CASE STUDIES Flashcards
Where are high energy coastlines found in the UK?
Stretches of the Atlantic-facing coast such as Cornwall or north-western Scotland.
Rate of erosion exceeds the rate of deposition.
What’s the UK’s most south-westerly peninsula?
Cornwall - it bears the brunt of the worse weather from the Atlantic therefore its rocky coastline can withstand frequent winter storms without suffering from rapid erosion.
Describe Cornwall’s geology
Like the rest of Western Britain, Cornwall consists of older resistant rocks like:
* igneous rocks e.g basalt and granite
* old compacted sedimentary rocks e.g old red sandstone
* metamorphic rocks e.g slates and schists
These rocks are all resistant to the erosive power of the sea, wind and rain
Where are low energy coastlines found in the UK?
Lincolnshire and Northumberland
Example of a coastal plain
The Wash in Norfolk
Describe the features that make The Wash a coastal plain
- 20km wide and 30km long - it is the largest estuary systemic the UK (formed by four rivers)
*Range of habitats from tidal creeks to mud flats and lagoons.
Where are low-lying sandy beaches found in the UK?
Much of the coast of eastern England e.g Bamburgh beach in Northumberland, Lincolnshire and Norfolk coasts.
Coasts that are predominantly low energy
Holderness in the East Riding of Yorkshire
Chalky cliffs
Flamborough Head (Yorkshire coast)
Example of estuary in western Britain
Camel estuary in Cornwall
Examples of sea stacks
Bedruthan Steps - Cornwall
Beach in Scotland containing depositional landforms
Luskentyre peninsula on South Harris in the Outer Hebrides, Scotland - lots of sand dunes
Rockfall in December 2015
Charmouth beach, Dorset
Attracted many fossil hunters as over 100 metres of cliff fell onto the beach and fossil were exposed.
In The Wash, how does the sediment originate?
- The main source is from cliffs eroding between West Runton and Weybourne, east of The Wash along the north Norfolk coast. These cliffs have eroded at about 1m per year for thousands of years. Because they are sandstone, 60% of sediment consists of sand.
- Some sediment comes from tidal currents, which pick up glacial deposits from the shallow sea floor.
- The erosion of the Holderness cliffs further north also provides some sediment, carried southwards in suspension.
- Sand is carried southwards in suspension.
- Four rivers also discharge into The Wash - bringing very fine sediment.
What do the Wash and the Norfolk coast form part of?
One of the eleven sediment cells around the English and Welsh coasts.
Describe cliffs eroding between West Runton and Weybourne, east of The Wash
These cliffs have retreated at about 1m per year for thousands of years.
Case study to show that no classification system in definitive
- Cornwall’s high-energy coast is mainly rocky, but also has long stretches of sand and some estuaries.
- Similarly, the low-lying coasts of eastern and southern England still have high cliffs e.g at Beachy Head in East Sussex
In 2001, UNESCO awarded “World Heritage” status to a stretch of what?
The coast of South Devon and East Dorset - known as “The Jurassic Coast”. World Heritage status comes form its unique “geological walk through time” - it demonstrates the whole Jurassic period with abundant fossils.
Stair Hole
Stair Hole - less than half a mile west of Lulworth Cove. The sea has eroded through limestone and clays to create a small cove. It’s the best place to see the Lulworth Crumple.
Example of limestone folding
Lulworth Crumple at Stair Hole - thin beds of Purbeck limestone and shale are clearly visible in the side of the cliff. These layers of rock were folded (crumpled) in response to tectonic movements about thirty million years ago, collision of African and Eurasian plates
Example of folds (limestone folding) - formed by pressure during tectonic activity which makes rocks buckle and crumple
Lulworth Crumple at Stair Hole, Dorset
Example of loose, unconsolidated material at the coast
Boulder clay of the Holderness coast
What is Cornwall’s coast mainly made up of?
Granite (1mm annual rate of recession so resistant)
Glacial till
Holderness coast, Yorkshire
1-10m annual rate of recession
Isle of Purbeck
Located in East Dorset, near Poole. Combination of different rock types on the Isle of Purbesck has led to coastal landscapes ranging from Lulworth Cove to Kimmeridge Bay (Kimmeridge Bay consiststs of less resistant clays where fossils can easily be found).
Example of concordant coast
- The eastern coast of the Adriatic Sea (near Croatia)
- Southern coast of Isle of Purbeck e.g Lulworth Cove
How did Lulworth Cove form?
Over time, the sea gradually eroded the resistant Purbeck limestone at the entrance to Lulworth Cove. Then, rapid erosion of the less-resistant clays behind the limestone led to the formation of a cove or a bay.
How did Lulworth Cove form (sheet)
- Formation began after the last ice age. A river swollen by melt water flowed overland to the sea.
- The river cut a valley and breached the Portland Stone. The rising sea flooded into the valley and started to exploit joints and weaknesses in the Purbeck Beds.
- Erosion then occurred of the soft Wealden clay, which had already been scoped out by the river.
- The cove formed as a pan-shaped inlet.
- The cove continued to enlarge, eroding through the greensand rock.
- Erosion was contained and slowed down by the semi hard chalk beds to produce the semi landlocked cove of today.
How does the rock type on Dorset’s coast vary?
Varies between resistant Purbeck limestone, which forms steep cliffs, to less-resistant clays and sands. These rock types alternate along the coast so that where a resistant rock is eventually eroded (e.g at entrance to Lulworth Cove) - allowing the sea to break through to the less-resistant rocks behind - erosion follows more quickly.
What was the erosion at Lulworth Cove helped by?
A local stream, the valley of which makes erosion inland easier.
Geology of the Isle of Purbeck
- Bagshot and tertiary beds - sand and clay - relatively unconsolidated
- Chalk - mechanically strong
- Wealden beds - mainly clay - relatively unconsolidated
- Portland and Purbeck beds - mainly limestone - strong and hard, but with regular joints
- Kimmeridge clay - relatively unconsolidated
Example of a Dalmatian coastline
The Dalmatian coast in Croatia
What are Dalmatian coasts also known as?
Pacific coasts e.g in southern Chile
Haff coasts
Southern fringes of the Baltic Sea i.e the Baltic Sea coastline of Poland e.g 𝘁𝗵𝗲 𝗩𝗶𝘀𝘁𝘂𝗹𝗮 𝗛𝗮𝗳𝗳 which is a large lagoon that has formed behind the Vistula spit
Example of discordant coast
- South-west Ireland
- Isle of Purbeck’s EASTERN coast, which runs south from Studland Bay to Durlston Head.