3. How do coastal landforms evolve over time as climate changes? Flashcards
(15 cards)
What is eustatic sea level change?
A global change in sea level caused by changes in the volume of water in the ocean (e.g. from melting glaciers or thermal expansion).
What is isostatic sea level change?
A local change in land level relative to the sea, caused by tectonic activity or post-glacial rebound.
What are the two types of sea level change, and how do they differ?
Eustatic: Global, caused by water volume change.
Isostatic: Local, caused by land rising or sinking.
What landforms are created by falling sea levels (emergent coastlines)?
Raised beaches: Former beaches now above sea level. (e.g West Scotland)
Marine terraces: Former wave-cut platforms now raised. (e.g Fife, SE Scotland)
Abandoned cliffs: Cliffs no longer affected by wave action. (e.g NW Scotland, King’s Cave)
How are emergent landforms modified over time?
Weathering (e.g. freeze-thaw, chemical) affects exposed features.
Mass movement shapes and degrades abandoned cliffs.
Vegetation may colonise terraces and raised beaches.
Give a named example of emergent coastal landforms.
SE Scotland, Fife — features include raised beaches and abandoned cliffs, formed after post-glacial isostatic rebound.
What landforms are created by rising sea levels (submergent coastlines)?
Rias: Drowned river valleys (e.g. Poole Harbour in South Dorset coast).
Fjords: Drowned glacial valleys (e.g. Loch Fyne, SE Scotland).
Shingle beaches: Sediment pushed onshore by rising seas. (Chesil Beach, Dorset)
How are submergent landforms modified over time?
Marine erosion deepens and widens rias and fjords.
Deposition may form mudflats and salt marshes at their heads.
Sea level rise increases flood risk in low-lying areas.
What are the predicted impacts of future sea level rise on coastal landforms?
Accelerated retreat of low-lying coasts (e.g. Nile Delta).
Submergence of existing features (e.g. salt marshes, spits).
Greater erosion of cliffs and beaches, especially where sediment supply is low.
How does sea level rise threaten the Nile Delta?
Erosion is outpacing deposition due to reduced sediment (Aswan Dam).
Rising seas risk flooding farmland and displacing communities.
Saltwater intrusion threatens agriculture and ecosystems.
How have past climate changes shaped coastal landscapes?
Cooler climates led to glaciation, falling sea levels, and creation of emergent landforms.
Warmer interglacial periods caused sea level rise and submergent features like rias and fjords.
How are emergent landforms modified under current conditions?
No longer shaped by wave action, so instead affected by freeze-thaw weathering, biological colonisation, and mass movement.
Climate warming may increase chemical weathering and plant growth.
How are submergent landforms like rias and fjords modified today?
Ongoing marine erosion can deepen channels.
Salt marshes and mudflats may form at their heads.
Human use (ports, tourism) may lead to dredging or stabilisation.
How could rising sea levels affect Sandbanks?
Threatens flooding of low-lying land and expensive properties.
May overwhelm groynes and engineered defences, reducing beach width.
More energy in storms could breach the spit or increase sediment removal.
How can coastal management adapt to climate-driven change?
Managed realignment may be used to allow natural processes (e.g. Saltmarsh development).
Beach nourishment might be increased to maintain defences.
SMPs must account for rising seas and increased storminess.
