Coastlines determine the perimeter of a country, state, island, or city. They also form beaches.

2,914 Questions
Oceans and Seas
Erosion and Weathering

Why does the coastline change?

Erosion due to wave action and high/low tides.

Ocean Tides

What do you call unusually high and low tides?

in England we call them spring tides and they occur whenever there is a full moon.

Natural Disasters

How do tsunamis happen?

A tsunami (Japanese for harbor wave) can be caused when a large volume of water in a sea or ocean is displaced. Tsunamis can happen most anywhere that there is an ocean or giant body of water. They especially happen where major natural events like underwater earthquakes or volcanoes can happen.

A tsunami can be generated when convergent or destructive plate boundaries abruptly move and vertically displace the overlying water. There is usually a movement underwater, like an earthquake, where the earth's plates push together, or a landslide, which causes a wave to be generated. When tectonic plates slide on each other, that's when an earthquake may happen. Because they can slide under the ocean, the impact can make the water form a giant wave. This wave is massive - nothing like what a surfer seeks. The wave can be meters high, and as it rushes closer to the coast it gains enough momentum to wreak massive damage on land. The momentum slows upon reaching land, but it is still a major force.

Get in a pool or the bath tub and put your hand a good ways down and then pull it up quickly but not out of the water, pull up strong but don't break the surface and watch the result. Not exactly a tsunami, but a simple version of the science.

Tsunamis can be caused from different kinds of events, including, but not limited to:

Sea bed earthquake, displacing water (the most likely cause).Distance landslides into the ocean or sea.Tropical storms or hurricanes.Volcanic disruption.Meteor striking the ocean or sea. More details

Most tsunamis occur when there are underwater seismic events such as an underwater earthquake or volcanic eruption. This normally occurs along plate boundaries. Subduction in convergent boundaries account for most tsunamis. This will cause shock waves to be radiated out of the epicenter. There will be a rise or fall of the seabed. This displacement will create a wave which cannot be clearly detected from shore. These waves can travel at speeds up to 700 mph (i.e. the speed of sound in water). As the wave gets nearer to the shore, the wave will compress and gain height in the shallower water. The waves can be up to 100 ft. (30 m) or more when they come ashore.

Tsunamis can also occur because of landslides. When land subsides into water bodies (usually extremely large landslides), they can create a wave that resembles a tsunami. The wave of these kinds of tsunamis will not be very high, unless a huge volume of rock or ice is involved.

Tsunamis can also occur when asteroids fall into the water bodies. This is extremely rare, and they must be extremely large to cause a large water displacement to form a wave. Meteorites will not cause high waves as they are usually much smaller than asteroids.

Some meteorological storm conditions such as deep depressions causing cyclones, hurricanes, strong winds and other similar occurrences can generate a storm surge, which can be several metres above normal tide levels. This is due to the low atmospheric pressure within the centre of the depression. As a storm surge comes ashore, it can resemble a tsunami, inundating vast areas of land.

Distances and Travel Times
Length and Distance

What is the total length of Australia's coastline?

According to the Australian Geoscience website, the length of Australia's coastline is:

Mainland = 35,877 km

Islands = 23,859 km

Total = 59,736 km

Estimates and sources vary widely (see the related link for an explanation) but the above is the Australian government's own Geoscience website, so presumably is one of the more accurate sites.

Colonial America
Lakes and Rivers

What are some of the important landforms and bodies of water in the middle colonies?

Some rivers were the Delaware River and the Hudson River, named after Henry Hudson who founded the New York colony.

One of the bodies of water is the Atlantic ocean.

Aside from the ocean the most important body of water is the Chesapeake. The Potomac, The Rappahanock, The James, The Patuxent, The Patapsco, The South, The Choptank and The York Rivers are a short list of those that were used.

The Appalachian mountains were the biggest land form that affected anyone in the colonies but only toward the latter part of the 18th century.

Mind you there are a bunch of others that no doubt affected people.

Oceans and Seas

What is the Land next to the sea called?

The border between land and sea is called the coast.

Land which is at sea level and next to the sea is called the shore.

A beach.


How many miles of coastline does Denmark have?

I'm not sure, but it's around 80-90 percent covert by costlines.


Where is the western and eastern coastal plains meet?

The pelvic bones, or "hip bones" are also called the innominates, the os coxae or the pelvis. They are among the bones that comprise the pelvic girdle.


What are the two main factors that affect how a coastline erodes?

the hardness of the rock and the energy of the waves


What is the South East Essex coastline like?

The nature of the South East Essex coastal landscape

The County of Essex is in the south-east of England and is located just to the north-east of London (Capital of England), the south-west part of the county forms the north-east edge of Greater London.

Essex has the longest coastline of any English county. A straight line drawn parallel to the coast from the Thames in the south to the Stour in the north is about 50 miles in length but follow the convolutions of the coastline and you will cover nearer 400 miles.

Lakes and Rivers

What is difference between estuary and delta?

Estuaries are flooded valleys at a river's mouth. Deltas are prograding wedges of sediment at a river's mouth.

Estuaries may develop into deltas overtime as more sediment builds up and out at the river's mouth.

Estuary is a zone of mixing of fresh & saline water.........but delta is made of fresh water's silt near a sea.....

Thunderstorms and Lightning
Earth Sciences
Oceans and Seas

How are sand-spits formed?

Spits form as a result of deposition by longshore drift, which is the movement of sand along the coast by the waves. The spit is formed when any material that is being carried by the waves gets deposited due to a loss of the waves energy, this could be because of a change of wind direction, or an estuary in the opposing direction slowing it down. As time progresses the deposited material forms a spit.


What is the length of Balochistan coast line?

It is 750 kms (466miles). Source: Balochistan Economic Report by World Bank and Asian Development Bank.


What can tsunamis cause?

Tsunamis can cause financial ruin and harm to humans: loss of livestock, loss of loved ones, home loss, job loss, loss of crops and food supplies, leakage of sewage into fresh water sources causing disease, loss of all personal belongings, business losses and other destruction from which many never recover. Other impacts of tsunamis on governments include that many citizens will be homeless, unemployed, hungry, injured, and unable to pay taxes.

Some environmental impact could be: wildfire; injured and killed people, plants and animals; deforestation; damage to coral and marine reefs; destruction of buildings and homes; ruin of businesses; damage to power plants; release of nuclear material from a nuclear power plant; and billions of dollars worth of more destruction.

If you are in the sea when one occurs, the most you will feel is a bump, like a large underwater wave. Tsunami waves can move right under large vessels on the water without notice until the wave reaches the more shallow waters near shore where they can rise as much as hundreds of feet above sea level.

Once it hits land, then the chaos occurs.

The first wave is slow moving, going crawling on the floor of the sea bed. The next wave rides on the first, moving fast and with a very large volume. These enormous waves cause death and destruction on islands or coastal areas.

It causes damage and floods.

When a tsunami wave comes ashore, it can affect a huge area of land, transforming the landscape. First, a tsunami wave throws salty seawater over the land. Too much salt is bad for living things, so if soil becomes too salty, crops cannot grow or will not grow well. In addition, the force of a tsunami can ruin pipelines and factories. This lets out sewage, oil, or dangerous chemicals into the environment. It can take many years for the environment to revert to normal.

A tsumani affects the Earth by killing or damaging everything in its destructive path. Plants and animals are hurt if they do not sense the pending tsunami and leave the area before it hits.


Tsunamis will definitely cause casualties and injuries. Tsunamis, as they originate from the sea or another large body of water, will wash fishing boats and other boats anchored close to the shore (such as cruise ships) onto shore and sometimes deep inland. The boats will be stuck on shore and usually wrecked from the forces of the event.

The tsunami will also cause fish and marine life to be washed onto shore and trapped there to die.

They can also flood the lands near the shore, causing people to die from them. They will damage the crops and cause nearby buildings to collapse. Some people might be trapped under the buildings and die. They uproot trees too, causing them to fall on houses and people.

Lastly, they cause economic decline as the people and governments have to spend a lot of money rebuilding the houses and restoring the original landscape. This can be extremely costly, especially if it is a beautiful resort area. They would also have to compensate the victims' families as a form of comforting. They would also face a decrease in tourism.

Due to the damages and loss of life, tsunamis can also cause despair problems to survivors and witnesses of the tsunami, including relatives of the victims. This problem is a most serious one, as it is very difficult to cure and it takes a very long time.


Why are coastal sand dues often fenced off?

Sand dunes protect the land from flooding and other natural disasters that are caused by the sea. They also do much more. See Related links.

Road Distance

How many miles is California's coastline?

The coastline is 840 miles. The tidal shoreline including small bays and inlets is 3427 miles.


What are the main occupations of the people living in coastal areas?

the main occupations are fishing,pearl diving,farming,resorts,boat hiring

Oceans and Seas

What ocean is on the East coast of the US?

The Atlantic.

Countries, States, and Cities

Which countries are frequently occurred by tsunami?

New Zealand


Southern part of Eastern Coastal Plain is known as?

coramandal coast


What is hard coastline?

a rocky shore


Which country has the longest coastline along the shores of the Red Sea?

Saudi Arabia


How long is the Alaska coast line?

The Alaska coastline is roughly 34,000 miles long.

South America

What are the major geological features of South America?

The Andes mountains, the Amazon basin, and the Nazca Plains. The Nazca plate is currently being subducted under the South American plate. The Amazon basin encompasses the largest drainage area in the world and the Amazon river is number one in terms of water discharge. The Brazilian Shield and the Guiana Shield are located in north western South America. They are both Precambrian.

Charles Darwin
Erosion and Weathering

How geology affects a coastline?

A coastline may exist on a plate boundary and be subject to uplift and/or volcanism by plate tectonics. Coastlines are also areas where calcareous animals such as coral live and build huge reefs which are considered fossiliferous stone. Coastlines at estuaries are great repositories for eroded rock entering through rivers which drain mountain ranges and land masses. Through water movement, larger land rocks are eventually pulverized into solution. Geology will determine the appearance of the coastine, whether it's rocky, sandy, or gently sloping. The color of the sand will be determined by what rocks are eroding near the coast. And finally, the effects of erosion can cause a coastline to recede and eventually disappear or through volcanism, to appear and expand, both being the case with the Hawaiian Islands.


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