Coastal Erosion Landforms
Coastal erosion landforms are physical features created by the gradual wearing away of coastal areas by natural forces such as waves, currents, and wind. Examples of coastal erosion landforms include sea cliffs, wave-cut platforms, and sea arches. These landforms are constantly changing due to the dynamic nature of coastal erosion processes.
5 Key excerpts on "Coastal Erosion Landforms"
eBook - ePub- Simon Bell(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...The composition of the rock, whether soft and easily eroded or hard and resistant, or the manner and direction of its bedding, partly determine the pattern of the coastline and the character of its structures. Tilted bedding of larger rocks of different types and strengths may result in a series of ridges containing rock pools, whilst horizontal bedding can lead to vertical cliffs. Weaknesses in some rock layers leads to undercutting and collapse, leaving stronger sections, which are then eroded further. The pressure of water and air in the waves thrown against cliffs helps to erode concave sections into caves. The intervening convex sections can become promontories and are eventually eroded away by the expansion of the caves (Figure 6.11). Lower strata may erode leaving higher sections intact and producing arches or natural bridges, which subsequently collapse leaving a rock tower or stack out at sea. The coastal edge thus describes a series of meandering shapes while the development of bays and promontories relates to aspects of explosion patterns and their outward spread, as described in Chapter One. All this leads to the highly fractal nature of coastlines with many microhabitats between high and low water for marine wildlife to use. The diversity displayed by the range of sizes of coastal structures and the habitats created by the different rock types and evolving structures make these some of the most aesthetically attractive landscapes. Their wildness, the force of the elements (wind, waves, tides and storms) also make it a dynamic landscape. Artists have always been drawn to coastal landscapes. Even in heavily urbanized areas, coasts give an immediate sense of wildness and closeness to wilful and uncontrolled nature, so that sublime emotions can be felt...
- Gerd Masselink, Michael Hughes, Jasper Knight(Authors)
- 2014(Publication Date)
- Routledge(Publisher)
...Together, they make up coastal barriers and these landforms can be considered the main depositional elements of wave-dominated coasts. The shoreface is the upper part of the continental shelf that is affected by contemporary wave processes and can be described by the equilibrium shoreface profile. Most net sediment transport on the shoreface takes place by waves and currents. Factors affecting shoreface sediment transport are wave asymmetry and the presence of bedforms. • The planform shape of wave-dominated coasts is strongly controlled by wave refraction. Swash-aligned coasts are oriented parallel to the crests of the prevailing incident waves (e.g. equilibrium bays), while drift-aligned coasts are oriented obliquely to the crest of the prevailing waves (e.g. spits). • Beaches are wavelain deposits of sand or gravel found along marine, lacustrine and estuarine shorelines. Beach morphology is highly variable with smaller-scale features such as beach cusps, nearshore bars and rip channels often present. The assemblage of these features and the morphodynamic process regime (reflective versus dissipative) allows beaches to be classified into distinct types. • Barriers are elongated, shore-parallel sand bodies that extend above sea level. Barrier morphology is affected by sea level, sediment supply, substrate gradient, geological inheritance, wave energy, tides and wind. Sea level and sediment supply are the most important factors influencing barrier evolution and morphology. Depending on the combination of these two factors barriers may be prograding, stationary or retrograding. • Management of the shoreface, beaches and barriers is based on an understanding of their physical processes. Hard and soft engineering strategies are often used to reduce shoreline erosion and maintain sediment volume. Both strategies are somewhat effective but can be associated with negative consequences, as by reducing longshore sediment transport...
eBook - ePubThe Early Anglo-Saxon Kingdoms of Southern Britain AD 450-650
Beneath the Tribal Hidage
- Sue Harrington, Martin Welch, Martin Welch(Authors)
- 2014(Publication Date)
- Oxbow Books(Publisher)
...4. Travelling and Using the Land- and Sea-Scapes Coastal erosion and tide patterns In the context of the environmental circumstances of the period AD 450–700, it is important to delineate the potentialities of coastal routeways as they impacted on Early Anglo-Saxon site location and landscape syntax. The coastline of southern England as it exists today was probably broadly in place 3000 years ago (c. 1000 BC) with localised variations thereafter caused by erosion and deposition related to tide and weather patterns. Where different geological formations form the coast, they erode at different rates. Modern estimates suggest that, for the study region’s south coast, the erosion rate will have varied between 28 metres and 108 metres per hundred years. Thus, for example, between Selsey Bill and the mouth of the Cuckmere in East Sussex, the coastline in AD 400 may have been over 1700 metres further out (Goudie and Brunsden 1994, 48, fig. 33). The coast of the Isle of Thanet and north Kent has lost land to a similar extent with estimates of up to 4.8 kilometres for the same period (Brookes 2007, 44). Between Folkestone and Dungeness in southeast Kent, however, the loss seems to have been far less, estimated at approximately 400 metres. There are two consistent factors in coastal formation (Cresswell 1959): tide rotation and wave fetch. Wave fetch refers to the distance a wave travels before it hits the shoreline and, as Figure 12 (derived from Cresswell 1959, 21) shows, the greatest impact is of the Atlantic Ocean onto the west coast of the British Isles. Correspondingly, the shortest fetches occur across the Irish Sea and along the English Channel. The North Sea is an area of medium fetch, with the break point between this and the short-fetch waves of the English Channel found around the North Foreland in Kent, indicating contrasting maritime conditions along each of these coasts...
eBook - ePubApplied Geomorphology
Binghamton Geomorphology Symposium 11
- Richard G. Craig, Jesse L. Craft, Richard G. Craig, Jesse L. Craft(Authors)
- 2020(Publication Date)
- Routledge(Publisher)
...11 EROSION HAZARDS ALONG THE MID-ATLANTIC COAST Robert Dolan, Bruce Hayden, Suzette K. May, and Paul May ABSTRACT Through analyses of historical changes in the shoreline and overwash zone (storm-surge penetration zone) along 630 km of the mid-Atlantic coast, we have determined that there are along-the-coast patterns of the rates of change of the shoreline. These arcuate patterns are present both before and after the passage of severe storms and are persistent through time. Severe storms do not result in a total restructuring of the shore zone. Like most natural systems, coastline processes and coastline forms are organized in both time and space, so high hazard zones are predictable from a probabilistic standpoint. Based on our studies this predictability extends down in scale to just a few hundreds of meters along the coast. INTRODUCTION Hurricanes and severe winter storms are responsible for frequent shore-zone changes along the mid-Atlantic coast barrier islands. In addition to physical and ecological modifications, private land holdings are often destroyed, communication and transportation facilities are disrupted, and loss of life is not uncommon (Fig. 1). Storm damage is superimposed on the longer-term trends of erosion and accretion that are related to sea-level variations (Hicks & Crosby 1975), the supply of sediment to the coast (Wolman 1971), secular changes in wave climate (Hayden 1975), and human alterations of the shoreline (Dolan 1972). In spite of an obvious long-term trend of shoreline recession and the effects of periodic storms, with few exceptions coastal zone planning and development have been based on the concept that the shoreline is stable or that it can be engineered to remain stable. Understanding the natural dynamics of barrier islands is essential to recognizing and estimating both the short-term and long-term hazards of living on them...
eBook - ePubThe Beach in Anglophone Literatures and Cultures
Reading Littoral Space
- Ursula Kluwick, Virginia Richter(Authors)
- 2016(Publication Date)
- Routledge(Publisher)
...Chapter 3 ‘Gripping to a wet rock’: Coastal Erosion and the Land-Sea Divide as Existentialist/Ecocritical Tropes in Contemporary British and Irish Fiction Anne-Julia Zwierlein Coastal Erosion: British and Irish Coastlines under Threat ‘Living on the Edge’ (Nicolson); ‘The Owners Whose Homes Are Going over a Cliff’ (Fryer); ‘I can’t even relax in bed as I’m certain that it will go in the middle of the night’ (Akwagyiram): these are just some samples from UK media coverage of the threat of coastal erosion at the onset of the twenty-first century. Through their dramatic staging of the physical processes of erosion along with their human consequences, these articles become, in a quite literal sense, what Kerridge in the Routledge Green Studies Reader has termed ‘ecothrillers: environmental cliffhangers’. In 2010, the Environment Agency, a non-departmental public body responsible to the UK Secretary of State for Environment, Food and Rural Affairs, published new long-term predictions until the year 2110 for coastal erosion along the British and Irish coastlines, along with interactive maps which allow users to zoom in on erosion zones in their local area and watch the predicted development over three timescales (see ‘Coastal Erosion Maps’). Coastal erosion is caused by factors such as the hydraulic action of waves, abrasion and attrition (see ‘Coastal Erosion’). While the phenomenon had been documented throughout history, scientific investigations into erosion proliferated with the advent of nineteenth-century geology, most famously in Lyell’s chapter on the ‘Action of the Sea on the British Coast’ from his Principles of Geology, and arguably, the natural process itself has recently accelerated on many stretches of the British and Irish coastline due to climate change. For a sizeable number of people who settled near cliffs once thought safe, worries over coastal erosion have become very serious indeed...
