Question | Answer |
7 key geographical concepts | (SCEPSIS) 1. Space 2. Change 3.Environment 4. Place 5. Scale 6. Interconnections 7. Sustainability |
Weathering definition | It is the physical or chemical breakdown of rocks into smaller pieces |
Physical Weathering | Physical weathering occurs when rocks are broken into smaller pieces by: 1. Temperature changes (common in deserts) 2. Freeze thaw action (common in mountains) 3. Tree and plant roots |
Chemical Weathering | Chemical weathering occurs when there is a chemical change in a rock material that causes it to break down e.g. 1. Oxidation – rocks that contain iron 2. Acid from rain |
Erosion Definition | A process that breaks down a material and then carries away the broken down products. |
Types of Erosion - Attrition | When waves cause rocks and pebbles on the shore to rub against each other and break down and become smaller and smoother. |
Types of erosion - Hydraulic Action | Waves hitting the cliffs force trapped air into cracks. When the wave breaks, the air becomes compressed, weakening the cliff and causing erosion. |
Types of Erosion - Solution | Sea water chemically dissolves the cliff. |
Types of Erosion - Abrasion (Corrasion) | Waves bring with them bits of rock and sand. These are bashed against the cliff, breaking it apart. |
Erosional features - CAVE | Occurs when waves force their way into cracks in the cliff face. The water contains sand and other materials which grind away at the rock until the cracks become a cave. |
Erosional features - ARCH | If the cave is formed in a headland (a narrow piece of land that projects from a coastline into the sea), it may break through the other side, forming an arch. |
Erosional features - STACK | The arch will become bigger, gradually until it can't support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack on the other. |
Erosional features - STUMP | When the stack is attacked at the base the same way as a wave-cut platform is formed, the structure weakens and will collapse to form a stump. |
Erosional features - HEADLAND | Formed when the sea attacks the section of the coast with alternating bands of hard and soft rock. When the bands of soft rock erode, a section of land, that is jutting out to sea, is left. |
Erosional features - BAY | Formed when the sea attacks the section of the coast with alternating bands of hard and soft rock. The areas where the soft rock have eroded away next to the headlands are called bays. |
Erosional features - WAVE-CUT PLATFORMS | When the backwash carries the rubble towards the sea, wave-cut platform is formed. |
Depositional Features - SPIT | The formation of a spit begins due to a change in direction of a coastline |
Depositional features - BARS | Are created where a spit grows across a bay, joining two headlands |
Depositional features - TOMBOLO | Are formed where a spit continues to grow outwards joining land to an offshore island |
Berms | Are built up from constructive waves and form ridges along the beach |
Formation of beaches | - Beaches are made up of loose material - Sand is continuously being deposited and eroded by waves - Beaches only form in protected areas with a good supply of sand |
Coastal protection strategies - RIP RAP WALLS | Are designed to dissipate wave energy and to trap sand. They cost $2200 per meter (sea walls) |
Coastal protection strategies - SAND DRIFT FENCING | Drift fencing is used to trap sand and consolidate a sand dune system. In a healthy natural environment vegetation would act as a sand stabiliser and dune builder as it traps wind blown sand. |
Coastal protection strategies - SEAWALLS | Seawalls are massive concrete structures emplaced along a considerable stretch of shoreline at urban beaches. It began being used in Adelaide during the 1960's. |
Coastal protection strategies - GROYNES (BREAKWATER) | Is a wall or jetty built out from a riverbank or seashore to control erosion. $500,000 or $2500 per meter. |
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