First Batch: 1.1 - 1.7 Flashcards
1.1: Littoral Zone
- The Littoral zone is the beach zone
- Consists of backshore, nearshore and offshore zones
1.1: Offshore
The area further seaward than the nearshore
1.1: Near shore
- The area from the mean high tide mark to beyond where waves break
- It includes all areas affected by currents due to proximity to land
1.1: Backshore
- The upper beach closest to land
OR - Area from mean high water mark up to a change in physiography such a sand dune or cliff
1.1: Primary Coasts
A type of coast dominated by land-based processes
e.g. Zavodovski Island
1.1: Secondary Coasts
A type of coast dominated by marine erosion/ deposition
e.g. Slapton
1.2: Constructive Wave Type (Summer)
- Low Height
- 6-8 per minute
- Uninterrupted swash, starts at nearshore
- Strong swash results in sediment berm (raised area)
1.2: Destructive Wave Type (Winter)
- High height, short wavelength
- 13-15 per minute
- Slower waves approach steep/beach
1.2: Percolation
Downward movement of water through …
- soil
- sand
- pebbles
1.2 Do shingle beaches have more percolation than sandy beaches?
Yes, they do.
This is because shingle beaches have gaps between the pebbles allowing water to penetrate and move down through the ground
1.3: Where does wave energy converge on a beach?
Converges on headlands
1.3: How does wave refraction affect a beach?
- Refraction leads to waves concentrating on a headland accelerating the rate of erosion
- This material is then deposited in the bay
1.4: What are Dalmatian Coasts?
- A type of concordant coastline
- An example of a tectonically formed submerged valley
The name is taken from Dalmatia, Croatia:
- Geology of Dalmatia is limestone
- Subsequently subjected to tectonic activity
1.4: Define strata:
Refers to rocks arranged in layers
1.4: Define Deformation:
How the strata are folded by tectonics
1.4: Define Faulting:
Fractures that occur when rock is folded
1.4: What is the role of geological structure at concordant coasts?
- Strata runs parallel to the coastline
- Rock strata may be folded into a series of anticlines and synclines
1.5: What is Isostatic sea level change?
A local change in sea level due to a change in local coastline or land height
1.5: Why does Isostatic sea level change occur?
- Heavy ice pushes land downwards
- When this ice melts, the land rebounds back
- Giving the perception that sea level is changing
1.5: Tectonic Influence on Isostatic sea level change?
- Plate convergence/ subduction causes a sudden thrust
- Which can lead to upwards/ downwards movements of the sea bed
1.5: Features of an Emergent Coast:
- Characterised by raised beaches/ relict fossil fuel cliffs
- Have moved away from marine processes
- Terrestrial processes operate instead
1.5: What is an emergent coastline?
A coastline that is advancing relative to sea level at the time
1.5: Features of a raised beach:
- Found above high-tide
- Reflects a series of stages of uplift
- Smaller particles are removed by waves, leaving rounded pebbles/ boulders
1.5: Features of Fossil Cliffs:
- Found near vertical cliffs, but inland
- Sometimes near old sea caves/ wave cut platforms
1.6: What is a Fjord?
- Submerged U-shaped valley that has been over deepened inland
- Rock lip threshold exists at the seaward entrance
1.6: What is a Fjord? (PMT)
- Long narrow inlet of sea water which is between steep mountains
- They are created when sea levels rise relative to the land, flooding coastal glacial valleys
1.6: What is a ria?
- A drowned valley that exists due to river erosion
1.6: What is a rias? (PMT)
- Narrow winding inlet which is deepest at the mouth
- Formed when sea levels rise causing coastal valleys to flood
1.6: What is Eustatic Sea level change?
Global changes to sea level
- Sea level has risen approximately 125m from the Last Glacial Maximum
- Most ice melted around 6000 years ago and sea level is now only slowly rising
1.6: How can Tectonics affect Eustatic SL change?
Faulting and folding of crust can create displacement of seabed
1.7: Describe/ Explain Eustatic Fall:
- Happens during glacial periods
- Ice sheets are formed on high-latitude land
- Evaporated water is locked up as ice
- Less water in the sea
1.7: Describe/ Explain Isostatic Fall:
- Icy sheet melt, and land surface slowly rebounds upwards:
- lifting the land surface out of the sea - sea level appears to fall
1.7: Describe/ Explain Eustatic Rise:
- Interglacial periods - ice sheets on land melt
- Melted water returns to the sea, so sea-level rises
- Global temperature also causes THERMAL EXPANSION as water particles more faster taking up move space
1.7: Describe/ Explain Isostatic Rise:
- During glacials: Land is compressed by the weight of glaciers, causing sea level to appear to rise
- During interglacials: ice melts leads to sediment being deposited in large river deltas
- This leads to increased weight and delta subsidence - sea level appears to rise
1.7: What is subsidence?
Sinking of ground/crust
