WEBVTT 00:00:00.500 --> 00:00:03.975 Welcome to GCSE A Q A Geography revision. 00:00:04.125 --> 00:00:07.415 Topic G 10: Coastal landscapes in the UK. 00:00:07.565 --> 00:00:09.549 This is an optional topic. 00:00:09.699 --> 00:00:12.950 Study it if it is one of the options taught by your school. 00:00:13.100 --> 00:00:17.953 Use your school’s selected case studies if they differ from these revision examples. 00:00:20.633 --> 00:00:24.236 Waves form when wind transfers energy to the sea surface. 00:00:24.386 --> 00:00:30.763 Stronger winds, longer wind duration and a longer fetch (distance over water) can produce larger waves. 00:00:33.433 --> 00:00:38.755 Swash is water moving up a beach after a wave breaks; backwash is water returning down it. 00:00:38.905 --> 00:00:43.379 Constructive waves usually have stronger swash than backwash and build up beaches. 00:00:46.033 --> 00:00:51.931 Destructive waves usually have stronger backwash relative to swash and tend to remove beach material. 00:00:52.081 --> 00:00:58.437 They are commonly steeper and more frequent; actual beach change also depends on sediment supply and tides. 00:01:01.100 --> 00:01:03.404 Weathering breaks down rock in place. 00:01:03.554 --> 00:01:12.523 Mechanical weathering includes freeze to thaw where water freezes and expands in cracks; chemical weathering includes weak acids reacting with limestone. 00:01:15.200 --> 00:01:18.921 Mass movement is rock or soil moving downhill under gravity. 00:01:19.071 --> 00:01:27.134 Rockfalls involve blocks dropping from cliffs; slides move along a relatively straight surface; slumps rotate along a curved surface. 00:01:29.800 --> 00:01:34.059 Rain can saturate cliff material, adding weight and reducing friction. 00:01:34.209 --> 00:01:39.191 Wave erosion at the cliff foot can remove support, making slope failure more likely. 00:01:41.867 --> 00:01:46.473 Hydraulic power is erosion by wave force and compressed air in cracks. 00:01:46.623 --> 00:01:50.615 Abrasion is rock fragments hurled against a cliff, wearing it away. 00:01:50.765 --> 00:01:54.560 Attrition is fragments colliding and becoming smaller and rounder. 00:01:57.233 --> 00:02:00.057 Longshore drift moves sediment along the coast. 00:02:00.207 --> 00:02:08.088 Waves arriving at an angle move material diagonally up the beach in swash; backwash returns it down the slope, giving a zigzag path. 00:02:08.238 --> 00:02:10.307 Sediment moves along the beach. 00:02:10.457 --> 00:02:13.091 Swash follows waves approaching at an angle. 00:02:13.241 --> 00:02:17.968 Backwash runs down the beach slope; net movement is to the right in this example. 00:02:22.633 --> 00:02:27.418 Deposition happens where waves or currents have too little energy to carry sediment. 00:02:27.568 --> 00:02:33.743 Sheltered bays and shallow water can encourage accumulation; sediment size and supply also matter. 00:02:36.400 --> 00:02:41.562 On a discordant coast, alternating resistant and less resistant rocks meet the sea. 00:02:41.712 --> 00:02:47.140 Less resistant rock erodes faster into bays; more resistant rock remains as headlands. 00:02:49.800 --> 00:02:57.693 Geological structure affects erosion: joints and faults are lines of weakness, while the direction of bedding can affect cliff stability. 00:02:57.843 --> 00:03:02.077 On a concordant coast, rock bands run roughly parallel to the coast. 00:03:04.733 --> 00:03:07.187 Waves erode a notch near the cliff foot. 00:03:07.337 --> 00:03:14.962 Undercutting makes the rock above unstable, so it collapses and the cliff retreats, leaving a gently sloping wave-cut platform. 00:03:17.633 --> 00:03:20.841 Erosion enlarges cracks in a headland into caves. 00:03:20.991 --> 00:03:26.877 A cave may cut through to form an arch; collapse of the roof leaves a stack, which can erode into a stump. 00:03:27.027 --> 00:03:28.797 Erosion of a headland. 00:03:28.947 --> 00:03:31.379 Waves exploit weaknesses in the rock. 00:03:31.529 --> 00:03:35.605 This sequence develops over time, not during every single storm. 00:03:40.267 --> 00:03:43.199 Beaches are accumulations of sand or shingle. 00:03:43.349 --> 00:03:50.697 Their shape changes as waves deposit and remove material, and finer sediment usually forms gentler slopes than coarse shingle. 00:03:53.367 --> 00:03:59.126 Sand dunes form where dry beach sand is blown inland and trapped by obstacles or vegetation. 00:03:59.276 --> 00:04:03.384 Plants such as marram grass stabilise sand, helping dunes grow. 00:04:06.067 --> 00:04:12.551 A spit grows when longshore drift deposits sediment beyond a bend in the coastline or across part of an estuary. 00:04:12.701 --> 00:04:18.907 Changing wind or wave directions can curve the tip; sheltered water behind may support salt marsh. 00:04:21.567 --> 00:04:27.177 A bar can form when a spit extends across a bay and joins two headlands, enclosing a lagoon. 00:04:27.327 --> 00:04:32.841 A spit across a river mouth may remain incomplete because flowing water keeps a channel open. 00:04:35.500 --> 00:04:39.827 Hard engineering uses built structures to control coastal processes. 00:04:39.977 --> 00:04:47.187 Sea walls protect land behind them, but are expensive and can reflect wave energy, encouraging scour near their base. 00:04:49.867 --> 00:04:53.949 Rock armour absorbs wave energy through gaps between large boulders. 00:04:54.099 --> 00:04:59.515 It needs transport and maintenance and can restrict access or change the appearance of a beach. 00:05:02.167 --> 00:05:04.919 Gabions are wire cages filled with stones. 00:05:05.069 --> 00:05:11.061 They can be cheaper and absorb energy, but wire corrodes or breaks and damaged cages need maintenance. 00:05:13.733 --> 00:05:19.663 Groynes trap sediment moved by longshore drift, creating a wider beach that absorbs wave energy. 00:05:19.813 --> 00:05:25.017 They can reduce sediment reaching beaches farther along the coast, increasing erosion there. 00:05:27.667 --> 00:05:33.042 Beach nourishment adds sediment, while reprofiling reshapes the beach to absorb wave energy. 00:05:33.192 --> 00:05:37.909 These preserve a more natural appearance but may require repeated work after storms. 00:05:40.567 --> 00:05:45.919 Dune regeneration uses fencing, planting and controlled access to stabilise dunes. 00:05:46.069 --> 00:05:50.985 It can provide habitat and protection, but needs space and may limit recreation. 00:05:53.667 --> 00:06:00.737 Managed realignment allows the shoreline to move inland in a planned area, sometimes by breaching old defences. 00:06:00.887 --> 00:06:06.177 New salt marsh can absorb energy, but landowners may lose land and need compensation. 00:06:08.833 --> 00:06:15.627 Management decisions consider the value of assets, costs over time, habitats, sediment movement and climate change. 00:06:15.777 --> 00:06:21.227 Protecting one place can transfer problems elsewhere, so schemes need a wider coastal view. 00:06:23.900 --> 00:06:28.284 Dorset's coast includes resistant headlands and less resistant bays. 00:06:28.434 --> 00:06:37.799 Around Swanage, resistant chalk at Ballard Point and limestone at Durlston Head contrast with less resistant rocks in the bay, helping explain its shape. 00:06:40.467 --> 00:06:45.896 Old Harry Rocks near Handfast Point are chalk stacks and associated erosional features. 00:06:46.046 --> 00:06:52.979 Wave erosion along weaknesses separates parts of a headland, illustrating the cave to arch to stack sequence. 00:06:55.633 --> 00:06:58.701 Swanage and Studland have depositional beaches. 00:06:58.851 --> 00:07:06.829 At Studland, wind-blown sand has formed dunes behind the beach, linking wave deposition, wind transport and vegetation growth. 00:07:09.500 --> 00:07:16.411 The wider Dorset coast includes Chesil Beach, a long shingle barrier enclosing the Fleet lagoon along part of its length. 00:07:16.561 --> 00:07:21.392 Do not describe every Dorset beach as sand or every barrier as a simple spit. 00:07:24.067 --> 00:07:30.914 Swanage needs management to reduce wave damage and erosion affecting the town, seafront and visitor economy. 00:07:31.064 --> 00:07:37.121 Its developed frontage is defended, while approaches vary along less developed parts of the wider coast. 00:07:39.800 --> 00:07:45.292 The 2005 to 06 scheme combined timber groynes with beach replenishment. 00:07:45.442 --> 00:07:53.729 Groynes retain drifting sediment and the wider beach helps absorb wave energy; the scheme complements existing seawalls and needs maintenance. 00:07:56.400 --> 00:08:01.713 Residents and businesses benefit from protection, and a maintained beach supports tourism. 00:08:01.863 --> 00:08:09.209 Continuing inspections, groyne repairs and replenishment cost money, and works can temporarily affect access or beach use. 00:08:11.867 --> 00:08:17.774 Management has to consider sediment movement and environmental effects beyond the defended frontage. 00:08:17.924 --> 00:08:25.891 Defending developed areas while other cliffs retreat can create disagreement over fairness, future costs and which assets to protect. 00:08:28.567 --> 00:08:31.795 Treat new proposals separately from completed works. 00:08:31.945 --> 00:08:39.283 Shoreline change and rising sea level mean an existing scheme needs review rather than guaranteeing permanent protection. 00:08:41.933 --> 00:08:44.728 That completes Coastal landscapes in the UK. 00:08:44.878 --> 00:08:48.223 Revisit the notes and test yourself on the revision website.