distinctive landscapes - JURASSIC COAST case study focus

Coastal landscape

formed by sea processes

River landscape

formed by fluvial processes (rivers and streams - erosion, transportation and deposition)

Glacial/mountain landscapes

formed by ice and erosion

Desert/arid landscapes

formed by wind/weathering

How geology shapes landscapes

hard vs soft rock, rock type/structure

How climate shapes landscapes

rainfall, temperature, storms

How human activity shapes landscapes

urbanisation, agriculture, tourism

How geomorphic processes shape landscapes

erosion, transport, deposition

Weathering

breakdown of rocks in their original place

Mechanical weathering

freeze-thaw

Chemical weathering

solution

Biological weather

roots

Mass movement

downhill movement of material (rockfall/landslide/slumping)

Erosion

wearing away of land

Hydraulic action

force of moving water dislodges rock particles by forcing air and water into cracks, the pressure causing the rock to break apart

Abrasion

when pebbles grind along the rock platform, smoothing it down

Attrition

rocks and sediment carried by water hit each other, until they are broken down into smaller/smoother/rounder pieces, turning large rocks -> sand/silt

Solution

where water (often slightly acidic) dissolves minerals from soluble rocks (eg limestone and chalk), carrying them away invisibly within the water flow

Transportation

movement of sediment

Traction

large rocks are dragged along the floor, as they are too heavy to be lifted

Saltation

bouncing/skipping movement of loose particles, where they are lifted then dropped again, in a series of short hops

Suspension

where light particles are carried within the flow of a river or wind, staying mixed in the water, instead of settling at the bottom

Concordant coastline

rock layers parallel to coastline, same rock along length of coast, like Lulworth cove

Discordant coastline

forms headlines and bays, alternating hard and soft rock perpendicular to coastline

Headland

narrow, rocky point of land that juts out into the sea, erodes slower than land next to it (more resistant rock, eg chalk or granite)

Bay

wide, curved inlet of the sea, typically in between 2 headlands, erodes faster than the land next to it (less resistant rock, eg clay or sand)

Stack

isolated, tall column of rock standing in the sea (separate from the mainland), temporary erosional landform, when the top of an arch collapses

Stump

final, low-lying eroded remnant of a collapsed sea stack, often only visible at low tide

Arch

natural, arch-shaped rock formation created when a cave erodes through a headland, creating an opening or passage

Wave-cut platform

flat, gently sloping rocky ledge that extends out from the base of a sea cliff, formed as waves erode the cliff's bottom, creating a notch that causes the cliff to collapse and retreat inland, leaving the platform behind

Cave

natural underground hollow or passage, within a rock, typically formed by the processes of erosion (like wave action) or chemical weathering (dissolution)

Longshore drift

zigzag movement of sand and pebbles along a coastline, caused by waves hitting the short at an angle due to prevailing winds, pushing material up (swash), then gravity pulling it straight back down (backwash), moving sediment sideways down the beach

Spit

long, narrow accumulation of sand or shingle that extends from the mainland into the sea, depositional landform (created by dropping off of sediment not erosion)

Tombolo

coastal depositional landform, specifically a ridge of sand or shingle, that connects and offshore island to a mainland/other island

Hard engineering

building large artificial structures to directly absorb wave energy, preventing erosion and flooding

Hard engineering examples

sea walls, groynes, rock armour

Hard engineering pros

strong protection

Hard engineering cons

expensive, unnatural/unesthetic, shifts erosion problems down the coast

Soft engineering

using natural, less intrusive methods to protect costs by working with nature

Soft engineering examples

beach nourishment/restoration, dune regeneration

Soft engineering pros

cheaper, looks natural, sustainable, attractive

Soft engineering cons

less effective long-term, needs repeating, might lose land (managed retreat)

Location

south coast of England, Dorset and East Devon

Length

95 miles (153 km)

Site of what

UNESCO world heritage site

Headlands and bays cause JC

differential erosion

Headlands and bays details JC

hard rock (chalk) forms headlands, soft rock (clay) forms bays

Headland and bay example JC

Lulworth cove (Bay) and Durdle Door (headland)

Caves, arches, stacks, stumps causes JC

erosion

Caves, arches, stacks, stumps details JC

hydraulic action and abrasion enlarge cracks -> caves -> arches -> stacks -> stumps

Caves, arches, stacks, stumps example JC

Durdle door (arch), Old Harry Rocks (stack/stump)

Wave-cut platform cause JC

erosion and weathering

Wave-cut platform details JC

cliff retreats due to wave action -> flat platform exposed at low tide

Wave-cut platform example JC

Stair hole

Cliffs cause JC

erosion and mass movement

Cliffs details JC

hydraulic action and weathering cause rockfall and slumping

Cliffs example JC

Kimmeridge Bay cliffs

Beaches cause JC - deposition

Beaches details JC

material transported by longshore drift deposited in sheltered areas

Beaches example JC

Chesil beach (shingle beach / tombolo)

Spits/tombolos cause JC

deposition and longshore drift

Spits/tombolos details JC

shingle and sand deposited by longshore drift

Spits/tombolos example JC

Chesil beach (tombolo connecting Isle of Portland)

Distinctive rocks JC

limestone, chalk, clay sandstone -> differential erosion

Importance of tourism and human interaction

important for recreation and fossil hunting, needs sustainable management