Method of Data Collection The Data Was Collected on March 30th 2011 at Robins Bay St. Mary. Tables, along with labeled diagrams, were used to present the data. 6 Presentation, Analysis and Discussion of Data Sea Well Landforms: y Cave y Notch y Headland Time(s) 60 60 60 Wave Data Table 1 Number of waves 15 16 14 Period(s) 2 1 1 Wave Frequency 15 12 13 Waves Table 2 Wave Height(ft. ) 1. 2 1. 8 2. 1 Wave Length(ft. ) 5. 2 5. 8 6. 7 7 Wave Action The power of waves is one of the most significant forces of coastal change. Waves are created by wind blowing over the surface of the sea.
As the wind blows over the sea, friction is created – producing a swell in the water. The energy of the wind causes water particles to rotate inside the swell and this moves the wave forward. The size and energy of a wave is influenced by: y y y how long the wind has been blowing the strength of the wind how far the wave has travelled (the fetch) Waves can be destructive or constructive.
When a wave breaks, water is washed up the beach – this is called the swash. Then the water runs back down the beach – this is called the backwash. With a constructive wave, the swash is stronger than the backwash.With a destructive wave, the backwash is stronger than the swash. Figure 1 showing Waves Action. 8 Destructive Waves Destructive Waves is a plunging wave, with a short wavelength, a high frequency (13- 15 per minute) a high crest. Backwash greatly exceeds swash. Destructive waves comb beach material seawards. Figure 2 showing Destructive waves.
This wave was present at all locations. Constructive Waves A low frequency (6-8 per minute) spilling wave, with a long wavelength and a low crest, running gently up the beach. Swash greatly exceeding the backwash (which is reduced by percolation), leading to deposition.Figure 3 showing Constructive waves. This wave was present at Don Christopher Cove and Peytons Cove. 9 Cave Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process. Cave Figure 4 showing Cave. This landform was present at Sea Well and Peytons Cove and Point. 10 Notch A V-shaped cut or hole in the bottom or edge of a surface, normally a cliff. This is formed after repeated beating of waves, destructive, on the side of a cliff. Notch Figure 5 showing a notch.This landform was present at Sea well only. 11 Headlands Headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock. The bands of soft rock, such as sand and clay, erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland. Headland Figure 6 showing Headland. This landform was present at Sea Well, Don Christopher Point and Blowing Point. 12 Robins Bay Landforms: y Stacks Time(s) 60 60 60 Wave Data Number of Waves 12 15 13 Period(s) 1 2 1 Wave Frequency 11 13 14 Waves Wave Height(ft. ) 1. 2 2. 1 1. 9Wave Length(ft. ) 10 9. 3 8 13 Stack A stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, isolated by erosion. Stacks are formed through processes of coastal geomorphology, which are entirely natural. Time, wind and water are the only factors involved in the formation of a stack.  They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island.Without the constant presence of water, stacks also form when a natural arch collapses under gravity, due to sub-aerial processes like wind erosion. Stacks Figure 7 showing Stacks. This landform was present at Robins Bay, Don Christopher Cove and Peytons Point. 14 Don Christopher Cove and Don Christopher Point Landforms: y Platform y Cliff y Cove y Beach y Inlet y Stack (Figure 6) y Headland (Figure 5) Comprised of Mainly: y Sand y Shingle The Cove was filled with deposit materials. Wave Data Table 1 Number of waves 21 25 20 Time(s) 60 60 60 Periods(s) 1. 5 2 1 S 1 2 3 4 5 6 7 8 9SH SA SA SA A SA A SA SA SA Sediment Characteristics Table 2 L. A S. A 11 5. 5 15. 5 11 10 5 14 9. 5 9 7 14 2. 5 7 3. 5 8. 5 6 13 7. 5 T SS SS SC SC SS I I SS SS Wave Frequency 13 12 13 13 Waves – Table 3 Wave Height(ft. ) 1. 2 1. 1 1. 6 1. 4 Wave Length(ft. ) 9. 8 10. 6 11. 3 12. 7 15 Cliff and Wave Cut-off Platform A cliff is a steep rock face usually facing the sea. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts and along rivers. Cliffs are usually formed by rock that is resistant to erosion and weathering.Sedimentary rocks are most likely to form sandstone, limestone, chalk, and dolomite. Igneous rocks, such as granite and basalt also often form cliffs. Wave-cut platform is the narrow flat area often found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was created by the action of waves. Wave-cut platforms are often most obvious at low tide when they become visible as huge areas of flat rock. Sometimes the landward side of the platform is covered by sand, forming the beach, and then the platform can only be identified at low tides or when storms move the sand.Figure 8 showing Cliff and Wave Cut Platform. This landform was present at Don Christopher Cove and Peytons Point. 16 Cove and Beach A cove is a small type of bay or coastal inlet. They usually have narrow, restricted entrances, are often circular or oval. Coves, like bays, are formed by differential erosion. Differential erosion is when softer rocks are worn away faster than the harder rocks surrounding them Beach an accumulation of sediment deposited by waves and long shore drift along the coast. The upper limit is roughly the limit of high tide; the lower, of low tide. Cove Figure 9 showing a Cove. BeachFigure 10 showing a Beach. These landforms were present at Don Christopher Cove and Peytons Cove. 17 Inlet An inlet is a narrow body of water between islands or leading inland from a larger body of water, often leading to an enclosed body of water, such as a sound, bay, lagoon or marsh. In sea coasts an inlet usually refers to the actual connection between a bay and the ocean and is often called an “entrance” or a recession in the shore of a sea, lake or river. A certain kind of inlet created by glaciations is a fjord, typically but not always in mountainous coastlines and also in montane lakes. Inlet Figure 11 showing an Inlet.This landform was present at Don Christopher Point 18 Peytons Cove and Peytons Cove Landforms: y Cove (Figure 8) y Beach (Figure 9) y Stacks(Figure 6) y Cliff (Figure 7) y Notch(Figure 4) y Arch y Stump Compose Mainly of: y Fine sand (Rounded) y Limestone y Pebble y Deposition Large Destructive Waves were seen but too dangerous to record any data. 19 Arch and Stump Arch, found mainly on a coast, is made when a cave on either side of a headland meet. Arches are temporary; roof falls cut off the seaward end of the arch, which is then left as a stack. A stump is low outcrop of rock formed by the erosion of a coastal stack.Unlike a stack, which is exposed at all times, a stump is exposed only at low tide. Eventually it is worn away completely. Figure 12 showing Arch and Stumps. Arch Stumps These landforms were present at Peytons Cove and Point. 20 Blowing Point Landforms: y Headland(Figure 5) y Blowhole Blowing point had large sharp rocks. Very large destructive waves were seen but too dangerous to record data. 21 Blowhole Blowholes are formed as sea caves grow landwards and upwards into vertical shafts and expose themselves towards the surface, which can result in blasts of water from the top of the blowhole.A blowhole is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to pressure differences between a closed underground cavern system and the surface. Blowhole Figure 13 showing Blowhole. This landform is at Blowing Point only. 22 Hydraulic action. Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion. Abrasion. Bits of rock and sand in waves grind down cliff surfaces like sandpaper. Attrition. Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.Solution is minerals that dissolved in sea water and carried in solution. The load is not visible. Load can come from cliffs made from chalk or limestone, and calcium carbonate is carried along in solution. Suspension is small particles that carried in water, silts and clays, which can make the water look cloudy. Currents pick up large amounts of sediment in suspension during a storm, when strong winds generate high energy wave. Saltation is when load is bounced along the sea bed, small pieces of shingle or large sand grains. Currents cannot keep the larger and heavier sediment afloat for long periods.Traction is when pebbles and larger sediment are rolled along the sea bed Deposition When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition. Deposition happens when the swash is stronger than the backwash and is associated with constructive waves. Deposition is likely to occur when: y y y y Waves enter an area of shallow water. Waves enter a sheltered area, eg a cove or bay. There is little wind. There is a good supply of material. 23 Observation of Findings Sea Well Destructive waves were seen at Sea Well.The landform present proves that destructive waves are at Sea Well because of the landform. The Landform, which is cave, notch, headland, proves that the constant beating of waves on the rock structure present cause them to disintegrate eventually forming those structure Robins Bay Destructive waves were seen at Robins Bay and were shown in the data collected. The landforms which were there, Stacks, prove that the waves are destructive. Why? Because stacks are created by destructive waves. Constructive waves could form stacks but it would take a very long time for it to break down a headland into a cave then an arch then into the stack.Don Christopher Cove and Point Destructive waves were seen. The landforms present were platform, cliff, cove, beach, inlet, stack, headlands. The destructive waves created the platform, cliff, cove, inlet and stacks. Constructive waves created the beach, but no constructive waves were seen and none was recorded. Deposit material was seen on the beach, which is normally carried in constructive waves. Rocks on the beach were analyzed and data was collected. There was a large number and sandstones, which is a weak stone. Peytons Cove and Point Destructive waves were seen at this location.The destructive waves were so strong that we could not record any data. The landforms that were present were cove, beach, stacks, cliff, notch, arch, stumps. With the large destructive waves the landforms, cove, stack, cliff, notch, arch and stump, very disintegrated. There were a large number of stumps, which shows that a lot of headlands were broken down into caves then the caves were broken down in to arches then into stacks the stumps. A beach was also there which indicates that constructive waves are also present Blowing Point Very large destructive waves were seen.The rock structure was so disintegrated that a blowhole was at this location. 24 Conclusion A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term “coastal zone” can be used instead, which is a spatial zone where interaction of the sea and land processes occurs. The coast and its adjacent areas on and off shore is an important part of a local ecosystem as the mixture of fresh water and salt water in estuaries provides many nutrients for marine life.Salt marshes and beaches also support a diversity of plants, animals, and insects crucial to the food chain. The high level of biodiversity creates a high level of biological activity, which has attracted human activity for thousands of years. Waves often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges have fewer deposits. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal can erode as the waves surge up river estuaries from the ocean.Waves erode coastline as they break on shore releasing their energy; the larger the wave the more energy it releases and the more sediment it moves. Coastlines with longer shores have more room for the waves to disperse their energy, while coasts with cliffs and short shore faces give little room for the wave energy to be dispersed. In these areas the wave energy breaking against the cliffs is higher, and air and water are compressed into cracks in the rock, forcing the rock apart, breaking it down. Sediment deposited by waves comes from eroded cliff faces and is moved along the coastline by the waves.During this field trip a numerous different coastal landforms were seen. These landforms are wave cut-off platforms, beaches, coves, stacks, stumps, arches, caves, notch, cliffs, headlands, inlet and blowhole. Most of these landforms are erosional landforms which were created by destructive waves. The other is depositional landforms which are created by constructive waves. Coastal Processes such as hydraulic action, abrasion, attrition, solution, suspension, saltation and traction all contribute to the erosion and deposition of the coast. 25 Bibliography 26