Enquiry Question 1 Flashcards
Backshore
The cliff or sand dunes, plus the upper beach closest to the land.
Foreshore
The lower part of the beach which is covered twice a day at high tide; receives the most regular wave action
Nearshore
The section of the littoral zone between the low tide level and the deeper offshore water
Offshore
The section of the littoral zone that consists of deeper water in which waves maintain their shape and speed, furthest from the land.
Littoral Zone
The coastal zone - the boundary between land and sea
Berm
The shingle ridges often found towards the back of a beach
Breakers
As waves come closer to shore they break, forming a foamy, bubbly surface
Surf Zone
Zone of breaking waves
Bar
Elongated sand body created by tidal currents or waves
Lithology
The type of rock
What are the different types of coastlines?
- Cliffed coasts
- Sandy coastlines
- Estuarine coastlines
Concordant coastline
Coastline where one rock type runs parralel to a stretch of coastline
Discordant coastline
Coastline where alternating strata of differing rock types run perpendicular to the coast
Submergent coastlines are formed when:
When sea levels rise (e.g due to climate change or post glacial melt), low lying coastal plains are submerged
Rocky coasts are a result of:
They are a result from resist geology (withstand erosive forces of sea, rain and wind)
Where are rocky coasts found?
In high energy environments
Where are Coastal plain landscapes found?
They are found near areas of low relief and often in a low energy environment
Coastal plain landscapes are a result from:
Result from supply of sediment from different terrestrial and offshore sources.
Retreating coast
Erosion > deposition
Coastline accretion
Deposition > erosion causing the coast to advance
Dynamic equillibrium
Coastal processes vary but landform formation is continous and stays the same
Morphology
Features and landscapes. The result of coastal processes.
Haff coastlines are:
Where bars of sediment run parallel to the coastline, creating lagoons.
Formation of Haff coastlines:
CC
- During the last glacial period (Devensian), the sea level was about 100m lower than today as water was retained in huge ice sheets.
- Meltwater rivers on land beyond the ice front deposited thick layers of sand and gravel, creating outwash plains. The deposition produced geological structure parallel to the coastline.
- In the Holocene, 12,000 yrs ago, Interglacial constructive waves pushed the ride of sands and gravel landwards as sea levels rose.
- Sand ridges formed bars across some bays and river mouths with trapped river water- forming a lagoon behind, called Haffs.
3 examples of a Concordant coastline:
- Haff Coasts
- Dalmation Coast
- Lulworth Cove
Formation of Dalmation Coast
CC
- Two tectonic plates push towards each other, compressing the crust to create folds.
- The folds have anticlines and synclines
- Post glacial sea level rise has submerged the synclines leaving the anticlines sticking up parallel to the coast.
Formation of Lulworth Cove
CC
- It is on a landscape of alternating bands of geology that lay parallel to the coastline, horizontally organised.
- Weaknesses in the layered rock (clay) are exposed to marine processes so are targeted and broke down by erosional processes.
- The cove is formed out of the landscape after it gets behind the clay.
- It is unable to erode further due to the different type of rock behind it (chalk)
Formation of Swanage Bay
DC
- There are alternating bands of rock types (hard and soft) perpendicular to the coast.
- This is significant due to there being different levels of erosion
- The headland absorbs all the wave energy due to wave refraction
- As the wave gets more shallow, the wave experiences friction with the sea bed and breaks.
- Wave refraction occurs once headlands and bays exist because the headlands cause the wave to break due to the shallower water around them.
- Handlands absorb wave energy
- Rates of erosion are drawn towards the headlands; deposition occurs inside the bay - making a beach
2 examples of a Discordant coastline
- Swanage Bay
- West Cork, Ireland
West Cork, Ireland coastline description
- South west of the UK
- Waves are more powerful
- It faces Bantry Bay, where it experiences high wave energy due to waves travelling through the Atlantic ocean with a large fetch
Formation of West Cork, Ireland
DC
- Limestone eroded by waves but also verticle fluvial processes in the past creating a river valleyin the Bantley Bay coastline - (now inundated)
- As sea levels have risen, the river valley has been submerged - making the bay long and narrow
- Rivers eroded the softer rocks to form valleys
- Rising sea levels drowned the valleys
- Since then, marine erosion has continued to erode headlands and bays forming a Ria
Cliffed coast description
- The transition from land to sea is abrupt
- At low tide , the forshore zone is exposed as a rocky platform
- The cliffs are vertical and usually made of igneous, granite, basalt or older and compacted sedimentary rocks
Sandy coast description
- At high tide, the sandy beach is unundated, but vegetated dunes are not
- Consists of younger, weaker sedimentary rocks (e.g chalk, clay, sandstone)
- Dune vegetation stabilises the coast and prevents erosion
Estuarine coast description
- Extensive mudflats, cutting channels are exposed at low tide but inundated at high tide
- Closer to backshore, the mudflats are vegetated forming a saltmarsh
Where are estuaries found?
Estuaries are found at the mouth of a river
Definition of Dynamic Equillibrium
The balanced state of a system when inputs and outputs balance over time. If one element of a system changes because of an outside influence, the system adjusts to the change and equillibrium is regulated.
The order of the littoral zone
Backshore, Foreshore, Nearshore, Offshore
Submerged coast
A coast that is flooded by sea due to rising sea levels of subsiding level.
Strata
The different layers of rock within an area and how they relate to each other
Why are dips important in understanding cliff profiles
They impact how the geology is exposed impacting erosion
What is the bottom geology of the dips called?
Bedding planes
What is the position of the littoral zone affected by?
- Waves
- Tide
- Weather
- Seasonal storms (short term)
- Mass movement
- Climate change (long term)
- Sea levels rising
- Erosion / weathering
What does the resistance of rocks depend on?
- How reactive minerals are in the rocks when exposed to chemical weathering
- The degree to which rocks have cracks / fractures and fissures which are weaknesses exploited by weathering and erosion
- Whether rocks are clastic or crystalline - clastic rocks have higher rates of erosion
Emergent coasts
Where the coasts are rising relative to sea level (e.g due to tectonic up-life)
Submergent coasts
Are being flooded by the sea either due to rising sea levels and / or subsiding land.
Horizontal dip:
Vertical / near vertical coastline with notches reflecting strata that are more easily eroded.
Seaward dip: (high angle)
Sloping low angle profile with one rock layer facing the sea. Vulnerable to rock slides down dip slope.
Seaward dip: (low angle)
Profile may exceed 90 degrees, producing areas of overhanging rock, very vulnerable to rock falls.
Landward dip:
Steep profiles of 70-80 degrees, producing a very stable cliff with reduced rock falls.