Coastal and Glacial Case Studies

AQA A-Level Geography requires you to use detailed case studies to support your arguments in examination answers. This lesson consolidates the key case studies for coastal and glacial geomorphology, providing the depth of knowledge needed for top-band responses.

---

Case Study 1: The Holderness Coast — Rapid Coastal Erosion

The Holderness coast is the most rapidly eroding coastline in Europe and is essential knowledge for AQA A-Level Geography.

Location and Context

• Stretches 61 km from Flamborough Head (chalk headland) to Spurn Head (shingle spit)
• Located on the east coast of Yorkshire within Sediment Cell 1
• The cliffs are composed of glacial till (boulder clay) deposited during the Devensian glaciation (c. 115,000–11,700 years ago)

Rates and Scale of Erosion

• Average cliff retreat: 1.8 m per year (some sections exceed 5 m in individual storm events)
• Since Roman times: approximately 4 km of land lost and over 30 villages destroyed
• Approximately 3.4 million m³ of sediment eroded annually
• The village of Skipsea has lost its castle site to the sea; Owthorne has retreated over 1.5 km since mediaeval times

Causes of Rapid Erosion

1. Weak geology — glacial till is unconsolidated, crumbles easily and is rapidly eroded by hydraulic action
2. Narrow beaches — the till produces mainly fine sediment (silt, clay) that is transported offshore rather than forming a protective beach
3. High wave energy — exposed to North Sea waves with a fetch of up to 800 km from the north-east
4. Sub-aerial processes — rainfall saturates the clay, triggering rotational slumps and mudflows. Freeze-thaw in winter adds to cliff destabilisation
5. Longshore drift — removes approximately 500,000 m³ of sediment southward each year, preventing beach accumulation
6. Limited foreshore protection — no durable wave-cut platform develops in soft till
7. Rising sea levels — estimated at 2–3 mm per year in this area, increasing wave attack on cliff bases

Management Approaches

Settlement	Strategy	Details	Outcome
Bridlington	Hold the Line	Sea wall, groynes, rock armour	Town protected; key economic centre
Hornsea	Hold the Line	Concrete sea wall, timber groynes	Beach maintained; downdrift erosion accelerated
Mappleton	Hold the Line	Two rock groynes, rock armour (1991, £2m)	Village protected; erosion at Great Cowden increased from 2.5 to 4 m/year
Withernsea	Hold the Line	Sea wall, groynes	Settlement protected but terminal groyne effect
Easington Gas Terminal	Hold the Line	Rock armour revetment	Critical infrastructure protected
Between settlements	No Active Intervention	No defences	Agricultural land lost; compensation issues
Spurn Head	Managed Retreat	Road abandoned after 2013 storm surge	Natural processes allowed

Key Evaluation Points

• Hard engineering at individual settlements disrupts longshore drift, creating sediment starvation downdrift
• The SMP2 for Holderness adopts "No Active Intervention" for most of the coast — only major settlements are defended
• The estimated cost of defending the entire coast: over £500 million — far exceeding the value of land at risk
• Raises significant social justice and ethical issues: rural communities and farmsteads receive no protection
• The sediment eroded from Holderness feeds beaches at Spurn Head and contributes to salt marsh development in the Humber Estuary — protecting Holderness would starve these systems

---

Case Study 2: The Dorset Jurassic Coast — World Heritage Coastline

The Dorset and East Devon coast was designated a UNESCO World Heritage Site in 2001, recognised for its outstanding geological interest.

Geological Significance

• The coastline spans 154 km from Exmouth (Devon) to Studland Bay (Dorset)
• Exposes rocks from three geological periods spanning 185 million years: Triassic (252–201 Ma), Jurassic (201–145 Ma) and Cretaceous (145–66 Ma)
• Walking from west to east is literally "walking through time"

Key Landforms

Lulworth Cove:

• A classic example of a cove formed on a concordant coast
• Resistant Portland limestone forms the narrow entrance (breached by the sea along a fault)
• Behind this, softer Wealden clays and Greensand have been eroded into a circular bay
• Chalk forms the back wall of the cove
• Demonstrates differential erosion and concordant coastal structure

Durdle Door:

• A natural limestone arch formed in Portland limestone
• Waves exploited a weakness (fault or joint) in the headland
• Hydraulic action and abrasion eroded a cave through the headland, creating the arch
• The arch will eventually collapse to form a stack

Old Harry Rocks:

• Chalk stacks and stumps at the eastern end of the Jurassic Coast (Studland)
• Old Harry is a stack; Old Harry's Wife collapsed to a stump in 1896
• Demonstrates the headland erosion sequence: cave → arch → stack → stump
• The chalk headland of Ballard Down continues to retreat

Chesil Beach:

• A tombolo connecting the Isle of Portland to the mainland
• 28 km long, up to 14 m high and 200 m wide
• Composed of flint and chert pebbles that show longshore grading — pebble size increases from west (pea-sized at West Bay) to east (fist-sized at Portland)
• The mechanism of this grading remains debated: wave energy, longshore drift, and storm sorting all contribute

Management Challenges

• Balancing geological conservation (maintaining natural processes, allowing erosion) with protecting settlements (Lyme Regis, West Bay, Swanage)
• Lyme Regis has invested over £30 million in coastal defences since 1995, including sea walls, rock armour, and cliff stabilisation
• The World Heritage Site status restricts the type of defences that can be built — natural appearance must be maintained
• Tourism generates approximately £100 million per year for the local economy

---

Case Study 3: Svalbard Glaciers — Arctic Glaciation

Svalbard is a Norwegian archipelago in the Arctic Ocean (74–81°N) with approximately 57% glacier cover.

Glacial Characteristics

• Over 2,100 individual glaciers cover approximately 34,000 km²
• Most glaciers are polythermal — cold at the surface and margins but warm-based in the interior
• Many are tidewater glaciers that calve icebergs into the sea
• The Equilibrium Line Altitude (ELA) varies from 200 m (in the north) to 700 m (in the south)

Mass Balance Trends

• Most Svalbard glaciers have shown negative mass balance since the 1960s
• Average mass loss: approximately −0.4 m water equivalent per year
• Some glaciers have retreated by several kilometres since the Little Ice Age maximum (c. 1900)
• The rate of retreat has accelerated since the 1990s due to Arctic amplification of global warming
• Arctic temperatures have risen at approximately twice the global average rate

Surging Glaciers

Svalbard contains a high proportion of surge-type glaciers (estimated 30–90% of all glaciers):

• Surges occur with a periodicity of approximately 50–500 years
• During a surge, velocity increases by a factor of 10–100
• Example: Tunabreen glacier surged in 2003–2005, advancing approximately 2 km
• Example: Nathorstbreen surged in 2009, one of the largest surges recorded in Svalbard

Significance

• Svalbard glaciers serve as indicators of Arctic climate change
• Meltwater from Svalbard contributes to global sea-level rise (estimated 0.06 mm/year)
• Changing glacial conditions affect Arctic ecosystems, including polar bear habitat
• The Ny-Ålesund research station hosts scientists from over 10 countries monitoring glacial and climate change

---