Key term
WJEC A-Level Geography 601-8455-3
Coastal Landscapes
Topic overviewThe coast as an open systemSediment sources and sediment cellsTides and coastal currentsConstructive and destructive wavesHigh energy coasts and erosional landscape systemsLow energy coasts and depositional landscape systemsFetch, wave refraction and wave energyLithology and structural geology at the coastSub-aerial weathering and mass movementMarine processes of erosionErosional landforms of rocky coastsCoastal transport and longshore driftDeposition, flocculation and sediment sortingDepositional landforms of sandy coastsSand dunes and aeolian processesEstuaries, tidal flats and salt marshesCoral reefs and mangrove coastlinesCoastal change over different timescalesCoastal processes and human activityHuman impact on coastal landscape systems
Glaciated Landscapes
Topic overviewThe glacier as an open systemClimate change and the glacier budgetGlacier movementTypes of ice mass and their distributionGlacial weathering and erosion processesMacro-scale erosional landformsGlacial transport and depositional landformsFluvioglacial landformsSuites of landforms in glacial landscapesPeriglacial processes and ground icePeriglacial action of water and windGlacial change over different timescalesGlacial environments and human activity
Tectonic Hazards
Topic overviewThe internal structure of the EarthMechanisms of plate movementDivergent and conservative plate marginsConvergent margins and subductionHot spots and the global distribution of tectonic hazardsThe hazard profile and measuring magnitudeTypes of volcano and styles of eruptionPrimary volcanic hazardsSecondary volcanic hazardsImpacts of volcanic activity at different scalesContrasting volcanic eruptionsEarthquake characteristics and seismic wavesEarthquake hazards and ground behaviourTsunami processes and impactsContrasting earthquake eventsRisk, vulnerability and human factorsMonitoring, prediction and warningMitigation, response and the hazard management cycle
Changing Places
Topic overviewWhat gives a place its characterFlows and connections that shape placesMeaning, perception and attachment to placeHow places are representedEconomic restructuring and the Clark Fisher modelDeindustrialisation and social inequalityThe service economy and its impactsThe knowledge economy and clustersRebranding rural placesManaging change in rural placesRebranding urban placesManaging change in urban placesComparing a home place with a contrasting placeHow place change affects people's lives
Water and Carbon Cycles
Topic overviewThe water cycle as a global system and mass balanceGlobal water stores and residence timesCryospheric processes and sea-level changeDrainage basin inputs, stores and outputsFlows within the drainage basinRiver regimes and their controlsStorm hydrographs and hydrograph shapeAir uplift, cloud formation and precipitationExcess runoff and floodingDeficit in the water cycle and aquifer rechargeThe global carbon cycle and its storesCarbon pathways between land and the atmosphereCarbon transfers involving the oceansCarbon stores in biomes and land-use changeChanging carbon stores in peatlandsRising atmospheric carbon and its impactsFeedback within and between the water and carbon cycles
Global Migration
Topic overviewGlobalisation and a shrinking worldClassifying and mapping migrationCauses of international economic migrationConsequences and management of economic migrationRefugee movements and internal displacementRural-urban migration in developing countriesSuperpowers and global hub citiesMigration policy and public debate in the UKManaging refugee crisesInformal settlements in developing cities
Global Governance of the Oceans
Topic overviewSupranational institutions and global governanceLaws and agreements governing the oceansStrategic value of the oceans and maritime securityShipping, cables and illicit flowsSovereignty over ocean resourcesManaging marine environmentsOcean pollution and its managementGovernance across scales: an ocean case study
EcosystemsContemporary theme
Topic overviewThe value of ecosystems to peopleThe distribution of global biomesEcosystem structure, energy flow and productivityNutrient cycling in contrasting biomesMeasuring and threatening biodiversityConserving biodiversitySuccession and local ecosystemsThe Arctic tundra biomeSustainable use of the Arctic tundra
Economic Growth and Challenge: IndiaContemporary theme
Economic Growth and Challenge: ChinaContemporary theme
Development in an African ContextContemporary theme
Energy Challenges and DilemmasContemporary theme
Weather and ClimateContemporary theme
Fieldwork and Geographical Skills
Tectonic Hazards
Mechanisms of plate movement
- 3 things to know
- AS Unit 1 and A2 Unit 4
Overview
Ridge push, slab pull and typical rate of plate movement.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Define slab pull.
Key term
Which of ridge push and slab pull is now thought to be the stronger force, and why?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Explain how convection in the mantle is thought to move the plates.
Model answer
Heat from the core and from radioactive decay warms mantle rock so that it becomes less dense and rises, spreads sideways beneath the lithosphere and drags on it, then cools and sinks again.
- 2
What is ridge push?
Model answer
Ridge push is the gravitational sliding of new oceanic lithosphere away from the elevated crest of a mid-ocean ridge as it cools, thickens and becomes denser.
- 3
Define slab pull.
Model answer
Slab pull is the force exerted when a cold, dense subducting plate sinks into the mantle under its own weight and drags the rest of the plate along behind it.
- 4
Which of ridge push and slab pull is now thought to be the stronger force, and why?
Model answer
Slab pull, because the plates with the longest subducting margins are the ones that move fastest, and a dense sinking slab exerts far more force than the gentle slope away from a ridge.
- 5
State a typical rate of plate movement.
Model answer
Most plates move at between about 2 and 10 cm per year.
- 6
How quickly is the Atlantic widening at the Mid-Atlantic Ridge?
Model answer
At roughly 2.5 cm per year, which is one of the slower spreading rates in the world.
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