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See also Physical Features for specific examples of many definitions given here

After Shock
An aftershock is an earthquake that occurs after a previous earthquake, the main shock. An aftershock is in the same region of the main shock but always of a smaller magnitude. If an aftershock is larger than the main shock, the aftershock is re-designated as the main shock and the original main shock is re-designated as a foreshock. Aftershocks are formed as the crust around the displaced fault plane adjusts to the effects of the main shock. They may be one or two or many, during a few hours or even for a couple of days.

Avalanche, called also as snow slide or snow slip, is a rapid flow of snow down a slope. After initiation, avalanches usually accelerate rapidly and grow in mass and volume as they entrain more snow. If the avalanche moves fast enough, some of the snow may mix with the air forming a powder snow avalanche, which is a type of gravity current.

Bay   see also   Gulf
Bay is a body of water forming an indentation of the shoreline, larger than a cove but smaller than a gulf - such as Bay of Bengal on the Eastern side of India.

Bearing is the coordinates of the earth by which a location can be located, such as 57 degree East and 40 degree South. In Bearing both the values are necessary to locate a place, so to know about a position.

A canal is a man-made stream taken out the water from a river for some specific purpose, such as to irrigate the fields, or to take some of its water to some other location. These canals can be big or small. A big canal later can be used to have water from it through small canals to the farms or villages. Suez Canal joins two seas - Red Sea to Mediterranean Sea

Cape is the last point of any land mass, normally a peninsula, which normally penetrates into the sea conically.

Creek is a long waterway coming from the sea through the land inside mostly for a short distance, but it might be long also.

Degrees, Minutes and Seconds    see also   Earth-3
As Earth is round, and a circle is also round, the Earth has been imaginarily divided into 360 degrees for the convenience of finding a location. These lines go from North to South and are called Longitude. As a location needs two coordinates for its identification, to its aid are Latitude which run from West to East across the globe.

Delta is a place where a river falls in the sea or ocean or a large body of water. There, normally, it flows out in several streams and empties itself into the sea. All rivers have their delta. Some deltas are big while some are small. Their size depends on the size and volume of the water in the river and the slope of the land towards the sea.

Desert   see also   Sand Dune
Normally a desert is a part of the terrestrial surface of the globe which is covered only by sand for many miles. A part of land can also classified as a desert where little rain falls, or in which few plants or animals are able to exist. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation.
It is not easy to cross desert, as there is no water around, and it is very hot because of sand. Besides there are no landmarks and no roads. People can mistakenly take the large heaps of sand (they are called sand dunes - see below) around in desert as the landmarks, but as very fast and strong winds blow there, they move those large heaps from one place to another within hours depending on the direction of the wind. So if a person has seen a sand dune at one place in the morning, coming back from the same way he may not find that dune at the same location. Here days are very hot and nights are very cold.

About one third of the land surface of the world is arid, semi-arid or located in the polar regions, which also have little precipitation and are sometimes called "cold deserts". There are a number of ways of classifying deserts including by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical locations.

When people have to go in desert, they go on camels as camel is the only animal which can hold water for several days. It has a pouch in its throat where it stores water. Besides it has cushion in his paws to tolerate the heat of the sand throughout the day. That is why it is called the "ship of the desert".
See some of the pictures of Desert Vegetation and Animals here

A flood is an overflow of any amount of water that reaches land. Floods occur usually when the volume of water within a body of water, such as a river or lake, exceeds the total capacity of the formation, and as a result some of the water flows or sits outside of the normal perimeter of the body of water. However, floods may be caused by heavy rains, or dams are damaged by sudden overflow of water or by earthquakes, etc

Foreshock    see    Aftershock

The English word geyser (a spouting hot spring) derives from Geysir. Eruptions at Geysir can hurl boiling water up to 70 meters in the air. However, eruptions may be infrequent, and have in the past stopped altogether for years at a time. The Great Geyser, is a geyser in southwestern Iceland. It was the first geyser described in a printed source and the first known to modern Europeans. 

Gulf   see also    Bay
Gulf is a large water body going into the land area. Gulf is bigger than the bay - Arabian Gulf. Or A large area of a sea or ocean partially enclosed by land, especially a long landlocked portion of sea opening through a strait.
See the List of Gulfs here.

Hill   see   Mountain

Iceberg   see also   Ice
Iceberg is a large piece of freshwater ice that is broken off a glacier (again very large ice sheets in mountains) or an ice shelf and is floating freely in open water. It may subsequently become frozen into pack ice (one form of sea ice). As it drifts into shallower waters, it may come into contact with the seabed too. The problem with an iceberg is that it is seen only as a tip on the water. Its only 10% part is visible over the water and the rest 90% is inside the water. Ships must be very careful of them, because one can never guess the shape and size of iceberg under water.

An area of shallow water separated from the sea by low sandy dunes.

Lakes are the natural body of water. A lake can be of any size, small or big and shape, round or long. It can be as small as having a few yards, 40-50-70 yards, diameter; as big as USA's five Great Lakes, which theoretically should be counted as seas. They are made by volcanoes also and many lakes are man-made too now a days, such as in the US, all Ohio lakes are man-made.

Landslide is when a large piece of land, usually from a hill or a mountain falls after breaking of the main place.

Latitude   see also   Earth-3
Latitude is an angular distance from the Equator. It is the imaginary lines dividing the Earth going from West to East. The main such lines are (1) Equator which divides the Earth in half or passes through the center of the Earth.
(2) There are two more lines which are on equal distance from Equator - at 23.5 degree - one in North another in South. The Northern line is called The Line of Cancer and the Southern one is called Line of Capricorn. Their specialty is that the Sun goes only up to these lines - in North up to 23.5 Degree and in South too up to 23.5 degree. It does not go beyond these points. For the same reason there is 6 months day and 6 months night in Northernmost and Southernmost regions. The movement of the Sun in this way decides the seasons and the length of day and night. Near the Equator, normally the length of day and night are almost equal, while in northernmost and southernmost areas have 6 months day and 6 months night, of course in opposite months of the year.

Line of Cancer and Line of Capricorn   see also   Earth-3

Location is the place where a city or a mountain or anything is located in the world. Normally the Location is indicated by Longitude and Latitude - as you plot a dot or line on a graph. Location is of two types - Absolute and Relative. Absolute Location is indicated by the Longitude and Latitude, such as 40 W 30 S Relative location is indicated by the direction and distance from a certain place or landmark to another place. For example, US office is on Galveston Island, located in Southeastern Texas in the Gulf of Mexico, about 48 miles Southeast of Houston - that is called relative location.

Longitude   see also   Earth-3
Longitudes are the imaginary lines dividing the Earth in 360 degrees. Longitude decides the time. At each 1 degree there is a difference of 4 minutes - 1440 / 360 = 4. As a circle the Earth is divided into 360 degrees and since the Sun revolves around it in 24 hours, there is a time change of 4 minutes at every degree. For example if there is 5.00 PM at 57 degree, at the same time there will be 5.12 PM at 54 degree and 4.48 PM at 60 degree. This measurement, along with the measurement of Latitude, is used to locate a location on the map of the Earth

Meridians   see   Longitude


Meet me for lunch at 23 degrees, 4 minutes North and 45 degrees, 15 minutes East.
After a confused silence a voice volunteered, "I guess you'd be eating alone."
Why because at that location there was no house and no restaurant.

Moon   see also   Moon
Moon is a round object that circles a planet. Almost all planets have moons. Earth is a planet and Earth has a Moon. There are a total of 166 moons in our solar system. A planet can have more than one moon too. For example,
Earth has 1 moon
Mars has 2 moons - Phobos and Deimos
Mercury - no moon
Venus - no moon
Jupiter has 67 confirmed moons - Europa and Io.
Saturn has 62 moons - 53 of which have names, 13 of which have the diameter of 50 kms, otherwise its moons are numerous

Mountain is that part of the earth which has risen quite high from its level. This height can go up to any height. The low height mass is called hill and a very high mass is called mountain. There is no clear cut difference between them but just a sight. Himaalaya is the highest mountain on the Earth.

Mouth is the place where a river falls in the sea or ocean. It is after Delta.

Its plural is oases. Oasis is a place
 in deserts where one can find some water and date palm trees. Normally it is very difficult to find water in deserts.

Parallel Lines   see   Latitude

Pass is a walkable pathway between the mountains. It is different from the valley that a valley may be narrow or wide, with villages or cities or just empty places. Although many people live around the pass too. It is in fact a narrow route across a relatively low notch or depression in a mountain barrier, a road, channel, or other way providing a means of passage, as through an obstructed region or other barrier.

Sometimes a navigable channel, as at the mouth or in the delta of a river is also called pass.

Khyber Pass, one of the oldest passes in the world, is the pathway connecting Pakistan with Afghanistan cutting through the North-eastern part of the Spin Ghar mountains. Throughout the history it has been an important trade route between Central Asia and South Asia and a strategic military location. The summit of the pass is 3.1 miles inside Pakistan at Landi Kotal. It is at the 3,500 feet height.

Peninsula is that part of land which goes far into the sea conically, such as Indian Peninsula, Kamchatka peninsula on the eastern coast of Russia in the North.

A planet is a large round object which goes round a star, for example our Earth is a planet, because it goes round a star "the Sun". In the same way our Sun has some other planets also, such as Mars, Mercury, Jupiter, Venus, Saturn, because they also go around the Sun like our Earth.

Plateau is a very high flat place on the mountains, such as the Plateau of Pamir in Tibet.

River is a natural body of water which comes out from a lake or mountain and flows downward in the plains taking its own natural course towards a sea or ocean. River Nile of Egypt is the longest River on the Earth.

Sand Dune   see also   Desert
Sand dune is a heap of sand (or a small hill of sand) which is normally found in sandy deserts where you can see the Earth as a plate - as you see it while you are in seas or oceans. It can be small or large, so small that it looks like a ridge, and so large that it might be 20-30 feet high and 20-30 feet wide. They are made by wind or water.

One meaning of source is the place from where a river starts, for example the source of Blue Nile is Lake Tana, the source of River Ganges is supposed to be the Gangotri Mountain in Himaalaya.

A star is an object in space that is made of burning gas and that look like points of light in the night sky. With this definition our Sun is a star. It has its planets and its planets have their moons.

A strait is a naturally formed, narrow, navigable waterway which connects two navigable water bodies  It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not navigable, for example because it is too shallow, or because it contains an un-navigable reef or archipelago. When it is man made it is called canal, such as Suez Canal (joins Red Sea and Mediterranean Sea) or Panama Canal (joins Atlantic Ocean to Pacific Ocean).

Some straits are Cook Strait in New Zealand, Strait of Gibraltar (connects the Mediterranean Sea to Atlantic Ocean - Spain is on its left and Morocco is on its right).
English Channel - The English Channel, often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates Southern England from Northern France, and joins the North Sea to the Atlantic Ocean. It is about 350 Miles long and varies in width from 150 Miles at its widest to 20.6 Miles in the Strait of Dover.
See the list of Straits Here.

At time to time water level of sea rises up and then falls down. This activity of the sea is called tide. When the water rises up it is called High Tide and when the water level falls down it is called Low Tide. Normally on the day of Full Moon sea water rises with the gravitation power of the Moon, so on that day there is High Tide. After that it starts receding.

Time Zone
At every 1 Degree Longitude, 4 Minutes time decreases towards the West. Some countries are small, some are very large like USA, Canada and USSR which are spread for several Degrees. These large countries divide their country in several Time Zones to depict near correct time to that area, and thus maintain several Time Zones. For example, the USA maintains 6 Time Zones. Their names and their respective time are given here  -
(1) Eastern Time Zone - -5 hours to Meridian -  if 12.00 PM is in London, the Eastern Time Zone will have the time 7.00 AM,
(2) Central Time Zone - -6 hours to Meridian -  if 12.00 PM is in London, the central Time Zone will have the time 6.00 AM,
(3) Mountain Time Zone - -7 hours to Meridian -  if 12.00 PM is in London, the Mountain Time Zone will have the time 5.00 AM,
(4) California Time Zone - -8 hours to Meridian -  if 12.00 PM is in London, the California Time Zone will have the time 4.00 AM,
(5) Alaska Time Zone - -9 hours to Meridian -  if 12.00 PM is in London, the Alaska Time Zone will have the time 3.00 AM,
(6) Hawaii Time Zone - -10 hours to Meridian -  if 12.00 PM is in London, the Hawaii Time Zone will have the time 2.00 AM,

All time should be calculated in this way.

Valley is a low flat or no flat place between two hills or mountains. Or valley is the low flat place which is surrounded by hills or mountains. They are naturally made. Most of the times, these valleys are inhabited,

A volcano is an opening or rupture in the crust of the Earth or the planetary mass object which allows the hot lava, volcano ash and gases to escape from below the surface. On Earth volcanoes are generally found where tectonic plates are diverging or converging. Erupting volcanoes can pose many hazards. Volcanic ash can be a threat to aircraft, especially with jet engines where these particles are melted by a high operating temperature. Large eruptions can affect the temperature as the ash can cover the Sun. Historically volcanic winters have produced catastrophic famines. The most common look of a volcano is conical mountain throwing lava and poisonous gases from a crater at its summit. Hawaii and Indonesia, are the biggest places for volcanoes.

Well is a man-made source of water which is dug through the land to get water. Normally the water table under the earth decides the depth of the well. At the same time if the water table is too deep, the well is not economical to dig. Till the water table is there, the well will run, as the water table will recede or be dry, the well will also be dry. The water is drawn by a rope and a bucket. These wells are good for houses.

Sometimes Tube Well are also dug. In this type of wells water is drawn by machines run by electricity and can be controlled by them too. These are good for farming purposes and are found at farms. When the farmer wants he can open the tube well and water his farms for 1 hour or 2 hours, and then stops it.



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Created by Sushma Gupta on January 15, 2002
Modified on 01/27/14