formation of coastline

FORMATION OF COASTLINEName :- Leena .R. MeenaSemester :- 3Roll no. :- 4Department of Marine Science

Coast line

Introduction

Definition

FormationBeache

sCoastal features

Types of Coast

Classification of Coast

Importance of Coast

Human Impact

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Discovery

INTRODUCTION Coast are often highly abundant natural resources. The majority of world’s population live close to sea. As many as 3 billion people live within 60 km of the shoreline. The coast plays an important role in global transportation, and is the destination of many of the world’s tourists. The surface of ocean is set in motion by action of winds blowing across it.

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DISCOVERY

Several attempts have been made to classify shorelines but the most universally accepted scheme was proposed by Franchis P. Shepard I 1937 and revised slightly in 1963.

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COAST LINE ????

The boundary of a coast, where land meets the sea, is called the coastline.

Edge of land along the sea or other large body of water.

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FORMATION OF COASTLINE ??

1. Waves, tides, and currents help create coastlines.

2. The energy of waves moving onshore enables them to deposit sediments

obtained through wave erosion to form the most common deposited feature,

the beaches.

3. All coastal features are classified the result of either wave erosion or wave

deposition.

4. Sedimentation or wave deposition always occur parallel to shoreline. 6

BEACHES

• Beaches are formed by sediments which are transported by waves and tides and piled up along the shore.

• The sediment found on the beaches are transported by wave energy by back and forth in rhythm to the movement of swash and backwash.

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8Cross section of idealized beach

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• The beaches are observable features changing from season and in some places daily.

• Beaches are composed of sediments according to size known as sand, and according to the geologist’s scale of sediments sizes called the Wentworth scale.

10Table :- Wentworth Scale of Particle Sizes for Sediments

COASTAL LANDFORMS

Coastal landforms, any of the relief features present along any coast, the result of a combination of processes, sediments, and the geology of the coast itself.

There are many factors and forces in the formation of coastal features.

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FACTORS AND FORCES IN THE FORMATION OF

COASTAL FEATURES

• The landforms that develop along the coast are the result of a combination of processes acting upon the sediments and rocks present in the coastal zone.

• The most common of these processes involves waves and the currents that they generate, along with tides.

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Factors in formation of coastal feature

Waves

Tides

Rip Current

Longshore current

Climate change

Rainfall

Temperature

Wind

Gravitational

FACTORS AND FORCES IN THE FORMATION OF COASTAL FEATURES

Waves

• The most obvious of all coastal processes is the continual motion of the waves moving toward the beach.

• Waves interact with the ocean bottom as they travel into shallow water; as a result, they cause sediment to become temporarily suspended and available for movement by coastal currents.

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LONGSHORE CURRENTS• The movement of sediment along the coastline is called longshore

drift.

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swas

h

Back

wa

sh

Longshore Transport

RIP CURRENT• Another type of coastal current caused by wave activity is the rip

current.

• As waves move toward the beach, there is some net shoreward transport of water. This leads to a slight but important upward slope of the water level.

• Water moves seaward through the surf zone in an effort to relieve the instability of the sloping water.

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Tides

• The rise and fall of sea level caused by astronomical conditions is regular and predictable. There is a great range in the magnitude of this daily or semi-daily change in water level.

• Tidal currents transport sediment in the same way that longshore currents do.

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ClimateClimate is an extremely important factor in the development of coastal landforms. The elements of climate include rainfall, temperature, and wind.

RainfallRainfall is important because it provides runoff in the form of streams and also is a factor in producing and transporting sediment to the coast. This fact gives rise to a marked contrast between the volume and type of sediment

TemperatureTemperature is important for two quite different reasons. It is a factor in the physical weathering of sediments and rocks along the coast and in the adjacent drainage basins. This is particularly significant in cold regions where the freezing of water within cracks in rocks causes the rocks to fragment and thereby yield sediment.

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WindWind is important primarily because of its relationship to waves. Coasts that experience prolonged and intense winds also experience high wave-energy conditions

GravityGravity, too, plays a major role in coastal processes. Not only is it indirectly involved in processes associated with wind and waves but it also is directly involved through downslope movement of sediment and rock as well.

The coastal environment of the world is made up of a wide variety of landforms manifested in a spectrum of sizes and shapes ranging from gently sloping beaches to high cliffs, yet coastal landforms are best considered in two broad categories:

Erosional

Depositional

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LANDFORMS OF EROSIONAL COASTSThere are two major types of coastal morphology: one is dominated by erosion and the other by deposition. Erosional coasts are those with little or no sediment.

These coasts are dominated by exposed bedrock with steep slopes and high elevations adjacent to the shore.

The type of rock and its lithification are important factors in the rate of erosion.

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EROSIONAL COASTS

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SEA CLIFFS

WAVE-CUT PLATFORMS

SEA STACKS

SEA ARCHES

24Sea Cliff

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WAVE-CUT PLATFORMS

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Sea Stack, Mount Taranaki, North Island, New Zealand

SEA ARCHES

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LANDFORMS OF DEPOSITIONAL COASTS

Depositional coasts are characterized by abundant sediment accumulation over the long term. Both temporal and geographic variations may occur in each of these coastal types.

Coasts adjacent to the trailing edge of lithospheric plates tend to have widespread coastal plains and low relief.

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DEPOSITIONAL COAST

Depositional coasts can be described in terms of three primary large-scale types:

Deltas

Barrier island/estuarine systems

Strand-plain coasts

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DELTAS

India and Bangladesh - sunderbans

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BARRIER ISLAND

ESTUARY SYSTEM

STRAND-PLAIN COASTS• Some wave-dominated coasts do not contain estuaries and have no

barrier island system. These coasts, however, do have beaches and dunes, and may even have coastal marshes.

32Beaches

Coastal Dunes Coastal Marshes

DEVELOPMENT AND CLASSIFICATION OF COASTLINES

There are two possible types of changes in level of the sea.

either the water level itself will rise or fall.

land uplifted or depressed.

In respect to development processes of coastline, it has two methods of formation :-

Terrestrial processes

Marine processes

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CLASSIFICATIONOn the basis of mode of formation of coast shepard classify it in two types :- Primary Coastline - land based agencies.

Secondary Coastline – marine factors

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Fjord

Glaciers

Valley

Beaches

Mud flat

REFERENCE• Introductory Oceanography by Joseph Weisberg and Howard Parish

• Coast by Colin D. Woodroffe

• National geography.org

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