By Andrew Burke, James Ferguson and Chris Silins

 Located on Dorset/Devon border on South coast  Lies on a sequence of rocks through geological time: Triassic, Jurassic and Cretaceous periods  Older rocks in the west, younger in the east

 Located on Dorset/Devon border on South coast  Lies on a sequence of rocks through geological time: Triassic, Jurassic and Cretaceous periods  Older rocks in the west, younger in the east

At Lyme Regis:  Triassic rock disappears below see level  Jurassic rocks form the cliffs (Blue Lias) – 200m years old Formation:  Deposits from deep tropical sea with marine life – fossils Due to weak properties of Lias Clay and coastal erosion, multiple landslides have occurred.

 Strong bedrock overlaid by unstable slippery clays  The angle of the layers - makes sliding easier  Sea erodes bottom of slide & undermines old defences  Beach eroded reducing protection  Buildings damaged  Landslides expand inland

 Predictions for the likelihood of ground movement in the East of the town over the next 20 years

 The area was split into five sections  Prioritised due to potential risks and cost

BEFOREAFTER Phase I: a new sea wall and a rock armour revetment

Four main parts: 1. Foreshore works – extra sand and shingle – Extending rock armour/renovating existing rockery 2. Land stabilisation – piling of soil – new drainage – slope re-grading and some buttress building 3. Road improvements 4. Landscaping

Problem: Monmouth Beach is changing shape such that the crest height is reducing in the west. Consequences: Property on the beach will become more vulnerable to flooding and erosion. Solution: Decided to leave and monitor Cost vs. risk

Problems  High probability there will be a major landslide within the next 1 to 5 years.  The sea wall is under threat from large-scale cliff failure.  The drainage system has defects and its outfall is under threat from continuing ground movements.  The sea wall is being outflanked at its eastern end.  The shore platform is deteriorating leaving little beach material to protect the sea wall

Problems  The lower parts of the High Wall are deteriorating and are difficult to maintain.  The Low Walkway is vulnerable to scouring by seawater and shingle overtopping the High Wall during storms.

 Large areas of Lyme Regis are at risk from coastal erosion and landsliding including:  Solution split into five stages.  The schemes are being implemented over a period of time  The total cost of implementing all the schemes is estimated to be £33M  There would also be considerable secondary benefits to the environment and society of implementing the schemes.