Summary
Summary - Unit 1 - Dynamic Landscapes (9GEO-01) - TECTONIC HAZARDS
- Course
- Institution
A full in-depth summary of content notes following full specification for tectonic hazards (including all case studies)
[Show more]
Seller
Follow
keiraboucher
Reviews received
Content preview
Topic 2 – Coastal Landscapes and changeEnquiry Question 1: Why are coastal landscapes different and what processes causes these differences?
2.1 Key Idea: The coast, and wider littoral zone, has distinctive features and landscapes
2.1a) Parts of the littoral zone
Littoral Zone:
- The area of shoreline where land is subject to wave action
- Subdivided into offshore, nearshore, foreshore and backshore:
o Offshore: the area of deeper water beyond the point at which waves begin to break
o Nearshore: the area of shallow water beyond the low tide mark
o Foreshore: the area between high tide and low tide mark
o Backshore: the area above the high tide mark, affected by wave action only during major storm
events
Types of coastlines:
- Cliffed:
o Areas of high relief varying from a few metres to hundreds of metres in height
o Formed in areas:
Resistant geology
High energy environments
Erosion > deposition
Destructive waves
- Sandy:
o Areas of low relief with sand dunes and beaches, that are much flatter
o Formed in areas:
Less resistant geology
Low energy environments
Deposition > erosion
Contrastive waves
- Esturarine:
o Areas of low relief with salt marshes and mudflats
o Formed in areas:
Less resistant rock
Low energy environments
Deposition > erosion
In river mouths
2.1b) Classifying coasts
Short term criteria:
- Energy inputs:
o High energy:
where the water hits
, exposed to strong steady, zonal winds wit
o Low energy:
Where water flows after being absorbed
Sheltered areas from storms and swells, where beaches form
- Sediment inputs:
o Sediment is added to the coastline via deposition and is removed via erosion
o The coast receives sediment input form: waves, wind, tides, current, mass movement and
tectonic processes
o Eroding coastline = erosion > deposition, a net loss of sediment and coastline retreats
o Outbuilding coastline = deposition > erosion, a net gain of sediment and coastline advances
- Advancing/retreating:
o Coasts are classified as advancing or retreating due to long term processes
(emergent/submergent) and short term (outbuilding /eroding)
Long term criteria:
- Geology:
o Based on rock type, structure of rocks
o Used to classify coasts as cliffed, sandy or estuarine / concordant or discordant
- Sea level change:
o Can be used to classify coasts as emergent or submergent
o Caused by:
Tectonic processes: can lift sections of land up, causing local sea fall / allows land to
subside, causing local sea rise
Climate change: causes seal level to rise and fall in a 100,00-year cycle due to change in
earth’s orbit
2.1c) Rocky coasts and coastal plains
Characteristics of rocky coasts:
- Occupy about 1,000km of UK’s coastline
- Cliffs vary in heigh form high relief to low relief areas
- Found in north and west of UK
- Usually form in areas:
o Geology that is resistant to erosive forces of the sea, rain, and wind
o Lithology and structure making them erode and weather slowly.
- Form in high energy environments, where erosion > deposition
Characteristics of coastal plains (sandy and estuarine):
- Relatively flat, low relief areas adjacent to the sea
- Found in south and east of UK
- Often contain freshwater wetlands and marshes due to the poor drainage of the flat landscape
- Their littoral zones are composed of sand dunes, beaches, mud flats and salt marshes.
- Form in low energy environments, where deposition > erosion
= Weathering: The breakdown of rock in situ, and may be mechanical, biological or chemical process
,= Erosion: The breakdown of rock and its immediate transport by the eroding agent
= Mass Movement: The downslope movement of material due to the force of gravity
2.2 Key Idea: Geological structure influences the development of coastal landscapes at a variety of scales
2.2a) Concordant and discordant
Concordant (aka. Dalmatian coasts):
- Forms where rock strata or fold run parallel to the coast
- Have long narrow islands running parallel to coastline
- E.g Dalmatian Islands, Croatia
Discordant:
- Forms where strata or structure are aligned at an angle to the coastline
- Have a crenelated pattern of projecting headlands and indented bays
- E.g. Atlantic coasts, cork islands, Ireland
2.2b) Morphology
Morphology:
- The shape of landscape feature
- Influenced by geological structure
o Headlands and bays = discordant
o Dalmatian and haff = concordant
Coastal systems:
2.2c) Geological structure and cliff profiles
Definition: Example:
Joints: - Fractures in rocks created without Bantry bay:
displacement - Carboniferous Limestone is heavily jointed,
- Occur in regular patterns dividing leading to more rapid fluvial and marine
rock strata up into blocks with a erosion than in adjacent sandstones,
regular shape contributing to the formation of headland
- Jointing increases erosion rates by and bay coastal morphology.
creating fissures which marine
, erosion processes
Faults: - Major factures in rock created by Bantry bay:
tectonic forces, with displacement - A major fault runs SW-NE down the centre of
of rocks either side of the fault line the bay.
- Increase rate of erosion since zones - The Carboniferous Limestone is significantly
are faulted rock are much more weakened by faulting, allowing rapid fluvial
easily erodes erosion, and the resulting river valley was
inundated to form a ria when sea levels rose.
- Faulting also allowed more rapid marine
erosion than in unfaulted Old Red Sandstone,
contributing to headland and bay coastal
morphology.
Folds: - Bends in rocks
- Produced by sedimentary rock layers being squeezed by tectonic forces
- Folded rock is more heavily fissured and jointed, therefore eroded more easily
- Increases erosion rates by increasing angle of dip and by causing joint formation as rock is
stretched along anticline crests and compressed in syncline troughs
Dip: - The angle of inclination of the rock strata from the horizontal
- Sedimentary rocks are deposited horizontally but can be tilted by folding and faulting by
tectonic forces.
- It can have dramatic effects on cliff profiles.
Cliff profile:
- The heigh and angle of a cliff face + its features (e.g., wave-cut notches pr changes in slope angle)
Micro-features:
- Small-scale coastal features (e.g., caves and wave cut notches) which from part of a cliff profile
- They form in areas weakened by heavy jointing, which have faster rates of erosion, enlargement he
joints to form a sea cave
- The location of micro-features within cliffs and is controlled by the location of faults and strata which
have particularly high density of joints and fissures
2.3 Key Idea: Rates of coastal recession and stability depend on lithology and other factors
2.3a) Lithology
Igneous: - Formed from solidified lava or magma Granite
- Erode and weather very slowly, producing very slow rates of coastal Basalt
recession (composed of interlocking crystals, forming hard, resistant Pumice
rock, have fewer joints)
Metamorphic: - Formed by the recrystallisation of sedimentary and igneous rocks Slate
through heat and pressure Schist
- Hard and resistant (crystalline structure) Marble
- Less resistant than sedimentary as they are often faulted and folded Gneiss
Sedimentary: - Formed by the compaction and cementation of deposited material, Sandstone
or sediment Limestone
- Least resistant type of rock due to weak bedding planes, and heavily Shale
jointed
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller keiraboucher. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.66. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75057 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now