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| Frage | Antworten |
| Coastal Environment Division of zones | (Refer to page 5 of textbook) |
| Costal Environments 2 What are some types? | Cliffed Sandy Muddy Rocky |
| Factors Affecting Coastal Environments Waves How? | Wave action is the main shaping force of coastal environments. Waves form when wind blows across the surface of seas and oceans. Energy from the wind is transferred to the water and it is this wind energy that helps shape coasts when waves hit land. |
| Factors Affecting Coastal Environments 2 Tides and Sea Level Changes What are tides? How does it happen? | Tides refer to the daily alternate rise and fall in sea level. They are caused mainly by the effects of the gravitational pull of the moon and sun on the earth. Low tides are experienced between the high tides. It takes 6 hours for tides to change. |
| Factors Affecting Coastal Environments 2 Tides and Sea Level Changes 2 How do tides affect the coast? | Tides affect processes such as coastal erosion, sediment transport and sediment deposition. During high tides, waves reach parts of coasts that may not be subjected to wave action at low tides. Hence, at high tides, waves erode and transport more sediments away from larger parts of the coasts than at other times. |
| Factors Affecting Coastal Environments 2 Tides and Sea Level Changes 3 How do sea level changes affect the coast? | Changes in sea level also occur over an extended period of time. At the end of the last ice age about 10,000 years ago, temperatures rose and glaciers thawed, releasing massive volumes of water into seas and oceans. The resultant rise in sea level of up to 100 metres in some parts of the earth created new coastlines. In recent times, the rise in sea level can be attributed to climate change. |
| Factors Affecting Coastal Environments 3 Currents What is it? What causes it? | Currents are large-scale, continuous movements of water in seas and oceans. They are driven largely by prevailing winds which generally blow in one direction. |
| Factors Affecting Coastal Environments 3 Currents 2 How does it affect the shape of the coast? | Ocean currents play a very important role in distributing sediments and regulating temperatures. Currents carry large amounts of energy and shape coasts through the processes of coastal erosion, sediment transport and sediment deposition |
| Factors Affecting Coastal Environments 3 Currents 3 How does it affect the climate? | Ocean currents carry cool water away from the North and South Poles towards the Equator and warm water away from the Equator towards the Poles. In this way, ocean currents help create milder climates in coastal environments. |
| Factors Affecting Coastal Environments 4 Geology What is it? | Coastal environments are affected by their geology, which is the arrangement and composition of rock found in the area. Rocks may be arranged in layers such as in alternate layers of hard and soft rocks |
| Factors Affecting Coastal Environments 4 Geology 2 How do rock composition relate to erosion? | Rock composition determines the hardness of rocks and their resistance to erosion, which affects the rate of change along coasts. More resistant rocks such as granite and basalt will erode slower than less resistant rocks such as limestone and shale. Yet granite and basalt arre vulnerable to erosion when the joints of these rocks are attacked by waves, Erosion hence weakens the rocks. |
| Factors Affecting Coastal Environments 4 Geology 3 How does rock composition affect the coastline? | Coastal processes that operate on coasts consisting of different types of rock result in coasts with different coastlines. A coastline is the outline or contour of a coast. It is usually seen at the mean sea level, which is the average between high tide and low tide levels. |
| Factors Affecting Coastal Environments 5 Types of Ecosystems What is an ecosystem? How do they affect coastal environments? | In a ecosystem, communities of plants and animals interact with each other as well as the environment. Examples of ecosystems in coastal environments include mangroves and coral reefs. They affect the rate of change of coastal environments by reducing the impacts of waves on coasts. |
| Factors Affecting Coastal Environments 5 Types of Ecosystems 2 What are coral reefs? How do they do what they do? | Coral reefs are structures comprising colonies of billions of tiny polyps. They develop on the sea bed slightly below sea level. Coral reefs provide natural barriers that help slow down the speed and impacts of waves on the coastline. |
| Factors Affecting Coastal Environments 5 Types of Ecosystems 3 What can mangroves do? | Mangroves, with their special aerial roots, help trap sediments and reduce coastal erosion. Over time, the trapped sediments can form small islands and extend the coastline further seawards. |
| Factors Affecting Coastal Environments 6 Human Activities How do they affect the coasts? | People change coastal environment by living, trading, fishing and engaging in recreational activities in these environments. For example, people alter coastlines when they build marinas and port facilities. People can also cause pollution in these environments by dumping waste. |
| Generating Waves How do they develop? | Waves develop when the energy from the wind blowing acrooss seas and oceans is transferred to the water surface. The movement of waves is affected by wind direction. Onshore winds push waves towards the coast, resulting in waves crashing onto the shore. |
| Generating Waves 2 Wave Terminology | (Refer to page 9 of textbook) |
| Generating Waves 3 Factors Affecting Wave Energy Wind Speed | The faster the wind blows, the greater the wave energy is |
| Generating Waves 3 Factors Affecting Wave Energy 2 Duration of Wind | The longer the wind blows, the larger the waves are. |
| Generating Waves 3 Factors Affecting Wave Energy 3 Duration of Wind | The greater the fetch the more theenergy the waves have. Fetch is the distance the wind has travelled over the seas and oceans to form waves. |
| Generating Waves 3 Factors Affecting Wave Energy 4\ How to tell a large wave? | The amount of energy in waves can be seen from the wave steepness and wave period. Wave steepness is the ratio of wave height to wave length. The higher the wave energy is, the steeper the wave and the shorter the wave period becomes |
| Generating Waves 4 Waves in the Open Ocean What are its characteristics? | Waves in the open ocean have a long wave length and a low wave height |
| Generating Waves 4 Waves in the Open Ocean 2 How do water particles move? | Water particles in the open ocean move in an orbit, a motion that rapidly decreases with depth. In theory, water particles move through the surface of the water in a full orbit. The time it takes the water to complete this orbit is the time 2 successive crests or troughs take to move through a point. In reality, however, water particles do not make full orbits. This causes any objects to move slightly forward in the ocean |
| Generating Waves 5 Waves Close to the Coastline Stage 1 | Near the coastline, the water is shallow and the waves interact with the sea bed. The waves start to change their shape at a depth that is equivalent to about half of their wave height |
| Generating Waves 5 Waves Close to the Coastline Stage 2 | Nearer the coastline, as the waves continue to move in the shallow water, the base of the wave starts to slow down due to friction. This causes the wave height to increase and the wave length to decrease. |
| Generating Waves 5 Waves Close to the Coastline Stage 3 | Nearest the coastline, the base of the wave stops but the wave crest becomes steeper and topples over. This causes the wave to break onto the coast, releasing the energy of the wave. (Surfers ride on these breaking waves) |
| Generating Waves 5 Waves Close to the Coastline Stage 4 | When energy within a wave is released on the coast, it breaks down rocks along the coastline into smaller particles. These particles are then moved away to other parts of the coast. Waves are key forces of change, creating coastal environments which vary from place to place. |
| Waves Affecting Coastal Areas Waves on the Beach Swash and Backwash | When waves break, water rushes up a beach. This is swash. As swash moves up the beach, it carries sediments with it. Swash loses energy due to gravity and friction with the land, and returns to the sea as backwash. The backwash carries sediments from the shore into the sea. |
| Waves Affecting Coastal Areas 2 Types of Waves Constructive Waves | Constuctive Waves break far from the shore and with little energy. They occur in calm weather on gently sloping coasts. Consturcitve waves have a strong swash but a weak backwash. |
| Waves Affecting Coastal Areas 2 Types of Waves Constructive Waves 2 | Landforms such as beaches are 'constructed' by strong swash accompanied by weak backwash. The strong swash deposits sediments on the coasts while the weak backwash removes only little materials. Over time, the coasts are built up by the deposited sediments, forming sandy beaches. |
| Waves Affecting Coastal Areas 2 Types of Waves 2 Destructive Waves | Destructive waves break violently on the shore with high energy. There is often a steep slope that causes the waves to break and plunge directly down the beach. Destructive waves produce a weak swash but a strong backwash. |
| Waves Affecting Coastal Areas 2 Types of Waves 2 Destructive Waves 2 | Instead of depositing sediments on coasts, destructive waves erode coasts and transport rocks and beach material away. |
| Waves Affecting Coastal Areas 3 Wave Refraction What is it? What is the result of it? | Wave refraction is the process by which waves change direction as they approach a coast. Waves tend to converge on headlands, giving rise to increased wave height and greater erosive energy. However, when waves approach bays, they diverge, resulting in decreased wave height and reduced erosive energy. |
| Waves Affecting Coastal Areas 3 Wave Refraction 2 What happens when waves approach a coast? What are the impacts of wave refraction? | When waves approach a relatively straight coast at an angle, they are refracted and break almost parallel to the coast. The impact of wave refraction on the shoreline is uneven. |
| Waves Affecting Coastal Areas 3 Wave Refraction 3 Diagram | (Refer to page 13 of textbook) |
| Coastal Processes Coastal Erosion Hydraulic Action | When waves strike against a rock surface, the waves trap air in the rock joints. The air is compressed by the oncoming waves, exerting pressure on the joints. As the air is repeatedly compressed, the joints weaken and the rocks shatter. |
| Coastal Processes Coastal Erosion 2 Abrasion/Corrasion | As waves break, sediments carried by the waves such as sand and rocks are hurled against the coast. The loosened sediments knock and scrape against the coastal cliffs. This weakens the surface and breaks down the coast. Over time, the impact from abrasion is powerful enough to undercut a cliff |
| Coastal Processes Coastal Erosion 3 Attrition | When rock particles carried by waves rub or hit against one another, they break down into smaller pieces and become smoother and more rounded over time. |
| Coastal Processes Coastal Erosion 4 Solution/Corrosion | Sea water reacts chemically with water-soluble minerals in coastal rocks and dissolves them. For example, limestone rocks are easily eroded by carbonic acid. When solution of minerals occurs, rocks are weakened and eventually disintegrate. |
| Coastal Processes Coastal Erosion 5 Diagram | (Refer to page 15 of textbook) |
| Coastal Processes 2 Sediment Transport What processes cause this? | Sediments are transported along coasts through 2 related processes: beach drift and longshore currents. These processes are the result of waves approaching the coast at an angle. |
| Coastal Processes 2 Sediment Transport 2 How does beach drift form? | As waves approaching the coast at an angle break on the beach, sediments move up the beach at an angle as swash and move perpendicularly down the beach as backwash. This resultant zigzag movement along the beach is known as beach drift. |
| Coastal Processes 2 Sediment Transport 3 How do longshore currents form? What is it? | When waves approach the coast at an angle, they generate longshore currents in the nearshore zone and move sediments along the shore. Longshore currents are ocean currents that flow parallel to a coast. |
| Coastal Processes 2 Sediment Transport 4 What is longshore drift? | The combined effect of sediment movement by longshore currents and beach drift is known as longshore drift. Longshore drift is the most rapid when waves approach at an angle of 40 to 50 degrees. |
| Coastal Processes 2 Sediment Transport 5 Diagram | (Refer to page 16 of textbook) |
| Coastal Processes 3 Sediment Deposition How does it happen? | Sediments eroded from the coast are transported away and deposited elsewhere. When wave energy decreases, the waves are unable to carry these sediments. Large sediments are deposited first, followed by smaller sediments. Deposited sediments vary in type and size, resulting in a variety of beaches. |
| Coastal Processes 3 Sediment Deposition 2 What factors affect the deposition of sediments? | The location of coasts influences the deposition of sediments. In areas where coasts are sheltered from strong winds, destructive waves are less common. Fine sediments are deposited along sheltered coasts with calm waters such as mangrove coasts. In large sheltered bays, sandy beaches are common. On the other hand, coarser sediments are likely to settle in small bays. |
| Cliffed Coasts Cliffs and Shore Platforms What is a cliff? How is it produced? | A cliff refers to a steep and near-vertical rock face found along coasts. It is produced by the action of waes undercutting a steep, rocky coast. |
| Cliffed Coasts Cliffs and Shore Platforms 2 Diagram | (Refer to page 20 of textbook) |
| Cliffed Coasts Cliffs and Shore Platforms 3 How does a notch form? How does a cave form? How does a cliff form? | Hydraulic action and abrasion may erode a crack or joint on the rock surface, gradually enlarging the crack or joint to form a notch. This notch may be further deepened to produce a bigger hollow space called a cave. Further erosion by the waves eventually causes the roof of the cave to collapse and form a steep cliff. |
| Cliffed Coasts Cliffs and Shore Platforms 4 How does a shore platform form? What is it? | As the process of erosion continues, an overhanging cliff is formed. Eventually, this overhanging cliff will collpase and the materials will be deposited at the foot of the cliff. Some of these materials may be carried by waves and thrown against the base of the cliff, thus causing further erosion. Over time, the cliff will retreat inland and a gently sloping platform appears at the base where the cliff used to be. This platform is called a shore platform, which is submerged during high tides. |
| Cliffed Coasts 2 Headlands and Bays Type of Coastlines How are bays formed? | Some coastlines have alternate bands of more resistant and less resistant rocks arranged at right angles to the coast. The less resistant rocks will be eroded faster than the more resistant rocks. When less resistant rocks are eroded away, bays are formed. |
| Cliffed Coasts 2 Headlands and Bays 2 What type of coast is formed? How are headlands formed? | These are indented coasts. The remaining more resistant rocks which extend into the sea are known as headlands. |
| Cliffed Coasts 2 Headlands and Bays 3 Diagram | (Refer to textbook page 20) |
| Cliffed Coasts 3 Caves, Arches and Stacks How does a cave form? | Within headlands, some rocks may be less resistant to erosion than other rocks. These parts of the headlands will be eroded more quickly, especially by hydraulic action and abrasion. Waves attack lines of weakness such as joints and faults at the base of the headland and undercut it. The continuous action of waves forms a cave at the area that is hollowed by wave action. |
| Cliffed Coasts 3 Caves, Arches and Stacks 2 How does an arch form? | Caves may develop on each side of the headland. Erosion may eventually join caves together, leaving a bridge of rock known as an arch above the opening |
| Cliffed Coasts 3 Caves, Arches and Stacks 3 How does a stack form? How does a stump form? | After a period of time, the roof of the arch may collapse to form a stack. A stack is a pillar of rock in the sea left behind after an arch collapses. The stack will be attacked at the base by wave action. This weakens the structure and it will eventually collapse to form a stump. |
| Depositional Coasts Beaches What is a beach? What is it made up of? | A beach is a zone of sediment deposition, usually formed from loose sand, gravel, pebbles, broken shells and corals, or a mixture of these materials. Beach materials may come from eroded cliffs, river deposits and sediments carried by waves. |
| Depositional Coasts Beaches 2 Composition and Size of Materials | The composition and size of the materials on the beach vary greatly. The composition of materials depends on the source of materials. The size of materials may decrease over time due to the changes in weather conditions, wind direction, wave energy and ocean currents. |
| Depositional Coasts Beaches 3 What determines the slope of the beach? | The slope of the beach is determined by grain size. Finer grain size tend to result in beaches with a gentle gradient. On the other hand, materials of coarser grains form beaches with a steeper gradient. |
| Depositional Coasts Beaches 4 What changes the beach? | Beaches are constantly changing as their shapes are affected daily by waves, tides and currents. For example, during calm weather, constructive waves can help deposit materials on the beach and build up further. On the other hand, during coastal storms, stong waves will erode and remove materials from the beach. |
| Depositional Coasts 2 Spits and Tombolos What is a spit? | A spit is a long narrow ridge of snad or pebbles with one end attached to the land. |
| Depositional Coasts 2 Spits and Tombolos 2 How is a spit formed? | A spit is formed by longshore drift. Along some coasts where the direction of the coastline changes abruptly, longshore drift continues to transport materials in the original direction for some distance. The materials are deposited in the sea where they accumulate over time. The accumulated materials will appear above the surface of the water, forming a spit. |
| Depositional Coasts 2 Spits and Tombolos 3 How does a hook or curve form? | A hook or a curve may develop at one end of the spit, most likely due to wave refraction concentrating at that point. |
| Depositional Coasts 2 Spits and Tombolos 4 How is a tombolo formed? | A spit has one end connected to a mainland and has another end projecting out into the sea. If an offshore island lies near the mainland where the spit is forming, the spit may continue to extend until it connects the offshore island to the mainland. This new landform is called a tombolo. A tombolo may also join 2 existing islands. |
| Depositional Coasts 2 Spits and Tombolos 4 Diagram of Spit Formation | (Refer to page 28 of textbook) |
| Depositional Coasts 2 Spits and Tombolos 5 Diagram of Tombolo Formation | (Refer to page 29 of textbook) |
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