Geography
Coastal Deposition Landforms
Coastal deposition landforms are created by the accumulation of sediment along the coast. These landforms include beaches, spits, tombolos, and barrier islands. They are formed by the action of waves, currents, and tides, and are important features of coastal ecosystems and human settlements.
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11 Key excerpts on "Coastal Deposition Landforms"
eBook - PDF- Timothy Foresman, Alan H. Strahler(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
2. Describe thedepositionallandformsproduced bywaves. 3. Define coastlinesofsubmergence. 4. Explain thefeaturesofcoralreefs. coastline(coast) The zone in which coastal processes op- erate or have a strong influence CoastalLandforms409 by as much as 125 m (410 ft). Rivers cut canyons to depths well below present sea level to reach the ocean. Waves broke against coastlines that are now well underwater. Now that sea level has risen, many coastal landscapes are coastlines of submergence. Still other coastlines are dominated by coral reefs, where ocean waters are warm enough for coral to grow. Erosional Coastal Landforms The breaking of waves against a shoreline provides a va- riety of distinctive features. Where resistant rocks meet the waves, sea cliffs often oc- cur. At the base of a sea cliff is a notch, formed largely by physical weathering. Constant splashing by waves followed by evaporation causes salt crystals to grow in tiny crevices and fissures of the rock, breaking it apart, grain by grain. Hydraulic pressure of waves and abrasion by rock fragments thrust against the cliff also erode the notch. Undercut by the notch, blocks fall from the cliff face into the surf zone. As the cliff erodes, the shoreline gradually retreats shoreward. Sea cliff erosion forms a variety of ero- sional landforms, including sea caves, sea arches, and sea stacks (Figure 13.18). zone in which waves perform their work, as well as the landforms they create. In contrast, the shoreline refers to the dynamic zone of con- tact between water and land. The Earth’s coastlines are enormously varied. For ex- ample, along most of the east coast of the United States, we find a coastal plain gently sloping toward the sea, with shallow lagoons and barrier islands at the coastline. On the west coast, we often find rocky shorelines, with dra- matic sea cliffs, headlands, and pocket beaches. Plate tectonics provides a way to explain these dif- ferences.
eBook - PDF- James Petersen, Dorothy Sack, Robert Gabler, , James Petersen, Dorothy Sack, Robert Gabler(Authors)
- 2014(Publication Date)
- Cengage Learning EMEA(Publisher)
Sand-sized sediment eroded from the beach in winter forms a deposit called a longshore bar that lies submerged parallel to shore, with the sediment returning to the beach in summer. On the Atlantic and Gulf coasts of the United States, the late summer to early fall hurricane season is also a time when beach erosion can be severe. Beaches are attached to the mainland along their entire length; spits are coastal depositional landforms connected to the mainland at just one end ( ■ Fig. 17.17). Spits project out into the water like peninsulas of sediment. They form where the mainland curves significantly inland while the trend of the longshore current remains at the original orientation. Sedi-ments accumulate into a spit in the direction of the longshore current ( ■ Fig. 17.18a). Where similar processes deposit a strip of sediment connecting the mainland to an island, the land-form is a tombolo (Fig. 17.18b). Another category of coastal landforms are barrier beaches , elongate depositional features constructed parallel to River Delta Lagoon Baymouth barrier Tombolo Spit Ocean or lake ■ FIGURE 17.17 Some of the major landforms found along deposition-dominated coastlines. How is a tombolo different from a spit? © Cengage Learning Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. C H A P T E R 1 7 • C O A S TA L P R O C E S S E S A N D L A N D F O R M S 464 ■ FIGURE 17.18 (a) A spit is attached to the mainland at one end. (b) A tombolo connects a nearby island with the mainland. (c) A baymouth barrier crosses the mouth of an embayment connecting to land at both ends.
No longer available |Learn more- James Petersen, Dorothy Sack, Robert Gabler(Authors)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
■ 20.5 Recount how sediment moves along a beach. ■ 20.6 Identify coastal erosion processes and the primary landforms found on erosion-dominated coastlines. ■ 20.7 Describe the types and sources of sediment found in coastal depositional landforms. ■ 20.8 Distinguish among the principal coastal depositional landforms. ■ 20.9 Summarize a global-scale and a regional-scale classification of coasts. ■ 20.10 Describe the different types of coral reef. OBJECTIVE WHEN YOU COMPLETE THIS CHAPTER YOU SHOULD BE ABLE TO: OUTLINE The Coastal Zone Origin and Nature of Waves Tides Tsunamis Geography’s Physical Science Perspective: Tsunami Forecasts and Warnings Wind Waves Breaking of Waves Coastal Geomorphic Processes Wave Refraction and Littoral Drifting Coastal Erosion Coastal Deposition Types of Coasts Geography’s Environmental Science Perspective: Beach Protection Islands and Coral Reefs Change over Time Map Interpretation: Active-Margin Coastlines Map Interpretation: Passive-Margin Coastlines COASTAL PROCESSES AND LANDFORMS 20 ▼ The shorelines of the world are extensive, complex, and often spectacular environments. David Crosbie/Alamy Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. C H A P T E R 2 0 • C O A S T A L P R O C E S S E S A N D L A N D F O R M S 572 warming significantly reduces the extent of the continental ice sheets, the ensuing rise in sea level will have a profound impact on the human-built infrastructure in coastal regions and on coastal geography and geomorphology.
eBook - PDF- James Petersen, Dorothy Sack, Robert Gabler, , James Petersen, James Petersen, Dorothy Sack, Robert Gabler(Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
Most of it is delivered to the standing body of water by streams. At its mouth, the load of a stream may be deposited for the long term in a delta or within an estuary, a biologically very productive embayment that forms at some river mouths where salt and fresh water meet. Elsewhere, stream load may instead be delivered to the ocean or lake for continued transportation. Once in the standing body of water, fine-grained sediments that stay in suspension for long periods may be carried out to deep water where they eventually settle out onto the basin floor. Other clasts are transported by waves and currents in the coastal zone, being deposited when energy decreases and, if accessible, reentrained when wave energy increases. The same is true of the second major source of coastal sediment, coastal cliff erosion. Of less importance is sediment brought to the coast from offshore sources. Although we may tend to think of sand-sized sediment when we think of coastal deposits, coastal depositional land- forms may be composed of silt, sand, or any size classes of gravel, from granules and pebbles through cobbles and boulders. The most common landform of coastal deposition is the beach, a wave-deposited feature that is contiguous with the mainland throughout its length (● Fig. 20.18). Many beaches are sandy, but beaches of other grain sizes are also common, as for for removal by wave erosion. Water is a key element in most weathering processes, and in addition to normal precipitation, rocks near the shoreline are subjected to spray from breaking waves, high humidities, and condensation. Salt weathering is particularly significant in preparing rocks for removal through chemical and physical weathering along the marine coast and coasts of salt lakes. Coasts of high relief are dominated by erosion (● Fig. 20.15). Sea cliffs (or lake cliffs) are carved where waves pound directly against steep land.
eBook - PDF- Tom Garrison, Robert Ellis(Authors)
- 2017(Publication Date)
- Cengage Learning EMEA(Publisher)
Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 153 8 Coasts KEY CONCEPTS The location of a coast depends on global tectonic activity and the ocean’s water volume. The shape of a coast is a product of uplift and subsid-ence, the wearing down of land by erosion, and the redistribution of material by sediment transport and deposition. Coasts may be classified as erosional coasts (on which erosion dominates) or depositional coasts (on which deposition dominates). Beaches change shape and volume as a function of wave energy and the balance of sediment input and removal. Human interference with coastal processes has generally accelerated the erosion of coasts near inhabited areas. Coasts are places of rapid change, tenacious organisms and often great beauty. The northern California coastline along Big Sur is a stunning example of the complexity that can occur at the land and sea interface. Lynn Y/Shutterstock.com Post-Glacial Sea Level Rise 20 18 0 12 6 0 14 8 4 16 10 2 Thousands of years ago 00 50 50 25 75 75 Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 CHAPTER 8 154 8.1 Coasts Are Shaped by Marine and Terrestrial Processes Coastal areas join land and sea. Our personal experience with the ocean usually begins at the coast. Have you ever wondered why a coast is shaped as you see it? These temporary, often beautiful junctions of land and sea are subject to rearrange-ment by waves and tides, by gradual changes in sea level, by biological processes, and by tectonic activity. The place where ocean meets land is usually called the shore , and the term coast refers to the larger zone affected by the processes that occur at this boundary.
eBook - PDF- Alan H. Strahler(Author)
- 2013(Publication Date)
- Wiley(Publisher)
Marine terraces are common along the continental and island coasts of the Pacific Ocean, where tectonic processes are active along the mountain and island arcs. DEPOSITIONAL COASTAL LANDFORMS Most of the sediment we find along a coastline is provided by rivers that reach the ocean. Waves then transport and deposit this sediment to take shape as shoreline features such as beaches, bars, and spits. These depositional landforms are relatively transitory, how- ever, appearing, disappearing, or migrating as a result of seasonal changes, storms, and human engineering. Beaches A beach is a wedge-shaped sedimentary deposit, usually of sand, built and worked by wave action. The face of a beach varies over time as waves either deposit or erode more sand. During short periods of storm activity, waves cut back the beach, giving it a long, flat, sloping profile. The sand moves just offshore and along the shore via longshore drift. Gentler waves return the sand to the beach, building a steeper beach face and a bench of sand at the top of it. When sand leaves a section of beach more rap- idly than it is brought in, the beach is narrowed and the shoreline moves landward. Conversely, when sand arrives at a particular section of the beach more rap- idly than it is carried away, the beach is widened and Waves erode weak materials, resulting in marine scarps, and weather resistant rocks, which are reshaped as marine cliffs. Caves, arches, stacks, and abra- sion platforms are land- forms of marine cliffs. University of Washington Libraries, Special Collections, John Shelton Collection, KC8974 Marine terrace Former sea level Former sea cliff 16.17 Marine terraces Marine terraces give us a visual record of coastlines and sea levels from the Earth’ s past. UPLIFT FORMS A TERRACE After a period of tectonic uplift or lowered sea level, the shore platform at the base of the cliffs is raised up to become a marine terrace.
eBook - PDF- Alan F. Arbogast(Author)
- 2017(Publication Date)
- Wiley(Publisher)
437 CHAPTER 19 CHAPTER PREVIEW Oceans and Seas on Earth The Nature of Coastlines: Intersection of Earth’s Spheres Tides Coastal Landforms Waves and Coastal Erosion Longshore Processes and Depositional Coastlines Human Interactions with Coastlines Evolution of the Louisiana Coastline Coastal Processes and Landforms The previous three chapters investigated fluvial, glacial, and eolian processes and their distinctive landforms. Now we turn to the various processes and landforms that occur along coastlines. Although these processes affect a very small part of the Earth’s surface, they create some of the most distinctive and popular landscapes you see. Why should you be interested in coastal processes and landforms? One important reason is that you may very well live along or near a coast- line, as do a majority of people in the United States (and indeed, the world). People are attracted to coastlines for a variety of economic, recreational, and lifestyle reasons and are affected by the geomorphic processes that occur along these narrow strips of land. In turn, people influence the behavior of coastlines in dramatic ways through development. Thus, understanding the geomorphology of coastlines is important, not only for gaining a better appreciation of this landscape, but also for becoming a good steward for these areas. James Morgan/Robert Harding World Imagery/Getty Images Are you attracted to this landscape? If so, you are certainly not alone. Coastlines are perhaps the most exotic landscapes on Earth, and people love to live near or visit them. This chapter focuses on the oceans of the world and the way they shape the landscape along coastlines. 438 CHAPTER 19 Coastal Processes and Landforms Oceans and Seas on Earth Before we begin discussing various coastal processes, let’s take a closer look at the character of the world’s oceans and seas because it provides the context in which to view the shore.
eBook - PDF- Mateo Gutierrez(Author)
- 2012(Publication Date)
- CRC Press(Publisher)
11 COASTAL GEOMORPHOLOGY 1. Introduction 2. Brief history of coastal geomorphology 3. Temporal and spatial scales 4. Sea level variations 5. Waves, currents, and tides 6. Cliff coasts and rocky platforms 7. Coral reef coasts 8. Beaches, barriers, and spits 9. Coastal dunes 10. Mudflats, salt marshes, and mangroves 11. Estuaries and deltas 12. Coastal environments: Uses, management, and risks 11.1 Introduction Bird (2000) defines coastal geomorphology as the study of the evolution of coastal landforms, the processes that affect them, and the changes they undergo. These landforms include cliffs, rocky coastal margins, beaches, dunes, estuaries, lagoons, and deltas. The world’s coastal margins are about 100 m wide and 440,000 km long; humans use them for industrial pur- poses, transportation, and recreation. These human activities profoundly impact these areas. The United Nations estimates that 66% of the world’s population lives within a few kilom- eters of the coast (Pethick, 1984). As a result, food produc- tion, communication, cities, and recreational areas all affect the coast. Coasts have significant problems that include flood- ing, erosion, pollution, and sea level variations that require constant attention. Interdisciplinary studies by coastal engi- neers, oceanographers, and geomorphologists have led to significant advances in coastal management (Stephenson and Brander, 2003). In addition, coasts are constantly changing; the change may be catastrophic or imperceptible. Modifica- tions may occur over decades or centuries but they can also take place in a period of hours or minutes. 11.2 Brief history of coastal geomorphology Prior to the 20th century, research on coastal geomorphology was limited to engineering topics related to coastal erosion (Walker and MacGraw, 2005). Charles Darwin made impor- tant observations on coral reefs and the origin of atolls during his famous voyage on the British ship, the Beagle, in 1835 (Shepard, 1959).
eBook - PDFPhysical Geology
The Science of Earth
- Charles Fletcher(Author)
- 2017(Publication Date)
- Wiley(Publisher)
Understanding how coastal processes and sedimentary materials interact is crucial to inter- preting the geologic history of coastal systems and finding ways for people to live in the coastal zone in a sustainable manner. Coastal Terminology Scientists employ a number of specific terms when describing the coastal zone. Here, we focus on beaches because that is where we can most readily observe the processes associated with waves; but the concepts that apply to beaches apply to other types of coastal environments as well (Figure 20.3). A beach is an unconsolidated accumulation of sand and gravel along the shoreline. In this discussion we emphasize the beaches most familiar to many, those that develop along the shores of oceans; but beaches also form in freshwater environ- ments such as lakes and rivers. FIGURE 20.3 The coastal zone consists of several environments in which sediments, waves, and currents interact to produce coastal processes. Swash zone Foreshore Backshore Inshore Plunging breakers Berm Dune Run-up Bore Bar Mean sea level Offshore Surf zone Breaker zone What kind of sediments collect on beaches? Where do they come from? 616 CHAPTER 20 Coastal Geology Concept Check 20.1 Please complete this exercise before coming to class. Identify the best answer to each question. 1. The coastal zone is constantly changing because: a. Waves and currents are constantly shifting the position of sand and other sediments. b. Storms frequently strike the shore. c. Sea level rises and falls through time, changing the location of the shoreline. d. Humans influence coastal environments. e. All of the above.
eBook - PDF- David Huddart, Tim A. Stott(Authors)
- 2019(Publication Date)
- Wiley-Blackwell(Publisher)
They can form over extensive areas; for example in the Philippines and south‐west Florida they can form coastal strips over 20 km wide. The principal differ- ence between these swamps and the salt marshes of more temperate latitudes is the increased amount of organic matter involved. 19.5.3 River‐dominated Coastal Landforms In areas of limited tidal range with restricted wind and wave regimes, or where sediment supply is very high, a coast may become dominated by a strong fluvial influence. In most cases, this is shown by the development of a delta. A delta is a mass of fluvial sediment extending out from a shoreline into a water body and as sediment is delivered to the river mouth it is deposited and builds seawards. Deltas are com- plex and may contain a bewildering range of sedi- mentary environments, which collectively form a prograding package of sediment. Deltas form whenever the current velocity of a river is checked by flow into a standing water body and can occur on a micro‐scale in puddles, lakes, enclosed seas, estuaries, coastal lagoons and more exposed coasts, wherever the rate of sediment sup- ply exceeds the rate of removal by the action of wave or tidal currents. Within a river, sediment usually moves in traction along the bed and as suspended sediment. As a river discharges into the sea, the velocity is reduced rap- idly by the standing water, leading to bedload depo- sition. The rate at which this process occurs is a function of the inertia or ability of the river water to continue to flow seaward before it slows (dependent primarily on discharge and river gradient or stream power) and of frictional retardation of river water by the channel and sea floor (determined by water depth and both coastal and fluvial configurations). The behaviour of the suspended sediment is more complex and is dependent on the density, deter- mined by sediment concentration, salinity, and tem- perature, of the river water relative to that of the sea.
eBook - PDFPhysical Geography
Great Systems and Global Environments
- William M. Marsh, Martin M. Kaufman(Authors)
- 2012(Publication Date)
- Cambridge University Press(Publisher)
9 Describe the three-step process of bank erosion. How are bedrock and softer shorelines eroded, and what shoreline features result in each setting? 10 What are sediment sources and sediment sinks and how are they linked together to form a system? What name is give to such systems and what does it mean if a system has a large net sediment transport value? 11 What explains the occurrence of deposition zones or sites, along a shoreline? Using Figure 22.25, identify the landforms associated with these sites: coastal island, mouth of a bay, head of a bay, and explain why they formed there. 12 At the global scale, how do plate tectonics influence coastline development? What are the differences between active and passive coasts in terms of their formative processes and landforms? 13 Using Figures 22.31 and 22.32 as a guide, identify the primary landforms associated with emergent and submergent coasts. What are the distinct roles of plate tectonics, glaciation, and deposition within each type of coast? 14 Name three structures commonly used in coastal engineering, what they are designed to do, and the nature of the problems they often create. 15 In the 21st century struggle between humanity and the sea, the outcomes will be different for different countries. Discuss several of the factors that will shape these outcomes. Glaciers have became media causes celebres because they are considered harbingers of a changing global climate, and rightly so. To form and survive, glaciers need cold temperatures and plenty of snow, and when one or both of these changes on an established glacier, it grows or shrinks, and lately glaciers the world over have been shrinking not because of too little snow but because of warmer temperatures. And when we look back over the past two million years or so in Earth history, we find concrete evidence of distinct patterns of glaciers growing and shrinking in response to changes in climate.
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