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Revision powerpoint for 3.1 Coastal Processes focusing on Muriwai Beach and Maori Bay by Takapuna Grammar Geography

Revision powerpoint for 3.1 Coastal Processes focusing on Muriwai Beach and Maori Bay by Takapuna Grammar Geography

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    3.1 revision 2013 3.1 revision 2013 Presentation Transcript

    • MURIWAI REVISION 3.1
    • In this session: • It will be more like a lecture because of time • I suggest you listen and understand rather than trying to make copious notes • I will make the power point available on knowledge net so you can look at it in more detail later.
    • This standard is titled: Demonstrate understanding of how interacting natural processes shape a New Zealand geographic environment
    • This standard is titled: Shape is how it was made and modified and how it is being modified now Demonstrate understanding of how interacting natural processes shape a New Zealand geographic environment
    • This standard is titled: This is plural so you need more than one process Demonstrate understanding of how interacting natural processes shape a New Zealand geographic environment
    • This standard is titled: Demonstrate understanding of how interacting natural processes shape a New Zealand geographic environment Your geographic environment is the South Muriwai Coastal Environment (SMCE)from Maori Bay to Okiritoto Stream (learn this)
    • Hence to score marks you must: • 1. Analyse not just describe (always give depth) • 2. Use 2 different processes in the paper • 3. Mention South Muriwai throughout answers
    • We will break up this revision session into: • 1. Going over content • 2. How To answer Questions • 3. What to expect with this exam.
    • Part 1: CONTENT
    • 3.1 CONTENT • Demonstrate comprehensive understanding of how interacting natural processes shape a New Zealand geographic environment involves: • • providing an insightful analysis of the interacting natural processes and how they shape the environment • • integrating comprehensive supporting case study evidence. • An insightful analysis includes an analysis of the interaction between the processes and
    • THE SIZE AND EXTENT OF THE ENVIRONMENT Okiritoto Stream what is the distance? Maori Bay
    • ITS LOCATION General: It is on the west coast of the North Island Specific: 40km NW of Auckland CBD . It lies between the Manukau and Kaipara harbours at 36°49'00"S and 174°27'00"E
    • THE CHARACTERISTICS OF THE SETTING • These can be divided into the: INPUTS Elements PROCESSES Processes OUTPUTS Features What the ‘things’ are that make up the environment The actions that occur between elements The result of the processes Eg Wave erosion Eg a stack Eg Sand
    • Lets look at these in detail: The Elements that give it specific characteristics WATER ELEMENTS LAND ELEMENTS AIR ELEMENTS Waves- Average 1.5 m, high energy due to 2,000km fetch over Tasman Relief – flat beach (0-5 degrees) while headland up to 200m Wind: Blows over 11knots 42% of time from SW. Currents – strong rips Sediment - white is quartz and feldspar (0.5mm diameter) and black titano-magnetite (0.25mm) Geology: Headland of Manukau Breccias while beach sandstone. Vegetation: dune plants like Spinifex and pingao, headland of flax, Manuka and Pohutakawa. Animals: 1,200 pairs of Gannets
    • Main Processes we study are: HIGH SCALE MIDDLE SCALE SUB-PROCESS WAVE ACTION Wave Formation Refraction Reflection Wave Transport and deposition Longshore drift Wave Erosion Hydraulic Action Corrasion Corrosion Spray-splash action Wind Transport Saltation (suspension and creep) WIND ACTION (AEOLIAN ACTION) Wind deposition NB: Any of these count as 2 different processes
    • Other processes you can mention: HIGH SCALE LOWER SCALE TECTONIC Volcanism Faulting CLIMATOLOGICAL Aerial weathering BIOLOGICAL Vegetation Growth Biochemical weathering Use these if answering about formation of features (several processes) but avoid if asked to analyse ONE process.
    • The Main Features and their characteristics are: FEATURE CHARACTERISTICS HEADLAND 400M long, cliffs 30m high and top of headland 200m. Made of resistant Manukau Breccias. Dense vegetation on top of trees and flax. STACK 30m high and 20m from headland. More eroded landward side. Gannet colony on top. Manukau Breccias. BEACH Foreshore 150m wide with small berm, flat 1-5 degrees only . Black ironsand accumulates at top. DUNES Av 8m, white sand dominates, stablised by fast growing dune plants with good root system. Plants adapted to salt and wind. PICTURE
    • Where These Features are Found:
    • These are all related: ELEMENT ONE PROCESS FEATURE ELEMENT TWO WAVES WAVE EROSION GEOLOGY STACK
    • Criteria 2: Natural processes that operate • A process is a series of actions. • Therefore you must show this in your answer • This happens first, then this and then this. • Pick high scale processes as you have more to talk about. Remember to analyse.
    • WAVE ACTION - due to strong winds, long fetch • 1. High Energy Waves form WHY • 2. Approach Muriwai environment from SW – WHY due to prevailing winds • 3.Waves bend or refract off the headland WHY waves slow down here first as hit shallow water. • 4. Energy or orthogonals concentrates on headland WHY due to the refraction of waves • 5. When hit the headland they erode HOW by hydraulic action of pressure differences, corrosion or chemical weathering or corrasion or battered by sediment in waves. Weak areas are attacked between high and low tide mark forming crevasses that get bigger. • 6. Notch develops that over time becomes a cave. As on 3 sides becomes an arch and roof weakened HOW by gravity, vegetation growth and biochemical weathering so collapses to form an isolated stack.
    • WIND ACTION • 1. Strong winds blow on shore WHY prevailing winds in SW belt. • 2. On beach they pick up sediment and move it in 3 ways suspension, saltation or creep WHY depends on size. Most at Muriwai saltated. • 3. Moves to backshore in bouncing fashion WHY light enough to be carried by wind but weight brings back to land. • 4. At backshore continues until wind strength reduced and deposition occurs instead. WHY usually occurs when reach an object or plants on dunes. Sets up zone of zero wind velocity. • 5. Over time dunes grow in size WHY As plants are buried shoots grow upwards effecting zone of zero wind.
    • Criteria 3:The distribution and formation of the natural features • Distribution refers to where they occur. • Why do dunes occur at back of beach and not on the headland? • Why does the stack occur at end of headland and not back of beach? • All the result of what the characteristics of the features are like.
    • How Features are Formed • Suggest do either the stack or dunes. • Often asks for several processes involved in the formation of the feature • Stack result of : volcanism (caused resistant rock), Tectonics (push above sea), Wave Erosion, aerial weathering and biochemical weathering above high tide level. • Dunes result of: Saltation, Aeolian deposition and Vegetation Growth
    • Criteria 4: Spatial variations in the operation of natural processes in the geographic environment • What this means: Where a process happens most and least. • You must answer by saying where it dominates, happens a lot, does not happen etc. • This is due to differences in the elements as they are not equally distributed in the environment. For Muriwai break down into 3 sub areas of Muriwai beach, Otakamiro Headland and Maori Bay.
    • MURIWAI BEACH OTAKAMIRO HEADLAND MAORI BAY Wide flat area Hilly Flat beach but small and cliffs at back Wind onshore and strong Strong onshore wind Winds confused by stack Waves less energy as orthogonals diverge Waves strong as orthogonals converge Waves also confused by shape Lots of loose (unconsolidated) sediment No loose sediment only solid rock Loose sediment on beach but more black sand As wave erosion needs converging waves and hard rock happens most on headland, a little at Maori Bay and only in storm conditions at Muriwai Beach. As saltation needs loose sediment and a wide flat area to operate this occurs most at Muriwai beach, only a little at Maori Bay and not at all at the headland.
    • Criteria 5: Temporal variations in the operation of natural processes in the geographic environment • This is similar but over time. Processes do not occur consistently but happen more at some times (when elements required are favourable) compared to other times when are sparse. • In our case the best examples relate to summer versus winter.
    • SUMMER WINTER Highs dominate in Tasman Depressions dominate in Tasman Produce gentle spiller waves and light breezes Produce plunger waves and strong winds often of storm condition. Wave Action: Gentle spiller waves have greater swash than backwash, deposit more than remove so build up beach profile. Strong plunger waves have stronger backwash than swash so remove more sediment than deposit leaving flatter profile. Taken to sand bar. Wind Action: Gentle breezes in summer mean that saltation is not as common. As a result the dunes are not replenished as much as in storm conditions in winter.
    • • Wave Erosion • 1. Building of solid wall in 80’s. No good as energy directed downwards and wall collapsed. • 2. Building of gabion cage in 90’s. Better as wave energy dissipates through spaces between rocks. However in storms so much water so a lot reflected off wall and onto the southern part of beach causing excessive erosion. Had outcome of a flatter beach at this end. • 3. Rip Rap in 2005 means more spaces for storms and extra protection. Outcome is that wave erosion is reduced. • All actions deliberate and aim to protect access to Fisherman’s rock. Now successful
    • • Wind Action • 1. Some actions accidental such as building surf club tower. Sets up zone of zero wind velocity and sand builds up against wall as wind deposition increased. This caused it to be buried. Had to be moved backwards 3 times. • 2. Also effects of farming in 1880’s and dune surfing in 1980’s. Remove protective vegetation cover so cannot stop saltation from increasing. • 3. Deliberate sand stabilisation schemes of 1931 and 1969 helped to increase wind deposition by planting first marram grass and then spinifex on dunes. First one too successful as dense vegetation so dunes collapsed. Second better allowing some saltation to continue. Outcome is stable dunes.
    • End of content • Do you feel you understand this better? • Get up and have a 1 min break.
    • Part B: How To Answer questions • They are asked in 3 ways: • 1. An Essay (diagrams may be included) • 2. A diagram only (one or a series of them) • 3. A diagram for (a) with a written component for (b)
    • Let us start with Essays
    • Rules for different grades: • Be clear what the different grades are awarded for • There are 2 sorts of mark per question • 1 refers to depth of answer • 1 refers to use of specific information
    • Let’s look at depth of answer first: • Analyse the operation of one process (forget environment here) • The waves come in and hit the headland and cause erosion • This gets an NA as does not analyse. How is erosion caused?
    • • The waves come in and refract so that they concentrate on the headland and erode it where it is weaker • This now would get an A as has some explanation/ analysis in it
    • • The waves come in and slow down off the headland first so that they refract or bend which concentrates the energy of the waves onto the headland. Sub-processes of wave erosion such as hydraulic action and corrosion then attack the rock where it is weaker and break it down. • This has some depth so gets a Merit.
    • To lift this further you need to give technical understanding • The wave velocity slows as it approaches the shoreline due to the frictional drag caused when the wave hits the bottom. This causes the wave to bend or refract and concentrates the orthgonals or wave energy on the end of the headland. Here processes such as hydraulic action (pressure differentials when air is forced into joints), corrasion (waves using sediment to batter the rock) and corrosion (chemical breakdown of the minerals in the rock by seawater) break down the resistant rock between high and low water to form a notch.
    • Then you must add specific information to this: • First time it is linked to setting is equal to an A • When 3 mentions made becomes an M • When more than 3 used throughout the answer becomes an E.
    • So if we take our Excellence example it becomes: • Waves at Muriwai have high energy due to the 2,000km fetch across the Tasman sea and average 1 ½ m in height. The wave velocity slows as it approaches the South Muriwai shoreline due to the frictional drag caused when the wave hits the bottom. This causes the wave to bend or refract and concentrates the orthgonals or wave energy on the end of Otakamiro headland. Here processes such as hydraulic action (pressure differentials when air is forced into joints), corrasion (waves using sediment to batter the rock) and corrosion (chemical breakdown of the minerals in the rock by seawater) break down the resistant Manukau Breccia rock between high and low water to form a notch.
    • What Are the other rules about essays? • 1. Read the question carefully and highlight key words • 2. Do a rough plan on the planning page and keep to it. • 3. It needs an introduction, body and conclusion • 4. You must write in full sentences. Bullet points or note form is only able to score a maximum of an A. • 5. Use space as a guide to length needed. Aim to fill this. • 6. Try to include at least one diagram even if rough and refer to it in text.
    • Learn a few short cuts: • Start with a standard paragraph that includes your 3 specifics: • South Muriwai beach is located 40km NW of Auckland CBD and extends from Okiritoto stream in the north to Maori Bay 5km south. (then restate question) • Specifics can also count in a map so include this.
    • What About Rules for Diagrams • It is important to establish if this is: • 1. A stand alone diagram question • 2. A diagram as part (a) with written part (b) • 3. A diagram within an essay
    • Part 3 : What is this years exam likely to look like?
    • Assessment Specifications • Candidates will be provided with a choice of TWO questions to answer. • Candidates will be expected to answer ONE question using both an annotated map or diagram and a related written component. • Both parts contribute toward the single grade that will be awarded.
    • • Format of the assessment • Candidates should use specific information and / or case studies to illustrate their answers • • Equipment to bring • Scientific calculator, coloured pencils, and a ruler. • Candidates should use coloured pencils in their diagrams / maps. Annotations on these diagrams / maps must be in pen. Any work done in pencil will not be eligible for reconsideration.
    • How To Answer annotated diagrams • If asked to draw a map/diagram it must have its FACKTS • You must make it specific to your environment ie Muriwai • You must annotate it to show HOW something happens.
    • Finally: • Remember to include at least 5 statistics in your answer • Make it focus on Muriwai. • Read the question twice and underline important words. • GOOD LUCK FROM US ALL!!!