Sealebel Flashcards
(19 cards)
What are 2 main types of sea level change
Isostatic (land level changes)
Eustatic (global sea level changes)
What is isostatic sea level change
local change in sea level caused by the rise or fall of land due to tectonic processes or ice mass changes.
What causes isostatic sea level change
- Post-glacial rebound (glacial isostatic adjustment) – Land rises after being compressed by ice sheets.
- Tectonic activity – Earthquakes and crustal movements can cause land uplift or subsidence.
- Sediment loading – Large river deltas (e.g., Mississippi) cause the land to sink under weight
Give example of area affected by isostatic sea level change.
Scotland is rising, + southern England is sinking due to post-glacial rebound.
Eustatic sea level change
global change in sea level caused by variations in the amount of water in the ocean or changes in ocean basin size.
What causes eustatic sea level change?
- Glacial melt – Ice sheets melting after ice ages add water to oceans.
- Thermal expansion – Warmer ocean temperatures cause water to expand.
- Tectonic processes – Changes in ocean basin size due to seafloor spreading or volcanic activity.
example of area affected by eustatic sea level change.
The Maldives is experiencing sea level rise due to thermal expansion and glacial melt.
How do isostatic and eustatic changes differ?
Isostatic = Local, due to land level changes.
Eustatic = Global, due to water volume changes.
What landforms are associated with isostatic sea level change?
- Raised beaches – Old wave-cut platforms now above sea level (e.g., Isle of Arran, Scotland).
- Marine terraces – Series of raised beaches due to periodic uplift.
What landforms are associated with eustatic sea level change?
- Rias – Drowned river valleys (e.g., Kingsbridge Estuary, UK).
- Fjords – Drowned glacial valleys (e.g., Sognefjord, Norway).
- Dalmatian coasts – Parallel flooded valleys (e.g., Croatia).
What are emergent landforms
Emergent landforms are created when land rises relative to sea level, exposing previously submerged features
What are submergent landforms
Submergent landforms form when sea level rises relative to land, flooding existing landscapes.
What processes lead to the formation of emergent landforms?
Isostatic rebound – Land rises after being compressed by glaciers during an ice age.
Tectonic uplift – Earthquakes or fault movements push land upwards.
What is a raised beach and how does it form?
Definition: former beach, now above sea level due to land uplift.
Formation:
1. Sea level falls or land rises.
2. Old wave-cut platform and beach are left exposed.
3. Marine erosion stops, + weathering (e.g., freeze-thaw) begins affecting exposed features.
Example: Isle of Arran, Scotland – Raised beaches formed after post-glacial isostatic rebound.
What are fossil cliffs and how do they form?
Definition: Steep cliffs that were once shaped by marine erosion but are now inland due to uplift.
Features: May include wave-cut notches, caves, arches, and stacks that are no longer being actively eroded by the sea.
Example: West Coast of Scotland – Fossil cliffs near raised beaches.
What processes lead to submergent landforms?
1.Eustatic sea level rise – Melting ice caps add water to oceans, submerging coastal land.
2.Tectonic subsidence – Land sinks due to tectonic activity.
What is a ria and how does it form?
Definition: A drowned river valley caused by rising sea levels flooding a coastal river system.
• Formation:
1. A river valley is carved out during lower sea levels.
2. Rising sea levels flood the valley, but higher land (interfluves) remains above water.
3. Creates a deep, winding estuary that extends inland.
Example: Kingsbridge Estuary, Devon, UK – A ria flooded due to post-glacial sea level rise.
What is a fjord and how does it form?
Definition: A steep-sided, deep glacial valley flooded by rising sea levels.
• Formation:
1. A glacier carves out a U-shaped valley below current sea level.
2. When the glacier melts, the valley is flooded by rising seawater.
3. Often much deeper than rias, with hanging valleys and waterfalls.
Example: Sognefjord, Norway – One of the deepest fjords in the world.
What is a Dalmatian coast and how does it form?
Definition: A series of parallel, flooded valleys that create islands and long, narrow inlets.
Formation:
1. Tectonic processes create folded valleys parallel to the coastline.
2. Rising sea levels flood lower areas, leaving higher ridges as offshore islands.
Example: Croatian Coastline (Adriatic Sea) – The Dalmatian Islands are former mountain ridges now separated by narrow flooded valleys.
