The Afon Ogwen is a 20km long river flowing through the Ogwen valley in North Wales. The river’s source is in the Snowdonia National Park and its flows north to its mouth in the Bangor flats.
2. Explain how the human management of the Afon Ogwen river basin has helped shape its current appearance. (6)
The main land use in the Ogwen valley has traditional been pastoral farming. For the last two centuries sheep have been the dominant farm animal raised. As sheep like to each tree saplings, they have resulted in a landscape relatively free of trees, except in areas which are too steep for the sheep to access. The loss of shepherds, killed during the first world war, allowed Scots Pine trees to germinate and grow. Over 100 years later these trees can now be seen at the northern end of the Nant Ffrancon valley, south of Bethesda. The Ogwen valley landscape is divided into fields by dry-stone walls made up of local stone.
Rising above Bethesda, on the west bank of the Afon Ogwen, are the huge piles of slate waste from the Penrhyn slate mine. Dominating the landscape, the piles of grey broken slate give this section of the valley an industrial appearance. The colour of the waste is mirrored across the river by the walls and rooves of Bethesda, whose houses are also constructed from the same slate.
3. Describe some of the land uses which take place in a river valley drainage basin you have studied. (4)
The Ogwen Valley in North Wales is dominated by pastoral farming where sheep are raised for meat and wool. Approximately halfway between source and mouth is the Penrhyn Quarry. This slate mine is dominated by a huge hole in the ground with slate wastes piled high on the western bank of the Afon Ogwen. Across from the quarry is the village of Bethesda, a residential zone. In 2017 a small-scale hydro-electric generating station was opened just south of Bethesda, adding generation to the list of land uses in the valley.
4. Assess the relative importance of erosion and deposition in creating the different features of the Afon Ogwen valley. (8)
The upper and middle courses of the Ogwen valley are dominated by the features created by glacial erosion. The Afon Ogwen is a misfit stream, which means it valley was mostly eroded by a glacier, creating a steep-sided U-shaped glacial trough. Since the end of the last glaciation, the Afon Ogwen has begun to create a small V-shaped valley on the side of the main Ogwen valley, but the resistance of the rocks has limited the impact of this erosion.
As the river flows into the ribbon Lake of Llyn Ogwen, deposition of transported sediment has begun to create a flat delta at the western end of the lake. This process has been fully completed downstream of the Ogwen falls where deposition since the last glaciation has infilled a ribbon lake to form the floor of the Nant Ffrancon valley – a valley that falls by just 20 metres in height over five kilometres. Both Llyn Ogwen and the former lake in the Nant Ffrancon were formed by ridges of resistant rock which resisted glacial erosion and so resulted in a ridge of higher ground behind which the lakes formed.
5. Describe the main geomorphic processes operating in the upper course of the Afon Ogwen. (4)
In the upper course of the Afon Ogwen, both erosion and deposition are taking place. Large bed load, transported by traction along the channel bed, is eroding vertically by abrasion and hydraulic action, to create a small V-shaped valley, within the overall glacial trough. Deposition is occurring as the river flows in both the corrie tarn called Ffynon Loer (600m above sea level) and then again as the river flows into the ribbon lake called Llyn Ogwen (300m). Both these areas f deposition are creating river deltas of low plat lands building out into the lake.
6. Describe the orientation of a coastline you have studied. (2)
The North Wales coastline with the Irish Sea runs roughly west to east for approximately 40km from the Great Orme’s Head and the Conwy River mouth in the west to Talacre and the Dee estuary in the east.
7. Describe the cause and effect of longshore drift along a coastline you have studied. (6)
The North Wales coastline with the Irish Sea runs roughly west to east for approximately 40km from the Great Orme’s Head and the Conwy River mouth in the west to Talacre and the Dee estuary in the east. Since the coastline is protected from south-westerly winds and easterly winds have little time to develop waves along the coast, the most significant winds are those from the west and north-west. Longshore Drift acts to move sediment, in a zig-zag motion, along the coastline from the two headlands of the Great and Little Orme towards the east where sediment is deposited to form beaches. At the Point of Ayr at Talacre the beach as built out into the Dee estuary to form a spit.
8. Describe, and give evidence for, two geomorphic processes operating along a coastline you have studied. (6)
Erosion via abrasion (rocks rubbing against other rocks) and wave pounding (the sheer force of the water as waves break onto the coast or waves compressing air into cracks) can wear away coastal rocks to form cliffs with a wave-cut platform at their base. These features can be seen around the Great Orme’s Head on the North Wales coast at the mouth of the River Conwy. Longshore drift, the movement of sediment in a zig-zag motion along a coastline transports sediment along the coastline until it is deposited at a change in the coastlines direction. This process has helped from a spit at the eastern end of the North Wales coast at Talacre where a sand spit extends eastwards out into the estuary of the River Dee.
9. With reference to a coastline you have studied, describe how and why the coast is managed at different places. (6)
The eastern stretch of the North Wales coast runs from the Great Orme’s Head at the mouth of the River Conwy to Talacre on the River Dee. Erosion and longshore drift are active processes along the coast. In Llandudno Bay, the beach is backed by a promenade which prevents erosion. Recently sediment from the West Beach was collected and dumped on the North Shore to help create a wider beach. However, many locals complained of the unsightly rocks that were dumped along with the sand.
Further east near Raynes Quarry the coastline is protected by tetrapods, concrete interlocking structures which prevent erosion by dissipating wave energy. These tetrapods are needed to protect the coastline from erosion at this location as the railway line and North Wales Expressway run close to the sea. Further to the east from Rhyl through to Prestatyn the coast is managed by a combination of concrete resentments to prevent flooding, as well as rip-rap (stone) and wooden groynes to prevent eastwards longshore drift, creating wider beaches.
10. With reference to a coast you have studied assess the relative importance of both erosion and deposition in creating and shaping the features of that coastline. (8)
The eastern stretch of the North Wales coast runs from the Great Orme’s Head at the mouth of the River Conwy to Talacre on the River Dee. Both erosion and deposition occur along this coastline, as wells as transportation – the process of longshore drift. The most obvious features along the coast differ depending on which process is dominant. Around the Great Orme, in the west, erosion via wave-pounding and abrasion has created steep cliffs. Over time, sediment from the Orme and from the River Conwy has combined to create a tombolo (a spit connecting an island to the mainland) on which Llandudno is now built. The North beach in Llandudno shows evidence of longshore drift with material moved from the west to east along the shore.
East of the Little Orme, at Penrhyn Bay, a steep shingle beach of limestone fragments has been deposited from the material eroded from the limestone headland
At the far eastern end of the coastline, close to the River Dee, the shore displays evidence of deposition. Wide sandy beaches are found at Rhyl and Prestatyn. There are also depositional spits are the river mouths at Rhyl and Talacre. The different features demonstrate a complex relationship between the three interlinked processes of erosion, transportation and deposition, all of which are equally important in creating the varied features of this coastline.
11. Describe one method of coastal defence that is used on a stretch of coastline you have studied. (3)
East of Colwyn Bay on the North Wales coast, the coastline is defended from erosion by tetrapods. These are large concrete structures with four ‘legs’ which when placed along the coast interlock to create a complex sea wall. The gaps between the tetrapods act to dissipate and deflect wave energy breaking on the coast, so reducing erosion to a minimum. Each tetrapod is numbered and regular photographs are taken of the defences to check if any tetrapods have moved during storms.
10. With reference to a coast you have studied assess the relative importance of both erosion and deposition in creating and shaping the features of that coastline. (8)
The eastern stretch of the North Wales coast runs from the Great Orme’s Head at the mouth of the River Conwy to Talacre on the River Dee. Both erosion and deposition occur along this coastline, as wells as transportation – the process of longshore drift. The most obvious features along the coast differ depending on which process is dominant. Around the Great Orme, in the west, erosion via wave-pounding and abrasion has created steep cliffs. Over time, sediment from the Orme and from the River Conwy has combined to create a tombolo (a spit connecting an island to the mainland) on which Llandudno is now built. The North beach in Llandudno shows evidence of longshore drift with material moved from the west to east along the shore.
East of the Little Orme, at Penrhyn Bay, a steep shingle beach of limestone fragments has been deposited from the material eroded from the limestone headland
At the far eastern end of the coastline, close to the River Dee, the shore displays evidence of deposition. Wide sandy beaches are found at Rhyl and Prestatyn. There are also depositional spits are the river mouths at Rhyl and Talacre. The different features demonstrate a complex relationship between the three interlinked processes of erosion, transportation and deposition, all of which are equally important in creating the varied features of this coastline.
11. Describe one method of coastal defence that is used on a stretch of coastline you have studied. (3)
East of Colwyn Bay on the North Wales coast, the coastline is defended from erosion by tetrapods. These are large concrete structures with four ‘legs’ which when placed along the coast interlock to create a complex sea wall. The gaps between the tetrapods act to dissipate and deflect wave energy breaking on the coast, so reducing erosion to a minimum. Each tetrapod is numbered and regular photographs are taken of the defences to check if any tetrapods have moved during storms.
