Preservation of a drowned gravel barrier complex: A landscape evolution study from the north-eastern English Channel

Mellett, Claire L.; Hodgson, David M.; Lang, Andreas; Mauz, Barbara; Selby, Ian; Plater, Andrew J.

doi:10.1016/j.margeo.2012.04.008

Cited by 67 publications

(61 citation statements)

References 62 publications

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“…Sediment protects the platform against vertical downwearing and serves to dissipate wave energy otherwise available to drive cliff erosion. Beaches within the study area are known to have been thinning during the Holocene (7), in part supplying the wider beaches to the east (downdrift) (31)(32)(33).…”

Section: Discussionmentioning

confidence: 99%

Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain

Hurst

Rood

Ellis

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

105

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Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the driving mechanisms of coastal change. Direct observations of cliff retreat rarely extend beyond 150 y, during which humans have significantly modified the coastal system. Cliff retreat rates are unknown in prior centuries and millennia. In this study, we derived retreat rates of chalk cliffs on the south coast of Great Britain over millennial time scales by coupling high-precision cosmogenic radionuclide geochronology and rigorous numerical modeling. Measured 10 Be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a Monte Carlo approach to determine the most likely history of cliff retreat. The 10 Be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow (2-6 cm·y −1 ) until a few hundred years ago. Historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude (22-32 cm·y −1 ). We suggest that acceleration is the result of thinning of cliff-front beaches, exacerbated by regional storminess and anthropogenic modification of the coast.geomorphology | coasts | cosmogenic radionuclides | erosion | cliffs R ocky coasts are "erosional environments formed as a result of the landward retreat of bedrock at the shoreline" (1). They leave scant evidence of any previous state, making it difficult to interpret their history. Cliff retreat is driven by a combination of wave-driven cliff-base erosion, subaerial weathering, and mass wasting processes, whose efficiencies are dependent on lithology and climate. Sediment generated by mass wasting processes such as abrasion, plucking, landslides, and rockfalls tends to be reworked and transported away by waves and currents, particularly for softer rock types.Cliff erosion due to mass wasting threatens livelihoods and both public and private clifftop infrastructure and development; quantitative estimates of the rate of cliff retreat are necessary to assess the associated risk. Rising sea levels and increased storminess may lead to accelerated coastal erosion rates in the future, potentially increasing hazard exposure (2-5). To accurately assess coastal hazards in the face of future climate and land-use changes, it is necessary to understand the dynamics of cliff erosion over length and time scales relevant to the processes that drive change. To establish the context for modern change, we must quantify the natural variability and the long-term behavior of cliff retreat. Historical records are too short to allow us to do this: they typically span no longer than ∼150 y (6, 7), which can be less than the characteristic return period of significant coastal failures (8), and they coincide with the period over which humans have significantly modified th...

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Section: Discussionmentioning

confidence: 99%

Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain

Hurst

Rood

Ellis

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

105

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“…Barrier-lagoon systems include the shoreface sector, the barrier and the back-barrier sector, where washover fans and lagoons develop (Mellett et al, 2012;Otvos, 2012).Their formation is related to the interplay between wave energy, sediment supply, accommodation space and rate of relative sea-level rise (Hesp and Short, 1999).…”

mentioning

confidence: 99%

“…Two basic models of barrier retreat under transgressive conditions were proposed: (i) the rollover model is generally considered the dominant retreat process, and involves a continuous migration of the barrier systems following the shoreline retreat, with the reworking of shoreface and barrier deposits and the absence of deposit preservation offshore (Swift and Moslow, 1982;Leatherman et al, 1983); (ii) the barrier retreat through overstepping involves a partial preservation of transgressive deposits or barrier morphology following a fast rate of sea-level rise (Rampino and Sanders, 1980Forbes et al, 1991;Storms et al, 2008;Mellett et al, 2012). In particular, gravel barriers are more likely to be preserved (Long et al, 2006;Mellett et al, 2012).…”

mentioning

confidence: 99%

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Early cementation and accommodation space dictate the evolution of an overstepping barrier system during the Holocene

et al. 2015

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“…Increased wave heights and the frequency of strong winds, especially in the North Atlantic to the north and west of the UK have been reported (Gulev and Hasse, 1999;Gulev and Grigorieva, 2004;Alexander et al, 2005;Hadley, 2009;Mellet et al, 2013). These changes can have significant impacts on the continental shelves, thereby making them and the adjoining coastlines to be susceptible to erosion, deposition, marine flora and fauna disruption, and other palaeoenvironmental change (Kelley et al, 2010;Mellet et al, 2012Mellet et al, , 2013. Detecting the bathymetry change of the coastal embayment is necessary in the understanding of the near-shore coastal marine environment morphodynamics.…”

Section: Introductionmentioning

confidence: 99%

Seabed dynamics in a coastal embayment

Oyedotun¹

2017

IER

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This study focuses on the morphological history of the seabed adjacent to the St. Ives to Padstow Bay coastlines, southwest England. 1931 and2008 bathymetric charts covering the North Cornwall coast were examined using bathymetric change maps and transects. The results here showed that the seabed topography in this region is not static, with patterns of net sediment movement varying spatially across the seabed. Rates of erosion and deposition varied because of the seabed exposure to the diverse rates of higher waves and tidal actions. The variation relates to the relative depths at which waves feel the seabed. Waves are more sensitive at nearshore bathymetry depths less than 20m (and 3.5km offshore) than at offshore. However, the amount of energy and increasing wave height reaching the coastlines have a minor impact on sediment transport rates or morphological modification of the adjacent coastlines and estuaries but allow the erosion potentials.Keywords: bathymetry; change detection; morphodynamics; coastal processes; SWAN; wave propagation; coastal zone; volumetric seabed change; shore-normal transects. Biographical notes: Temitope D. Timothy Oyedotun is an internationally recognised environmental researcher and university tutor. For the last 12 years, he has acquired and developed academic and research interests in diverse academic and research fields -principally in water resources management, river dynamics, fluvial geomorphology, quantitative and spatial analyses, geographic information systems (GIS) and, of recent, estuarine/coastal systems morphodynamics (coastal geomorphology). Years of international academic exposures and training have developed in him a culture of discipline with an ethic of academic entrepreneurship and great scholarship performance. He heads the Research and Concept Unit of AfriGeoServ, a consultancy firm he co-founded.

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Preservation of a drowned gravel barrier complex: A landscape evolution study from the north-eastern English Channel

Cited by 67 publications

References 62 publications

Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain

Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain

Early cementation and accommodation space dictate the evolution of an overstepping barrier system during the Holocene

Seabed dynamics in a coastal embayment

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