to interrupt longshore sediment movement. Sand may build up on its up-drift side while the down-drift beach receives less. Its effects should be considered within the wider coastal sediment budget.

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Tallebudgera Creek, Gold Coast, in the 1980s. A groyne interrupts sediment movement along a beach and can change sediment supply farther down-drift.

Sediment budget

An accounting of sediment entering, leaving and being stored within a defined area. A beach can erode when losses exceed supply, even if deposition occurs briefly. State the boundaries and time period before comparing inputs and outputs.

Process0.40EnvironmentHeadland stageSpit extent0.60