Red Rock

Dawlish Warren is a renowned traditional holiday resort in South Devon, with its one and half mile long sandy beach, sheltered sand dunes and family amusements. But the geographical traits of the area, make the site unique. The Warren is being eroded at an increasing rate, raising concerns for the beach, the national nature reserve, main line railway, and people’s homes. The loss of sand on the beach, caused by longshore drift, affects not only the landscape, but the tourism industry, local economy and migrating species. The Environment Agency deals with the threat of flooding, while Natural England is responsible for managing the nature reserve.

The groynes at Dawlish Warren, are hydraulic structures partially submerged into the ocean, built to disrupt the natural flow of the water. Here they prevent the sand from being washed away by longshore drift. Long-shore drift, transports sediment along the coast, in the direction of the wave movement. At Dawlish Warren, the sediment is being pushed towards Exmouth, by the prevailing south and south-westerly winds, in a north easterly direction. In the early 1970s, 17 groynes were placed every 100meters along the beach to impede long-shore drift. In 2017, several existing groynes were demolished to prevent the structures forming dangerous points submerged under the sand. As part of the Dawlish Warren Beach Management Scheme, 4 new timber groynes were constructed, whilst three groynes were extended to increase their effectiveness. The new groynes, aimed to protect the 250,000 cubic metres of sand which was pumped on to the beach in July 2017.

Groynes provide habitat for aquaculture, such as mussels. Standing within the intertidal zone, where the land meets the sea, they are covered and uncovered daily by the ocean, forming unique and diverse living conditions for marine life. The lowest levels of the intertidal zone are the most crowded with life, and the higher, dryer levels are less populated. Along Dawlish Warren, the groynes on the South of Langstone Rock, radiate the blue tones of mussel shells. The tide on the south, comes higher than that of the north, completely submerging the remainder of the groynes on a daily basis. This has caused the area to be a thriving habitat. Wheres the newer groynes on Dawlish Beach, stretch further on to dry land, making them less attractive to marine life. It is suggested that the bottom of these groynes have not been used as a habitat, as they were submerged under the sand. With the long-shore drift, lower areas of the groyne have been exposed, but the ever changing environment is not sustainable to create a habitat.

A breakwater of granite blocks is attached to the east-most point of Langstone Rock. The stone groyne, attempts to hold back some of the sand and shingle from the South-west, that gets pulled towards the North-east with long-shore drift. But the shingle building up on the south of the groyne, has an abrasive action towards the red rock, fastening the process of erosion, adding to the formation of caves and the natural arch.

Devon’s ‘red county’ description is attributed to the red soils that are prominent in this region of the country. Langstone rock is a distinctive local geographic landmark, in the southwestern corner of Dawlish. The 15metres high Red Sandstone rock, holds features such as an arch, a blow hold and colourful vegetation. The red rock, is formed of breccia, a type of sedimentary rock that consists of angular fragments of stones, cemented together by fine-grained material. The rock battles against the sea, weathering and the vegetation that resides over its higher ground.

Hydraulic action causes air to be trapped in joints and cracks on a cliff face. When a wave breaks, the air is compressed which weakens the cliff. The soft sedimentary rock, is easily abraded by bits of rock and sand flung towards the surface by waves, creating an unsteady surface to the cliff, with a steep gradient.

In addition, under the sea, waves are smashing rocks and pebbles together causing them to break and become smoother, flattening the sea bed. The high tide, causes waves to reach Langstone rock, quickly eroding the lower levels, forming multiple caves that are constantly being attacked by erosion. The iconic arch that has formed, also gets targeted by weathering, as it stands nearly as tall as the cliff itself, the roof of the arch will eventually collapse, forming a stump in the sea.

In 1844, Brunel was appointed as chief engineer, to construct a new railway under the granting of the South Devon Railway Act. The railway was a continuation of the Bristol and Exeter Railway, west from Exeter to Plymouth. The railway was to be constructed over the hilly and curvy Devon terrain, creating a scenic route throughout Devon. Brunel, decided that the train line would run through Langstone Rock. The railway between Teignmouth and Dawlish travels along the sea wall, through dramatic coastal tunnels. The line is expensive to maintain but kept open because it is a vital communication link for the people and economy of the South-West.Â

how the train line was ruined

The Red Sandstone at Dawlish, is covered in vibrant green vegetation. Plants can grow in sedimentary rock, due to the process of weathering breaking down the breccia in to smaller pieces by water, wind and ice. Weathering causes the rock to slowly release minerals, and the nutrients that were trapped in the rock become available to plants growing on the surface. Organic sediment such as plant debris, animal sediment and micronutrients can all be captured by the rock, providing a varied source of nutrients for the plants.

Houses in Dawlish are sat on an inclining threat form erosion, and storms. The speeding erosion of the cliff edge, puts houses that are on the face of the cliff, at risk of eventually falling of the edge, which significantly reduces the value, and safety of their homes. In 2014, thousands of houses along this coastline were evacuated due to heavy flooding within villages. Waves smashed a 100ft section of the Sea Wall in Dawlish, caused by high winds whipping the waves high in to the air. Dawlish Warren village is currently at a 4% annual chance of tidal flooding.

The Sea Wall that follows the South Devon Railway line from Langstone Rock to Dawlish town, was constructed in 1992 to protect the railway line. It works in conjunction with the flood wall previously installed across the Warren to prevent flooding in Dawlish. The Sea Wall path can be used by pedestrians, but at high tide, the risk of being exposed to the high waves can be dangerous when walking along the wall. The walk takes you along the beach, accompanied by constant local, and cross-country trains travelling past, making it a scenic walk at low tide.

The Sea Wall protecting the south of Dawlish Beach, is formed of large granite boulders from Dartmoor National Park. The boulders provide extra protection for the sea wall along this area of Dawlish, sheltering the area which holds the amusement park, restaurants and RNLI life guard hut. The RNLI hut is manned daily in July and August, as Dawlish becomes a popular tourist destination due to the long, sandy beach. Due to the groynes in the water, people are advised to stay between the red and yellow flags, which are patrolled by lifeguards.

The Dawlish Warren Nature Reserve runs for 1 and a half miles along Dawlish Beach. Across the years, more and more areas of the dunes have been fenced to protect from continuing erosion. These areas are then planted with Marram Grass, which withstand the salt and sea salt, whilst trapping the blown sand. The Nature Reserve supports over 2000 species, 620 types of plant and 250 fungi, making it a site of regional significance for wildlife.

The combination of the Nature Reserve, resting on the sea front, creates a diverse landscape that has to be carefully controlled. Costal sea defences, such as groynes, and the sea wall, are key elements of preserving the landscape, to keep both the environment, and the residential areas safe from the elements.