Geography coasts

Discordant coastline can also be referred to as?

atlantic coastlines

Concordant coastline can become what types of coastlines?

Haff and Dalmatian coasts

Example of a concordant coastline in UK

Lulworth cove on the Jurassic coast

Harder rock in Lulworth cove

Portland limestone

Softer rock in Lulworth cove

Wealden clay

How was the Dalmatian coast in Croatia formed

through tectonic forces and sea level rise

(that caused the submergence of land and the formation of a series of islands and coastal inlets.)

(folding of the plate caused anticlines and syclines (when it folds the land upwards and downwards, respectively —— to ~~~ the up hump is anticline and down dip is sycline)

on the adriatic sea

from the collision of the African and eurasian plates 50 million years ago

where is a haff coastline?

southern baltic coast

deposition produces unconsolidated (loosely arranged not cemented together like sand etc) geological structures parallel to the coastline

Nerman Haff - from Russia to Lithuania

(just a spit turning into a bar on a large scale really)

what type of coastline is the Jurassic coast?

East = discordant

south = concordant

Name coastal erosion processes

1. Hydraulic action

2. Abrasion

3. Attrition

4. Corrasion

Name the transportational processes

1. Traction (rolling rocks along the bottom)

2. Saltation (skipping rocks along bottom)

3. Suspension

4. Solution

strata

layers of rock also known as beds

bedding planes

horizontal cracks/lines between the different strata

(surface that separates one strata and another)

created by the pauses in rock formation

joints

vertical cracks in the rock caused by tectonic movement or contraction

Folds

the result of pressure during tectonic movement causing the rock strata to fold

Faults

the result of stress or pressure on the rock causing to fracture

Dip

The angle of the rock strata

Sub-aerial processes

• weathering

  • mechanical (physical)

  • chemical

  • biological

• mass movement

  • sliding (mudslide or landslide)

  • slumping

  • rockfall

Mechanical (physical) weathering examples

• Thermal expansion(heating and cooling of the rock in general)

• frost weathering/wedging (water seeps into cracks then expands when it turns into ice over night)

• Salt weathering. (salt water gets in rock, water evaporates leaving salt crystals behind (accumulates adding more pressure))

• exfoliation (curved plates of rock are stripped from rock below)

By how much does water expand when frozen/turned to ice?

by 10%

Chemical weathering

• bodily fluids from animals (feces and urine)

• solution/carbonation (slightly acidic carbonic rain it reacts with the calcium carbonate - affects rocks like limestone and chalk)

• Oxidation (when rocks are broken down by oxygen and water.)

• Hydrolisis (chemical breakdown of a substance when combined with water)

Biological weathering examples

• animals burrowing in the ground

• Plant roots weakening the rock

• humans eroding it by walking all over it

mass movement

when rocks and loose material shift down slopes. This happens when gravity overcomes the force supporting the material.

Where permeable rock over lies impermeable rock, the permeable rock is vulnerable to mass movement because the additional weight and lubrication the water creates leads to instability

Difference between sliding, slumping and rockfall

• Slides - rock moves in a straight line

  

• Slumps are when material moves down a slope with a rotation. (cliff gets saturated with water and base is eroding (maybe wave cut notch)and slumps

• Rock falls are when material breaks apart because of erosion and weathering and then rolls down a slope.

Wave refraction and how it affects the coastline

waves bend as they hit the coastline at an angle, causing uneven distribution of energy and significantly influencing coastal shaping through erosion and deposition

How can mineral composition affect erosion?

Some minerals are more reactive than others which affects the rate of chemical weathering

Examples:

• Quartz (inert) not reactive so chemical erosion is slower

• Calcite is very reactive so erodes much quicker

How are sedimentary rocks formed?

formed from compaction and cementation of sediment called lithification

Examples of sedimentary rock

shales, sandstone and limestone

Properties of sedimentary rocks

• erode and weather more rapidly

• form in layers

• have weak bedding planes

• they are clastic

  • meaning they are made of clasts (sediment particles)

• heavily jointed

• often have many bedding planes and fractures

How are metamorphic rocks formed?

Sedimentary and igneous rocks are altered through heat and pressure but do not melt in the process

Examples of metamorphic rocks

slate and marble

Properties of metamorphic rocks

• crystalline structure

• often folded and faulted

• more resistant the sedimentary

• crystals have parallel arrangement (foliation) which means they are weaker than igneous

How are igneous rocks formed

molten rock from volcanoes cools and hardens

Examples of igneous rocks

granite and basalt

properties of igneous rocks

• most resistant

• can be categorized into 2 types

  • intrusive - form within the ground, cool slowly and have large course crystals

  • extrusive - form on the earths surface, cools quickly, forms smaller crystals

• has interlocking crystals

  • making it harder than metamorphic

• fewer joints and weaknesses than other rocks

what is differential erosion?

changing/differing rates of erosion along a coastline

the whole coastline doesn’t erode at the same rate

• headlands and bays are an example

• bay erodes quicker than the headland

How can differential erosion affect coasts lines?

• leads to headlands and bays on discordant coastlines

• alternating strata can create a cliff profile where they more resistant rock juts out

• alternating permeability

  • permeable is on the top can be at risk of mass movement because of added weight and lubrication

role of vegetation in coastal stability

• plant roots bind sand/soil together reducing the impact of erosion

• reduces wind speeds (which reduces erosion)

• dead plant life left on sand can eventually lead to the formation of soil

why is vegetation often sparse in coastal environments?

• saline water

• evaporation of water causes increase in salinity

• high wind speeds

• lack of shade

• lack of nutrients

• “free draining sediment” - water is not retained

what are pioneer species?

the first plants to grow in the harsh coastal conditions, paving the way for other plants which are less able to survive in these conditions

• help stabilize sediment

• add organic matter

• increase shade

• trap more sediment

what are common pioneer species?

marram grass, sea rocket, and glassworts

What is dynamic equilibrium in coasts

balance between inputs and outputs of energy and material

also be thought of as longer term changes such as sea level - affects the balances

you could factor in more local changes such as low and high tide, weather conditions vary wave energy etc

rate of sea level rise according to NASA and satellite technology

3.4 mm a year

How does dip of strata affect erosion?

Horizontal -

• near perfect vertical cliff profile

• notches reflecting weathering

• small scale mass movement of strata that are jointed or more easily eroded

High angle seaward dip \\~

• sloping low angled profile

• vulnerable to rock slides

Low angle seaward dip |\~

• steep profile

• may create overhanging rock

• frequent small scale mass movement

• major cliff collapse when overhanging is unsustainable from undercutting

landward dip

• steep profile

• gravity pulls loosened blocks into place

• very stable

• few rockfalls

Fancy name for plant succession in a sandy environment

psammosere

Fancy words to describe plants that colonize sand dunes

xerophytic (can withstand dry/arid and sandy conditions)

halophytic (can withstand high salinity)

Maximum height of a embryo dune

1m

fore dunes

• embryo dunes in front of it protect from winds

• allows other species to grow like marram grass

• the grass then stabilizes the dune with its root system

• the organic matter from the plants make it more hospitable for future plants

• micro climate forms in dune slack (dip between dunes)

  • “ small-scale variation in weather conditions, like temperature or wind”

Maximum height for fore dunes

5m

yellow dunes

• initially yellow (sand) but slowly darken as organic material is added to soil

• marram still dominates vegetation but more delicate flowers and bugs can be found in the dune slacks around it

• 20% of the dune is exposed

  • in earlier stages 80% of it is exposed so significant difference in coverage

Maximum height of a yellow dune

8m

grey dunes

• more stable

• good range of biodiversity

• only 10% of sand exposed

• soil acidity increases (good thing as salt is alkaline) and water content due to humus (type of good soil from decomposed organisms) being added

• shrubs and bushes appear eg gorse

Height of grey dune

8-10m

mature dunes

• oldest and most stable

• several hundred meters from the shoreline

• soil can support a variety of flora eg oak trees

• climax vegetation and climax community stage

  • the final, relatively stable stage of ecological succession in a particular environment