Chalk coast dynamics: Implications for understanding rock coast evolution

Rock cliffs and shore platforms are linked components of the world's coastal zone. Understanding of the dynamics of their relationships has been hindered by the often imperceptible changes that occur within human time scales. The Cretaceous Chalk coasts of northwest Europe, and particularly those of southeast England, are among the most dynamic, and most intensively studied, cliffed rock coasts in the world. Perceptible changes to both cliffs and platforms have been measured on monthly, seasonal, annual and decadal time scales. Through a review of previously published data and the addition of data not previously published, average cliff retreat rates are calculated as 0.49 0.38 m y-1 and platform erosion rates 3.999 3.208 mm y-1. This paper highlights some of the interactions over time and space between process and measurement that continue to limit our understanding of the dynamics of rock coasts; in particular the link between rates of cliff retreat and platform erosion. It concludes by identifying fruitful areas for future research. Keywords: Rock coast, cliff, shore platform, Chalk, coastal erosion, weathering

[1]  J. Hall,et al.  A predictive Mesoscale model of the erosion and profile development of soft rock shores , 2005 .

[2]  D. Delahaye,et al.  Geomorphology: from expert opinion to modelling. , 2002 .

[3]  D. Petley,et al.  Combined Digital Photogrammetry and Time‐of‐Flight Laser Scanning for Monitoring Cliff Evolution , 2005 .

[4]  R. B. G. Williams,et al.  Chalk Shore platform erosion in the vicinity of sea defence structures and the impact of construction methods , 2007 .

[5]  A. R. Clark,et al.  Investigation and Management of Soft Rock Cliffs , 2002 .

[6]  S. Costa,et al.  The gravel beaches in north-west France and their contribution to the dynamic of the coastal cliff/shore platform system , 2006 .

[7]  A. Trenhaile.  Modelling the effect of waves, weathering and beach development on shore platform development , 2005 .

[8]  S. Costa,et al.  Origine de la variabilité spatiale du recul des falaises crayeuses du nord-ouest du Bassin de Paris. L'exemple du littoral haut-normand (France). , 2003 .

[9]  C. Moses,et al.  Retreat of Chalk cliffs in the eastern English Channel during the last century , 2006 .

[10]  G. Müller,et al.  Effect of Cliff Shape on Internal Stresses and Rock Slope Stability , 2008 .

[11]  Methods for measuring shoreplatform micro-erosion; a comparison of the micro-erosion meter and the laser scanner , 2006 .

[12]  A. Trenhaile.  Modeling the effect of late Quaternary interglacial sea levels on wave-cut shore platforms , 2001 .

[13]  C. Moses,et al.  Soft copy photogrammetry to measure shore platform erosion on decadal timescales , 2008 .

[14]  D. Robinson,et al.  Sub-aerial weathering of chalk shore platforms during harsh winters in Southeast England , 1987 .

[15]  R. B. G. Williams,et al.  Temporal and spatial variations of chalk cliff retreat in East Sussex, 1873 to 2001 , 2008 .

[16]  A. Genter,et al.  Coastal cliff geohazards in weak rock: the UK Chalk cliffs of Sussex , 2004, Geological Society, London, Engineering Geology Special Publications.

[17]  L. Robinson.  Marine erosive processes at the cliff foot , 1977 .

[18]  C. So.  Coastal Platforms of the Isle of Thanet, Kent , 1965 .

[19]  A. Trenhaile.  Coastal dynamics and landforms , 1997 .

[20]  A. Genter,et al.  Coastal Rock Cliff Erosion by Collapse at Puys, France: The Role of Impervious Marl Seams within Chalk of NW Europe , 2002 .

[21]  A. Trenhaile.  Rock coasts, with particular emphasis on shore platforms , 2002 .

[22]  Guillaume Pierre,et al.  The retreat of chalk cliffs at Cape Blanc-Nez (France): Autopsy of an erosional crisis , 2003 .

[23]  V. May.  The Retreat of Chalk Cliffs , 1971 .

[24]  N. J. Porter,et al.  Patterns of surface downwearing on shore platforms in eastern Canada , 2010 .

[25]  S. Costa,et al.  The retreat of the chalk cliffs of the Pays de Caux (France): erosion processes and patterns , 2006 .

[26]  A. Trenhaile,et al.  A theoretical investigation of the Holocene development of rock coasts, with particular reference to shore platforms , 1986 .

[27]  A. Trenhaile.  Modeling the role of weathering in shore platform development , 2008 .

[28]  A. S. Trenhaile,et al.  Shore platforms: a neglected coastal feature , 1980 .

[29]  D. Delahaye,et al.  Quantification of the Normandy and Picardy chalk cliff retreat by photogrammetric analysis , 2004, Geological Society, London, Engineering Geology Special Publications.

[30]  N. J. Porter,et al.  Shore platform downwearing in eastern Canada: The mega-tidal Bay of Fundy , 2010 .

[31]  J. N. Hutchinson.  Chalk flows from the coastal cliffs of northwest Europe , 2002 .

[32]  Predicting rates of shore platform downwearing from rock geotechnical properties and laboratory simulation of weathering and erosion processes , 2006 .

[33]  A. Trenhaile.  Modeling the development of wave-cut shore platforms , 2000 .

[34]  D. Robinson,et al.  Frost and salt weathering of chalk shore platforms near Brighton, Sussex, U. K. , 1987 .

[35]  D. Petley,et al.  Terrestrial laser scanning for monitoring the process of hard rock coastal cliff erosion , 2005, Quarterly Journal of Engineering Geology and Hydrogeology.

[36]  C. Moses,et al.  Chalk coast erosion and its contribution to the shingle budget in East Sussex , 2006 .

[37]  A. Trenhaile.  The Geomorphology of Rock Coasts , 1987 .

[38]  J. S. Burn.  Henley-on-Thames , 1856 .

[39]  Illustrated London News刊行会.  The Illustrated London news , 1842 .

[40]  S. Costa,et al.  Le recul des falaises crayeuses du Pays de Caux : détermination des processus d'érosion et quantification des rythmes d'évolution , 2002 .

[41]  W. Stephenson,et al.  Decadal scale micro erosion rates on shore platforms , 2010 .

[42]  R. B. G. Williams,et al.  Limpet erosion of chalk shore platforms in southeast England , 2000 .

[43]  U. Dornbusch,et al.  Block removal and step backwearing as erosion processes on rock shore platforms: a preliminary case study of the chalk shore platforms of south‐east England , 2011 .

[44]  Kenneth O. Emery,et al.  Sea cliffs: Their processes, profiles, and classification , 1982 .

[45]  S. Taibi,et al.  Effect of groundwater and sea weathering cycles on the strength of chalk rock from unstable coastal cliffs of NW France , 2005 .

[46]  D. Robinson,et al.  Rates and patterns of downwearing of chalk shore platforms of the Channel Coasts: Comparisons between France and England , 2006 .

[47]  A. Trenhaile.  Predicting the response of hard and soft rock coasts to changes in sea level and wave height , 2011 .

[48]  A. Trenhaile.  Modeling the accumulation and dynamics of beaches on shore platforms , 2004 .

[49]  Guillaume Pierre,et al.  The role of groundwater in cliff instability: an example at Cape Blanc‐Nez (Pas‐de‐Calais, France) , 2006 .

[50]  A. Trenhaile.  The effect of Holocene changes in relative sea level on the morphology of rocky coasts , 2010 .

[51]  W. Stephenson.  Shore platforms: a neglected coastal feature? , 2000 .

[52]  Gloria Senfaute,et al.  Micro-seismic precursory cracks prior to rock-fall on coastal chalk cliffs: a case study at Mesnil-Val, Normandie, NW France , 2009 .