Include relevant key terms. main land uses and the geology of the Purbeck coast and Isle of Purbeck (you will explain how the geology has influenced the development of these coastal features. Read through all the information cards, examine the geology, Ordnance Survey With reference to a variety of coastal features annotate your sketch map with detailed diagrams (use the satellite and information card photos) to show and 2. On A3 paper, draw and annotate sketch maps at different scales to show the AS Explain the relationship between geology and coastal form along one named Maps and satellite images. need to develop a key). stretch of coast (6 marks) Exam Practice: Task: Hint – Refer to specific named locations, geology rock types, explanations should include reference to the 5 factors that affect coastal morphology from lesson 2.i Include relevant key terms.

Sand and clay relatively unconsolidated Mainly limestone, strong and hard but with regular joints Mainly clay, relatively unconsolidated Sand and clay relatively unconsolidated Relatively unconsolidated Mechanically strong

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Discordant Coasts The geology of the cliff is a really important factor that influences the rates of erosion. The resistance of rock essentially determines differential rates of erosion. As we can see in Swanage, along the (very beautiful) Dorset coast. Two headlands, Ballard Point (chalk) and Durlston Head (limestone) of harder rock types are more resistant to erosion. As a result they jut out to sea, forming headlands. The softer clays of Swanage have eroded much faster to form the bay. Coastlines, where the geology alternates between strata (or bands) of hard rock and soft rock are called discordant coastlines. Concordant Coasts Dominated by limestone it has the same type of rock along its length. Concordant coastlines tend to have fewer bays and headlands. A close up of Lulworth Cove in the map below shows that bays and coves can form at concordant coasts, once gaps in the resistant rock becomes breached. In this case, the Portland limestone has been breached at several points. Once broken through, the clay can be easily eroded to form a cove. Dalmatian Coasts This is an example of a concordant coastline. They have formed as a result of a rise in sea level. Valleys and ridges run parallel to each other. When the valley flooded because of the rise in sea level, the tops of the ridges remained above the surface of the sea as a series of offshore islands that run parallel to the coast. The best example of a Dalmatian coastline is Croatia (there is also a good example on the Pacific coast in Southern Chile.

The cliffs at Kimmeridge Bay contain a very thick sequence of Kimmeridge Clay (exposed, at low tides) and layers of mudstones, thin shales and resistant yellow-brown dolomites, (the stone bands). Each rock layer provides a look back through geological time. Providing an excellent record of the Jurassic period. erosion of the less-resistant clays behind the limestone led to the formation of the cove or bay. Over time the sea gradually eroded the resistant Purbeck limestone at the entrance to Lulworth Cove. Then rapid which are relatively unconsolidated. Cliff recession takes place at a At Kimmeridge Bay, the cliffs consist of less resistant clays faster rate .

At Stair Hole, the sea has eroded through the limestone and clays to create a small cove. It shows the Lulworth Crumple, an excellent example of limestone folding. The limestone and shale strata were folded due to tectonic movements 30mn yrs ago when the African plate collided with the European Plate arch . Formed by the erosive power of Durdle Door is an impressive natural the sea on the vertical layers of different types of rock. At some point in the past the sea would have begun to breach the hard Portland Limestone. And then more easily erode the softer Wealden beds Behind it. Warbarrow Bay was formed in a similar way to Lulworth Cove. The less resistant wealden clay has been eroded by the sea to expose the layers of chalk behind,. This chalk now forms the cliffs of the bay.

Haff Coasts Theses coasts consist of concordant features – long spits of sand and lagoons – aligned parallel to the coast. They are named after lagoon, or Haffs, of the southern shore of the Baltic Sea, which are enclosed by sand spits or dunes. Swanage Bay consists mainly of unconsolidated Wealden clay which is less resistant to erosion. These soft cliffs are subject to weathering processes as well as marine erosion. Nearer to the town of Swanage groynes have been installed to slow the process of Long shore drift and build a beach. This is good for tourism as well as protecting the cliffs from erosion. The Foreland is a sedimentary chalk headland, South of Studland. Weathering and erosion of the headland over thousands of years has formed features such as Old Harry (Stack), Old Harry’s wife (stump) as well as cave and arch features.

Headlands and bays affect incoming waves in different ways: Headlands force the incoming waves to refract or bend, concentrating their energy at eh headland. This increases the waves’ erosive power, steepening the cliffs and forming caved and arches. Bays when waves enter a bay their energy is dissipated (spread out) and reduced. This leads to deposition of sediment and forms a sand or shingle beach. Durlston Head is a headland of Portland and Purbeck limestone. It has created steep cliffs at Durlston as well as at Peveril Point (seen in the distance on the photo). However, the limestone is jointed, which has created lines of weakness that can be more easily eroded in places by marine and aerial processes.