Caves, Arches, Stacks, and Stumps

These coastal features form through a progressive erosion process:

1. Caves: Hydraulic action, abrasion, and solution erode lines of weakness in a headland, forming caves.
2. Arches: Caves deepen and widen on both sides of the headland until the sea cuts through, forming an arch.
3. Stacks: The rock at the top of the arch becomes unsupported and eventually collapses, forming a stack.
4. Stumps: Continued erosion of the stack leads to its collapse, leaving a stump.

Vocabulary: A stack in coastal geography is a tall, isolated rock formation created by wave erosion.

Example: Old Harry Rocks on the Jurassic Coast is a famous example of stacks formed through this process.

Highlight: Understanding the formation of caves, arches, stacks and stumps is essential for National 5 Geography students studying coastal landforms.

Spits and Bars

Spits are formed by longshore drift:

1. Sediment is carried along the coast by longshore drift.
2. When there's a change in coastline shape, a long, thin ridge of material is deposited, forming a spit.
3. A hooked end can form if there's a change in wind direction.
4. The water behind a spit is sheltered, leading to the formation of salt marshes and mud flats.

Bars:

• Sometimes a spit can grow across a bay, joining two headlands.
• This is known as a bar.
• Bars can trap shallow lakes behind them, called lagoons.

Definition: A spit in coastal geography is a long, narrow accumulation of sand or shingle extending from the land into the sea.

Example: Spurn Point in East Yorkshire is a classic example of a spit formed by longshore drift.

Highlight: The formation of spits and bars is an important topic in BBC Bitesize Nat 5 Geography coasts curriculum.