18: Shorelines
- Page ID
- 29175
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Summarize the factors that control wave formation and the important features of waves
- Explain how water is disturbed beneath a wave, and how that affects the behavior of waves as they approach the shore
- Describe the origins of longshore currents and longshore drift
- Explain why some coasts are more affected by erosion than others and describe the formation of coastal erosional features, including stacks, arches, cliffs, and wave-cut platforms
- Explain the process of coastal straightening
- Summarize the origins of beaches, spits, baymouth bars, tombolos, and barrier islands
- Describe the origins of carbonate reefs
- Explain the various mechanisms of sea-level change (eustatic, isostatic, and tectonic) and the implications for coastal processes
- Compare the positive and negative implications of human interference with coastal processes
- 18.1: Waves
- This page explores the generation of waves on water bodies by wind and their interaction with the shore. It details how wind factors affect wave characteristics and describes the effects of waves as they approach the coast, leading to breaking and longshore currents that impact sediment transport. The page further discusses longshore drift and dangerous rip currents, as well as the role of tides in coastal ecosystems, particularly highlighting their impact on features like the Bay of Fundy.
- 18.2: Landforms and Coastal Erosion
- This page discusses the erosion of rocky shores by large waves, particularly at headlands where wave refraction intensifies energy, leading to coastal straightening over time. Erosion in the surf zone forms wave-cut platforms and can create features like arches and sea caves. Over time, irregular coastlines transform into straightened coasts with sea cliffs, stacks, and platforms, ultimately resulting in continuous coastlines shaped by the availability of sand.
- 18.3: Landforms and Coastal Deposition
- This page discusses the shaping of coastal areas through erosion and deposition, influenced by tectonic activity and sediment supply. It contrasts the erosion-dominated Pacific coast with the deposition-dominant Atlantic coast. Seasonal changes affect beach dynamics, with summer adding sand and winter eroding it. Key coastal features like spits and barrier islands are highlighted, along with the role of carbonate reefs in tropical regions, contributing to unique sedimentary environments.
- 18.4: Sea-Level Change
- This page explains the mechanisms of sea-level change, including eustatic (global shifts due to glacial ice volume and seafloor changes), isostatic (local crustal adjustments post-ice melting), and tectonic (local geological processes like subduction). It highlights a notable eustatic rise of approximately 125 m over 20,000 years from glacial melting and how these processes impact coastal features like fjords and uplifted platforms.
- 18.5: Human Interference with Shorelines
- This page examines human modifications to shorelines, including seawalls, rip-rap, and groynes, which aim to control erosion. While these structures can provide recreational areas and protect properties, they may also cause ecological harm, such as habitat loss and sediment starvation in nearby regions. The page highlights the critical need for managing sediment flow from rivers, noting that damming can reduce beach nourishment and heighten erosion risks along adjacent coastlines.
- 18.6: Chapter 18 Summary
- This page explores waves and coastal processes, detailing their formation, erosion, and deposition. It highlights the influence of wind on wave size and behavior in shallow waters. The chapter differentiates between the impacts on irregular and straight coasts, emphasizing features like beaches and barrier islands. It also covers the effects of sea-level changes and human activities on shorelines, discussing potential geological and ecological consequences.