GEOGRAPHY COASTS REAL EQ 1

• A coast is a zone where the land meets and interacts with the sea.
• A coast is a result of interactions between the land, water, air and living things.
• The offshore is the part which is submerged before meeting the land.
• The foreshore is the part where the low tide shoreline meets the high tide shoreline.
• The backshore is the part where the high tideline meets the highest water line.
• A berm is an elevated bump of sand.
• The natural processes that occur in coasts are waves, tides and sea level changes, ocean currents, geology and the types of ecosystems.
• Waves are generated by wind blowing across sea or oceans. They shape the coastal areas when hitting the land.
• The highest part of the wave is known as the crest. The lowest part of the wave is known as the trough. The distance between the crest and trough is known as the wave height.
• The distance between two crests is known as the wavelength.
• Wave steepness is the ratio of the wave height to the wavelength.
• The number of wave crests that pass through a point per second is known as wave frequency.
• The time taken for wave to travel is known as wave period.
• A short wave period means there is a high wave frequency. A long wave period is has a shore wave frequency.
• When water molecules touch the seabed, friction is created and it cannot move as fast. The wavelength becomes shorter and the wave height increases, causing the top of the wave to bend into a plunging breaker.
• The water that flows up the shore is the swash. The water that flows down the shore is the backwash.
• When water is more shallow, the circular motion becomes more elliptical, causing the crest of the wave to rise up and topple onto the beach.
• The factors that affect wave energy is windspeed, length of fetch and wind duration.
• Fetch is the length of open water in which the wind can blow unobstructed.
• Destructive waves are big, strong waves when the wind is powerful and has been blowing for a long time. It could also be because the wave has travelled over a long fetch. Destructive waves erode coasts. They have a stronger backwash than swash. Thus, more sediments are carried away, leading to erosion.
• Destructive waves have a short wavelength, are high and steep and have plunging breakers. They hit steep coastlines.
• Constructive waves are gentler and have spilling breakers. They deposit materials on shores. They have a long wavelength, have a stronger swash than backwash, are low in height. It is of a low wave frequency. They hit gentler coastlines.
• Tides and sea level changes refer to the rise and fall in sea level, caused by the gravitational pull of the moon and earth.
• Ocean currents are large scale, continuous movement of water in sea and in oceans. They are made from the Coriolis effect (caused by the rotation of the earth, causing winds to be deflected.) They can be warm or cold and shape the mircoclimate (climate that affects a small area of coastal area.)
• Geology refers to the arrangement and composition of rock. Well joined rocks have more lines of weaknesses.
• The erosion processes are hydraulic action, abrasion, attrition and solution.
• Hydraulic action takes place when waves hit against lines of weaknesses in rocks. This causes the air between them to compress and causes pressure, which makes the rocks weaken and crack.
• Abrasion is when sediments carried by waves are hurled onto rock and weaken them.
• Attrition takes place when the sediments carried by waves knock and rub against each other, causing them to become smaller and erode.
• Corrosion is when seawater reacts chemically with soluble materials in rock, causing them to dissolve. This weakens rocks and they disintegrate, eroding.
• When sediments become too heavy, the currents drop the load at the coast. This is known as coastal deposition.
• This occurs when 1. Waves enter an area of shallow water. 2. Waves enter a sheltered area like coves. 3. Good supply of material.
• Materials from coastal areas are from erosion of cliffs, transported by longshore drift, and brought inland by constructive waves.
• Saltation is when the load is bounced along the sea bed as currents cannot keep up with the larger and heavier sediments.
• Traction is when pebbles and larger sediment are rolled along the seabed.
• When a notch is found in a cliff, the waves attack it and through hydraulic action, it widens and forms a cave. The overhang collapses due to a lack of support and the cliff retreats inland to form a new cliff. The original place of the cliff is known as the wave-cut platform.
• When sea attacks a coast with alternating bands of soft and hard rock, the soft rock erodes first, retreading inland. The space where it once was fills with water and is known as a bay. The wave energy is dispersed at the bay, resulting in constructive waves. The hard rock does not erode easily. This causes it to jut out and it is known as a headland. The coastline is thus irregular. The wave energy concentrates around the headland due to wave refraction, causing destructive waves. This can only take place in discordant coasts.
• When a notch is found in a cliff at the same place, at opposite sides, it erodes and widens due to wave energy. Eventually, a tunnel is formed. The wave continues to attack it and the tunnel widens. The arch above this is unable to continue supporting it and falls. Thus, a stack is formed. The stack is attached by waves and forms a stump, which can only be seen during low tide.
• Depositional landforms are beaches made of eroded material.
• The cross section of the beach is known as the beach profile.