Sea Level Change Flashcards
What are the two main causes of sea level change? Describe them briefly.
1) Eustatic = The sea level itself rising or falling.
2) Isostatic = The land rising or falling relative to the sea.
Describe the features of Eustatic sea level change.
Occurs relatively quickly and globally.
Global warming causing thermal expansion, as well as ice melting.
Describe the features of Isostatic sea level change.
More local.
Two types:
Glacial - ice sheets on land make land sink (isostatic subsidence), when ice melts it rebounds (isostatic recovery). Happens over a longer period of time
Tectonic uplift, faster than glacial. eg Japan 2011 earthquake leading to tsunami which let 400km of coastline drop 0.6m.
What is an emergent coastline, and name 2 landforms typical of one.
= a fall in sea level exposes previously covered land.
*Relict cliff
*Raised beach
What is a submerging coastline, and name 3 landforms typical of one.
= a rise in sea level floods the coast.
- Rias
- Fjords
- Dalmatian coasts
What is a “Relict Cliff”, and how do they form?
Cliffs that are no longer being eroded and are isolated from the sea due to falling sea levels.
They can feature other “fossil features”, such as caves.
Often subject to weathering, mass movement and colonisation.
eg Isle of Arran, Scotland
What is a “Raised Beach”, and how do they form?
give an eg
Areas of former wave-cut platforms and their beaches, which were originally created when the sea was at a higher level, and is now exposed.
Often colonised by vegetation, disguising layers of sand and pebbles underneath.
eg West Coast of Scotland, up to 30m above sea level.
What is a “Ria”, and how do they form?
Drowned river valleys (including tributary valleys), with long fingers of water stretching a long way inland.
Widest and deepest near the sea.
Maintain the same long and cross profiles shape of the river they flooded.
eg Georges River, Sydney.
What is a “Fjord”, and how do they form?
Drowned glacial valleys, with a typical steep U-shaped cross-section with hanging valleys either side.
Thinnest at the mouth, where ice originally thinned and lost erosional power.
Can stretch many km inland.
Skerries may form at entrance where material was pushed to the front.
Usually in colder places, where glaciers have previously formed, eg Norway.
What is a “Dalmatian Coast”, and how do they form?
Occur when the topography of the land is such that valleys run parallel to the coast.
When they flood, elongated islands and peninsulas are produced separated from the mainland by the flooded valleys.
