Rocky vs Sandy Coastlines Aim: We must know and understand the following: What do they look like? What factors influence their formation? What is coastal erosion?

Specification content

Starter – High and low energy coastlines https://www.youtube.com/watch?v=6rG6IjJotWw High energy = Rocky Coastlines Low energy = Sandy Coastlines https://www.youtube.com/watch?v=HHcFiI8rx_g

there is HIGH ENERGY. EROSION exceeds deposition.

Sandy Coasts Along a coastline you find features created by deposition. These include beaches, spits and tombolos. These areas of deposition are LOWER ENERGY than that of rocky coastlines. Here the rate of DEPOSITION exceeds EROSION.

Geology – What is it and what influence does it have? Definition of Geology Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them. It includes the study of organisms that have inhabited our planet. An important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time. The geology of the cliff is a really important factor that influences the rates of erosion. The resistance of rock essentially determines differential rates of erosion. This in turn shapes our coastlines.

Geology – What is it and what influence does it have? The red line is an imaginary line that can be drawn to separate different types of geology. Its called the Tees –Exe Line which roughly divides the country into lowland and upland regions. To the south and east of this line, the landscape, whilst not always flat is certainly lower and is characterised by flat-lying or gently tilted or folded sedimentary rocks. North and west of this line are the older, generally harder rocks including igneous and metamorphic rocks and the Palaeozoic and Precambrian sandstones and limestones which usually stand out as upland areas.

Coastal processes http://thebritishgeographer.weebly.com/coastal-processes.html https://www.youtube.com/watch?v=zUh3WeilFN4 How does coastal erosion occur? occurs due to wave and current activity, high winds making larger waves, action of high tides. Resistance to erosion and hardness of rocks. Sea levels rise and storms increase in frequency and severity, coastal erosion can increase. Coastal erosion is a mostly natural process; however, man-made structures such as piers and harbours can contribute to erosion due to restructuring of the natural environment. Take a look at some images of dramatic coastlines which have been shaped by coastal erosion!

Hangman Cliffs, Devon 318m above sea level

Hangman Cliffs, Devon 318m above sea level

Boulby Cliffs, N Yorkshire 203m above sea level

https://www.youtube.com/watch?v=ht6_tgYt0lc Boulby Cliffs You don’t have to watch every second of this to get the gist! But please take a mental note of: The height and steepness of the cliffs The rock type – hard, soft geology The backshore, foreshore, nearshore and offshore areas The shape of the coastline

Conachair Cliffs, Hirta, Outer Hebrides 427m above sea level

Weathering Weathering Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material. There are three types of weathering, physical, chemical and biological. How is erosion different to weathering? Erosion is the process by which soil and rock particles are worn away and moved elsewhere by wind, water or ice. Weathering involves no moving agent of transport.

Weathering and Erosion are not the same! Highlight the definition of weathering at the top of the next page and make sure you read the Geofactsheet for homework! :-)   Hydraulic action. Air becomes trapped in joints and cracks in the cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion. Abrasion. Bits of rock and sand in waves are flung against the cliff face. Over time they grind down cliff surfaces like sandpaper. Attrition. Waves smash rocks and pebbles on the shore into each other, and they break and become smaller and smoother. Solution. Weak acids contained in sea water will dissolve some types of rock such as chalk or limestone.

Definitions Erosion Transportation Rocky coastlines and sandy coastlines are different due to these processes below: Definitions Erosion Transportation

Rocky coastlines and sandy coastlines are different due to these processes below: Definitions Erosion = the wearing away of the land by forces such as water(rivers and marine), wind, and ice. Transportation =The four different river transport processes. Solution - minerals are dissolved in the water and carried along in solution. Suspension - fine light material is carried along in the water. Saltation - small pebbles and stones are bounced along the river bed. Deposition= is when eroded material is dropped by constructive waves(coastal geography). It happens because wave have less energy.

Coastal Erosion occurs due to many PHYSICAL PROCESSES that are constantly in action. Erosion creates many different LANDFORMS which we will learn about later in the topic. *****We will come back to this flow diagram later in the topic and discuss in more detail   Add these key words to the flow diagram on the next page. Use different colours to make it stand out   HIGH ENERGY LOW ENERGY ROCKY COASTS SANDY COASTS POWERFUL WAVES GENTLE WAVES LESS EROSION MORE EROSION MORE DEPOSITION LESS DEPOSITION HEADLANDS BEACHES

Coastal Erosion occurs due to many PHYSICAL PROCESSES that are constantly in action. Erosion creates many different LANDFORMS which we will learn about later in the topic. *****We will come back to this flow diagram later in the topic and discuss in more detail   HEADLANDS ROCKY COASTS LESS DEPOSITION SANDY COASTS LOW ENERGY   GENTLE WAVES LESS EROSION BEACHES POWERFUL WAVES MORE EROSION MORE DEPOSITION

You must know your ROCK TYPES  Before we can discuss the influence of GEOLOGY any further we must know and understand the three main rock types. Complete the card sort on ROCK TYPES and create a spider diagram.

Rock strata structures The geology of a rock affects how its resists breakdown(weathering) and how fast it wears away(erosion) Another important factor is Rock Structure or Geological Structure This can determine how fast rocks at the coastline are shaped. The shape of the coast is called coastal morphology https://www.youtube.com/watch?v=SoOb4fg7cqk Highlight the images within your booklet p29 using the next PPT slide Then use pages 114 and 115 to define each key term

Bedding planes, Dip of rocks, faults and joints/fissures

Fissures Folding Rock layers laid down horizontally Rock layer/unit C Is the oldest. Rock layers are buckled Upwards into an ANTICLINE due to a tectonic event. Over millions of years the land surface undergoes weathering and erosion to produce an eroded uneven surface, exposing the repeated layers.

Understanding ‘Dip of rocks, faults, joints and fissures’ Add notes from textbook p114 and 115 into booklet p30

Horizontal layered sedimentary rock -Limestone Resistant Headland- Dolerite(Hard Igneous Rock) Anticline exposed on the foreshore composed of limestone.

Same location as previous photo but from a different angle Resistant Headland- Dolerite(Hard Igneous Rock) Same location as previous photo but from a different angle Anticline and syncline exposed on the foreshore composed of limestone.

Lulworth Crumple Stair Hole

Geology and Erosion Explain how rocks and their resistance to erosion influence the height and shape of our coastlines (read left hand side of page 112 to help you)

Marine and Sub aerial cliff profiles Make sure you include what is/define MARINE EROSION and SUB- AERIAL EROSION (p111 & top of p112) Draw each cross profile from the textbook P111

Coastal Plains Kent, SE England They form in two ways: Fall in sea level which exposes the sea bed/ shallow continental shelf, e.g Atlantic coastal plain USA Deposition of sediment brought down by rivers which gradually build out to sea, causing a delta. This process is called coastal accretion(creation of new land which can be stabilised by vegetation) Many coastal plains are in equilibrium(in balance) as rivers bring sediment, plus sediment brought in from offshore zones and longshore drift At the same time is balanced by erosion from marine action Kent, SE England These are low lying areas, low relief and close to the coastline. Low energy, lacking large powerful waves(except in rare occasions such as storms or hurricanes) Typical areas are wetlands and salt marshes just above sea level. ****Dynamic Equilibrium = balanced system in INPUTS & OUTPUTS. If the natural system is upset by outside influences the internal system is upset. Feedback adjusts to the change and equilibrium is restored.

The formation of HEADLANDS and BAYS will be part of the focus for the next lesson HOMEWORK – Complete the questions on p34 of the booklet using these images above

Do these images suggest high energy or low energy Do these images suggest high energy or low energy? The energy of the waves at the coastline is another important factor influencing the coastline shape. What is the energy level at a coastline which has headlands and bays? Explain your answer.   They suggest high energy at rocky coastlines. Why? The evidence is from the landforms caused by erosion such as headlands, natural arches, stacks, stumps. The rocks here resist erosion and therefore these features are the result. There is minimal deposition at these locations and very often the beaches are thin or narrow. Waves at high energy coastlines are usually destructive and take material away rather than build it up. At bay locations it is the complete opposite. These are areas of deposition, lower energy and constructive waves which build up beach sediments providing large, wide sandy beaches. **We will look into energy levels and wave types later on in the topic.