Category: Geography Notes PPT

The concept of sedimentary facies depicts that the sedimentary facies are actually the bodies of sediment recognizably distinct from adjacent sediment accumulated in a different depositional environment. As conditions alter with time, so various depositional sites may also their shapes and characteristics.

Usually, facies are differentiated by the aspect of the rock or sediment that is being studied. Therefore, facies based on petrological characters such as mineralogy and grain size are referred to as lithofacies, whereas facies based on fossil content are known as biofacies.

Types of Sedimentary Facies

Sedimentary facies indicate a depositional environment, each facies being a distinct type of sediment for that area or environment. Thus, there are various ways of describing or designating sedimentary facies. Taking into account the principal physical (or lithological) characteristics, one is able to identify lithofacies. The biological (or more appropriately, paleontological) characteristics—the fossils—describe biofacies. It is quite usual to speak of alluvial facies, bar facies, or reef facies, considering the environment as a criterion.

Facies under coal, clay, shale, and sandstone may be repeated several times and are known as cyclothems. Rhythmic or cyclic sedimentation has been documented in various rocks in different parts of the world and may occur in various ways; however, re-assessment of many successions originally defined as cyclic displays that this phenomenon is not as common or as consistent as had been thought of.

Sedimentary Facies Analysis

Talking about the Sedimentary facies and reservoir characteristics and analysis, we will undertake the 8 sandstones. This sandstone is a unit in the Western Sulige field which is one of the most prolific gas‐generating intervals in the Ordos Basin.

Purpose of Sedimentary Facies Analysis

Sedimentology and reservoir characteristics analysis are basically undertaken in order to interrogate the reservoir’s petrological, petrophysical, diagenetic properties, and production features. Three types of sandstone and four types of lithofacies were identified. The two frequently seen lithofacies are labelled lithofacies C and D.

Lithofacies C is made up of fine‐ to medium‐grained litharenite (Sandstone I); lithofacies D composed of coarse‐grained sublitharenite (Sandstone II) and coarse‐grained/gravelly litharenite (Sandstone III).

Results of Sedimentary Facies Analysis

In comparison, Lithofacies C, Lithofacies D was accumulated as a series of overlaying sand sheets in a greater energy fluvial system. The firmness of Sandstone I is an outcome of an event of intense compaction of the rock substructure giving rise to early dissolution of grains and deformation of ductile rock splinters. The mechanisms that resulted in the low permeability of Sandstone II and Sandstone III are more complicated. Moreover, intense compaction, the development and emplacement of quartz and clay cements plays a critical factor. Besides these,

• Evolution of Diagenesis and porosity assessment exhibits that the petrophysical properties of these sandstones were better at the gas charging time.

• The permeability and porosity values of Sandstones II and III are same at the surface, but considerably different at formation pressure. This causes differences in gas production rates.

• Sandstone II possesses greater gas production rates and cumulative gas production than Sandstone III.

• The presence or absence of Sandstone II monitors and curbs the dispersion of sweet spots within less productive tight gas reservoirs.

Fun Facts

• The suite of structures actually develops facies.

• Sedimentary facies are either terrigenous, emancipating from the deposits of particles weathered from older rocks and carried to the depositional site; biogenic, depicting depositions of whole or broken shells and other hard parts of organisms; or chemical, depicting inorganic precipitation of substance from a solution.

• Each facies consists of a three-dimensional configuration and overtime shifts its position.

• A facies (Latin terms used for appearance or aspect) is a body of rock (i.e. a series of beds) or sediment marked by a specific combination of compositional, biological and physical structures that differentiate it from bodies of rock/sediment.

• A sedimentary facies contains a set of properties that makes it distinctive, which the geologist defines.

• In general, facies are described based on a suite of characteristics in rocks/sediment.

India is the ancient civilization in the world. It has displayed remarkable progress in many fields such as agriculture, technology, economic development, and industry and has contributed forward in the making of world history. 

India is located in the Northern hemisphere. By land area, it is the seventh-largest country and the most populous democracy in the world. Bounded by the Indian Ocean, The Arabian Sea, and the Bay Of Bengal. It shares its land borders with Pakistan, China, Nepal, Bhutan, Bangladesh, and Myanmar. The following points will discuss more about its location:

1. The land extends between latitude 8°4’N and 37°6’N and longitudes 68°7’E and 97°25’E.

2. The Tropic Of Cancer divides India into two equal parts.

Size of India

It is the seventh-largest country in the world covering a total area of 3,287,263 square kilometres. It has a land frontier of 15200 km and a coastline that covers 7516.6 km. The following points discuss more about the landmark.

1. India is covered by mountains in the northwest, north, and northeast.

2. The landmark begins to taper and extends towards the Indian Ocean, dividing into two seas. The Arabian Sea on the west and the Bay Of Bengal on the east.

3. Time along the Standard Meridian of India is taken as the standard time zone of India. 

4. The Standard Meridian passes through Mirzapur in Uttar Pradesh (82°30’E)

India and the World

The Indian landmark is centrally located between west and east Asia. The countries in the west and east are connected through trans-Indian routes. India enjoys its contacts with the world via land routes more than maritime contacts and is the only nation that has an ocean named after it ( Indian Ocean )

India has contributed a lot to the world in the forms of philosophies and mathematics. Philosophies include Upanishads, Panchtantra, and Ramayana Mahabharat. Mathematics contributions include Indian numerals and decimal systems.

Due to various contributions to the outside territory, India’s architecture was influenced by Greek sculpture and architectural styles of West India.

India’s Neighbours

India occupies an important position in South Asia and has 29 States and 7 Union Territories. Its boundaries are shared with Pakistan, Afghanistan, Bhutan, Myanmar, Bangladesh, and China. The southern neighbours across the sea consist of two island countries, namely the Maldives and Sri Lanka. 

Sri Lanka and India are separated by Pak Strait, a narrow strip of sea. India stands apart from the rest of Asia and always has had strong geographical and historical links with its neighbours.

Climate 

India hosts 6 major climatic conditions ranging from the arid desert, glaciers, humid tropicals, and alpine tundra. The Himalayas act as a barrier from Central Asia. Due to this northern India is kept warm or mildly cool during winters. In summers, it is relatively hot. The Tropic Of Cancer – the boundary between tropics and subtropics passes through the middle of India and the whole country is considered to be tropical. It governs a tropical rainy climate in some regions with persistent warm or high temperatures. Also here a tropical wet and dry climate is more common.

Summers last between March and June. The rain-bearing monsoon clouds are attracted to the low-pressure system. The southwest monsoon diverges into two parts, the Bay Of Bengal and the Arabian Sea. Winters in the peninsula experience mild to warm days and cool nights. Temperatures in some parts fall below freezing. Most of the northern part of India is plagued by fog during the season. The highest temperature being recorded in India is 51 degrees in Phalodi ( Rajasthan ) Celcius and the lowest temperature being recorded is -60 degrees Celcius in Dras ( Jammu and Kashmir )

Earth as we know Is the 3rd planet in the solar system. The solar system is a system of planets wherein all the planets, 8 to be precise revolve around the giant ball of fire, the sun. All these 8 planets revolve around the sun in an orderly manner and always follow the same trajectory. The trajectory or path followed by every planet is known as its orbit. Every planet has a different orbit. These orbits aren’t circular in shape, in fact, they are elliptical. The radius of orbits varies and the increase in the radius results in the arrangement of the planets in an orderly manner. 

What are the Two Motions of the Earth? 

As we just learned, every planet revolves around the sun in a specific orbit. So does our planet. Our planet revolves around the sun with a period of 365.25 days. Likewise, every other planet has a time period of its own, this time period increases as the distance from the sun increases. Revolution, however, is just one of the motions executed by our planet, earth. Our planet also rotates on its own imaginary axis. Both of these motions happen together, the earth revolves and rotates simultaneously. 

Rotation of the Earth

The earth rotates about its tilted imaginary axis from West to east. The time period for this rotation is 24 hours. That means the earth completes one full rotation after every 24 hours. So your net displacement after 24 hours will be 0. If viewed from the pole star, the earth appears to rotate counterclockwise. 

Some History About the Discovery of Rotation of Earth

Some of the scholars in 470 BC believed that the rotation of the earth is just an apparent thing and in reality is just an illusion. However, it was for the first time in 499 BC, Aryabhatta, an Indian scientist stated that the earth rotates about a fixed axis daily. Soon the statement spread to the west and western philosophers started believing that the earth does rotate about a fixed axis. 

Revolution of Earth Around the Sun 

Revolution is the second phenomenon executed by the earth. The earth goes around the sun in an elliptical orbit every 365.25 days, this periodic motion of the earth is called a revolution. The earth’s orbit is an eclipse and the earth-sun barycenter is one of the focuses of this ellipse. The eccentricity of the ellipse is 0.0167. Ever wondered why the earth revolves around the sun? Well, if not then let’s find the answer out today! 

Why Does the Earth Revolve Around the Sun? 

Why does the earth have to revolve around the sun? Well, this is because the sun has a huge mass. It’s a lot greater than the mass of earth or any other planet in the solar system. Sun is the biggest body in our solar system and hence it has the highest gravitational force. Gravitational force is the force between two bodies that is dependent on the masses of both bodies. The higher is the mass, the stronger is the gravitational pull. Hence, the sun being the heaviest controls the motion of all the other planets in the solar system. 

Some Numbers That Will Take You By Surprise! 

The History Behind the Discovery of Revolution

Heliocentrism is the first-ever model which was designed according to the theory which said that the sun is at the center of the solar system. Until then, the theory of geocentrism was believed according to which the earth was the center of the solar system. Soon Copernicus came up with his theory of a static center, that is the sun. And all the planets moved around this static center In fixed orbits. Then, experiments were conducted to prove the theory and soon the world started believing the theory of heliocentrism. 

Fun Fact: 

The earth’s rotation period is reducing with each passing day. This means that days in the past were longer than days today. Well, this isn’t just a joke and has scientific backing to it. The earth’s rotation period is known to be decreasing as we progress forward in time. This is due to the moon’s tidal effect. According to some experiments conducted by a few learned scientists, a day today is almost 1.7 milliseconds lesser than a day, one century ago. Although, the time lag is not much, with time this shall definitely increase. 

You must have noticed or seen some lakes in the mountains which have been formed because of the melting of the glaciers. Lakes are generally found in any type of environment and all parts of the world. Here, in this article, we will be talking about a type of lake that is considered a small mountain lake or tarn. It is also known as Corrie loch. This article will help you to understand one of the types of lakes or one of the important geographical features. It will be helpful in Geography, Earth Sciences, Geology, Geomorphology and Physical Geography.

Introduction

A body of water that is surrounded by land is called a lake. It is not a part of the ocean. Most of the lakes are browsed and drained by the rivers and streams. There are many lakes which are found in the world. They are found on every continent and in every type of environment. They are generally found in mountains, deserts, on plains, and near seashores. The still bodies of water are lake as compared to the river where the water flows. Lakes are generally deeper than ponds and have a large surface area. They can contain salt and freshwater. They are larger than the ponds. 

There are different kinds of lakes found in the world. It is classified on the basis of its origin and mode of formation. The different kinds of lakes are organic lakes, volcanic lakes, glacial lakes, Tectonic lakes, fluvial lakes, Landslide lakes, Solution Lakes, Aeolian lakes, Shoreline lakes, Anthropogenic lakes, Meteorite lakes. Out of these, we came to know about the ” Tarn” which is a type of glacial lake.

Formation of Lake

The lakes are formed by erosion. When the glaciers melted, water-filled the hollows, which formed the lake. Glaciers carved deep valleys and deposited high amounts of earth, pebbles and boulders as they melted. These materials sometimes formed dams that have water and formed more lakes.

Tarn Meaning

Tarn means a small mountain lake in a hollow area surrounded by steep slopes formed by a glacier. The word tarn comes from the old Norse tjorn which means “small mountain lake with no tributaries.” It is a proglacial mountain lake which is formed in a cirque excavated by a glacier. It is found in corries which are the result of erosion of glaciers. After the glaciers have melted, it leaves behind circular hollows in the heads of the valleys up in the mountains. Such hollows are arm chaired shaped cirques and corries. The water collects on the floor of the cirques to form the tarn lakes. Both corries and tarns are typically located in higher topographies to match their glacial origins.

Definition

The word tarn is derived from the old Norse word tjorn which means a small mountain lake with no tributaries. Tarn is a small mountain lake which is set in a glaciated steep-walled amphitheatre known as a cirque. A cirque is formed by ice and indicates the head of a glacier. Some of the cirques are so furbished that a lake formed in the base of the cirque after the ice has melted. These are called tarn.

• “It is a small steep-banked mountain lake or pool.” – Merriam-Webster

• “It is a small mountain lake in a hollow area surrounded by steep slopes formed by a glacier.” – Cambridge dictionary.

• “A tarn is a small lake in an area of mountains.” – Collins dictionary.

Features

There are some features of the tarn

• Tarn is lakes that are formed in glacially carved cirques.

• They are obstructed by moraines below a tarn.

• Tarns are often full of tiny, glacially-ground sediment that pass the light and make the watercolour.

• They are found in mountainous areas.

• The highest tarns of the world are found in Snowdonia, Lake District and Scotland.

Examples 

Some of the famous examples of tarn are mentioned below:

• Lake Tear of the Clouds, Adirondack Mountains, New York.

• Veľké Hincovo, a tarn in Slovakia 

• Lousy Lake (tarn) in North Cascades National Park, Washington, USA

• Lakes of the Clouds, below Mount Washington in the White Mountains

• Banderishka Chukar seen from the Banderishka Lakes (tarns), Pirin Mountain, Bulgaria

• Gergiysko lake (tarn), Pirin Mountain, Bulgaria

• The Dreadful Lake (tarn), Rila Mountain, Bulgaria

• The Seven Rila Lakes (tarns), Rila Mountain, Bulgaria

• Marichini lakes (tarns), Rila Mountain, Bulgaria

• Sea Lion Tarn on Livingston Island in Antarctica

Conclusion

To conclude, we can say that tarn is nothing but a type of small mountain lake which is surrounded by steep slopes that are formed by a glacier. The word tarn comes from the old Norse tjorn which means “small mountain lake with no tributaries.” It is a proglacial mountain which is formed in a circle and excavated by glaciers. A bowl-shaped feature in the centre of the glacier is called cirque which is formed by ice and indicates the head of the mountains. Here, we have learned tarn meaning, definition, basics of lakes or formation of lakes, famous examples of the tarn, etc. All these things will help you to learn one of the important geographical features of the Earth. 

Whenever you search about something, let’s say about the forest or any mountain on the search engines, you will also find some related maps there. These maps will show the location and will also explain the detailed features of that forest or mountain region. You’ll be able to find accurate information such as the height of the mountains, various routes around there, the boundary of the forest and any particular species found there, etc. These maps fulfill all your requirements. These detailed maps of the geographic features are known as topographic maps. Here, in this article, we will be talking about these maps only. We will learn what is a topographic map or whole topographic map definition structure examples and other related concepts which will help you to understand this topic. Understanding this topic is very necessary because it helps in actual life for various purposes. 

Just like we study about natural habitat and clouds and other scientific things, in the similar manner we study about the surface of the land. It can contain various things such a s mountains, valleys, rivers and other things that exist on this very planet on land. Now this whole study has detailed characteristics and almost nine out of ten topographic maps show contour lines which can be called as lines of equal elevation. Now if we deeply go to understand topographic maps it can be defined as a two-dimensional representation of a portion of any three-dimensional surface on earth or of the earth. Topography can be in the shape of the land surface and the map that we usually see to understand the given area represents the land surface so basically the topographic map explains or represents the land surface. These can be called as tools used in geologic studies because they help us to configure the earth surface and read them and their characteristics properly. Just like we have sociologist, biologists to study and understand their respective subjects we have cartographers who solve the problem of representing the 3-D land surface by copying it on a flat piece of paper through the usage of contour lines which also has horizontal distances and vertical elevations which can be measured from a topographic map.

Before we go into details about a topographic map we need to understand the basic terms or the general information regarding the maps. There are various things such as map scale, vertical scale, and contour lines which will further help us understand the whole structure around topography and topographic maps.

Now maps come in a variety of skills so when we talk about map scale it can cover areas ranging from the entire earth to a Block of city or maybe less.

Maps are different but all maps do have a horizontal scale but along with the horizontal scale topographic maps also have a vertical scale to allow the determination of a point in three-dimensional space.

Contour lines pose a very important term when defining topographic maps contour lines are basically used to determine elevations and can be evaluated as lines on a map that are produced from connecting points of equal elevation. These lines are marked with their elevations and a general target so that it can represent its characteristic features evidently. In contrast lighter contour lines do not have such elevations but they can be determined by counting up or down from the nearest index contour line and by multiplying the contour interval. Contour lines can be traced in any topographic map located below the scale and so does the contour interval.

Now we already know that topographic maps represent a view of the landscape as we see it from above, so in order to perform or produce a detailed study of the landscape it is very important to construct a topographic profile or a cross-sectional design through a particular interval. A topographic profile can be defined as a cross-sectional view of a long line drawn through a portion of a topographic map. A profile may be constructed quickly and accurately across any given state line but in order to do so we need to follow a procedure.

Stream Gradient: The gradient of a stream or river is determined by measuring a section of a stream or river and dividing the distance (in miles) into the vertical difference (in feet) between the two points.

 

Topographic Map – Introduction

What is the meaning of topography? Basically, it is a study of all the geographical features that present on the surface of the Earth. These can be natural or artificial features of a particular place. Usually, these features are displayed through maps. When these features are given a graphical representation and explained through maps, they are simply called topographic maps.

 

Topographic Map Meaning

These are those maps that provide detailed, comprehensive, and accurate information of the graphical representation of any natural or artificial geographical feature that occurs on the surface of the Earth. 

Contour lines are used in topographic maps for providing detailed information. These are the lines that are made by connecting the same points of equal elevation. Not all contour lines are displayed in topographic maps but samples of them are used. These kinds of maps are generally created by the government agencies for the administration of the country.

 

Topographic Map Definition

• As per Oxford reference, “Topographic Map is a map which indicates, to scale, the natural features of the Earth’s surface, as well as human features, with features at the correct relationship to each other.”

• According to the dictionary, “Topographic Map is a map showing topographic features, usually using contour lines.”

Vegetation, Elevation and Glaciers

The variation of the leaves or contours of a reason are often shown as brown lines that connect points of equal elevation on a map. With these lines we can easily measure and show mountain heights, steep slopes and ocean depths in a flat map. Topographic maps and the studies conducted may also include vegetation such as forests at each level of a mountain. Different forests such as large and sparse vegetation can be represented by dark shades of green and light green accordingly. Similarly larger and deeper bodies of water are outlined in darker shades of blue and the lighter shades of blue indicate smaller lakes and ponds. For glaciers and snow fields which are snow covered almost all year round can be outlined in white called as wide areas along the same contour lines.

Uses of Topographic Map 

It can have several uses which are mentioned below:

• These maps can be used for any kind of geographic planning or architecture purposes.

• It can be used in matters of Earth Science and Geography.

• It can be used in mining and other such purposes like the construction of ponds etc.

• It can be used for recreational purposes as well. For example, hiking or mountaineering, etc.

• It can be used to get any detailed description of any area or any geographical feature. For example, drainage, landforms, forests, communication or transportation routes, etc. 

• It can be used to get detailed information on any man-made features as well.

• It can be used in civil engineering as well.

• It can be used by the government for planning or administrative purposes or can be used by the private Industrial players as well.

 

Structure

These maps have a very comprehensive and detailed structure of any feature that occurs on the surface of the Earth and this structure provides all the information about that particular feature with the help of contour lines and graphical representation. This structure can include the following aspects in the maps:

 

Topographic Map Example

These maps can be of any country or any specific region or any topographic feature. Maps based on specific themes are called thematic maps. Some examples of topo maps of different countries and others are given below:

Topographic Map – Germany

 

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Topographic Map – Russia

 

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Topographic Map – Spain

 

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Topographic Map – India

 

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Topographic Map – Highways ( India )( Thematic Map )

 

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Topographic Map – Forest ( Thematic map )

 

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Did You Know?

If you know how to use a compass and a topographic map of any place which is unknown to you, you can be a good explorer even without a GPS. 

 

Conclusion

Thus, we know that maps play an important role because they can represent such a large-scale thing into a very small scale of paper. They help us to organize information about any region or place of any feature. Topographic maps will enlighten you about different features and their elevation levels. Here, in this article, we have covered topo maps. We have learned about topography definition geography, topographic map definition structure examples and other related concepts in this article. This will help you to understand the importance of topo maps and will also help in studying Geography and Earth Science. 

In physical geography, tundra can be defined as a kind of biome in which cooler temperatures and short growing seasons lead to hindrance in the growth of trees.

Dwarf shrubs, mosses, sedges and grasses, and lichens are composed of tundra vegetation. In some regions of tundra, the growth of scattered trees is observed. The ecotone (or ecological boundary region) is referred to as the timberline or tree line and is present in between the tundra and the forest. Further, the tundra soil is found to be highly rich in phosphorus and nitrogen. There exist three regions and associated kinds of tundra, namely, Arctic tundra, alpine tundra, and Antarctic tundra.

Arctic Tundra

The Arctic tundra is found in the Arctic regions of the northern hemisphere, located north to the subarctic boreal forest. The term “tundra” commonly applies to the regions whereby permanently frozen soil or permafrost is the subsoil. (In general, it can also apply to the barren plain, wherein it might include northern Sapmi.) Permafrost tundra covers large areas of Canada and northern Russia. Many groups are mainly nomadic reindeer herders throughout the polar tundra, including the Nganasan and Nenets in the permafrost zone.

There are regions of solid landscape in the Arctic tundra where it is frozen for most of the year. From 25 to 90 cm (10 to 35 in) down there, the soil is frozen, making it difficult for trees to grow. Rather, only certain forms of Arctic vegetation, low-growing plants including the heath (varieties of Ericaceae including certain crowberry and black bearberry), moss, and lichen, can withstand bare and often rocky ground.

In the polar tundra zones, there have been two primary seasons, summer and winter. It is quite cold and dark throughout the winter, with a mean temperature at about -28° C (-18° F), often dipping as low as -50° C (-58° F). Severe winter temperatures on the tundra, however, do not fall as deep as those encountered further south in the taiga areas.

Temperature goes up somewhat during summers, and the upper layers of seasonally-frozen soil disappear due to melting. This leaves the earth very moist and soggy. During the warmer seasons, the tundra is covered in marshes, wetlands, bogs and streams. During the season of summers, daytime temperatures usually rise to approximately 12° C (54° F), but may sometimes drop to 3° C (37° F) or maybe even below zero.

Antarctic Tundra

Antarctic tundra is found to happen on the Antarctic as well as in the subantarctic islands. These islands may include South Georgia and the Kerguelen Islands and the South Sandwich Islands. Much of Antarctica is highly cold yet dry for supporting the vegetation. Moreover, the polar tundra covers much of the continent there.

Some parts of the globe, however, specifically the Antarctic Peninsula, carries the areas of rocky soil which is highly preferable and supportive for the life of plants. Actually, the flora comprises almost 25 liverworts, 100 mosses, 300-400 lichens, and approximately 700 species of aquatic and terrestrial algae that live in uncovered rock and soil regions along the continent’s coast.

In the western and northern parts of the Antarctic Peninsula, Antarctica carries two different kinds of flowering plant plants, namely, the Antarctic pearl (Colobanthus quitensis) and the Antarctic hair grass (Deschampsia antarctica). The Antarctic tundra, in comparison to the Arctic tundra, lacks a large mammal fauna. And this is mainly because of the physical isolation from the other major continents.

Alpine Tundra

Since the weather and soils at higher elevations obstruct tree growth, alpine tundra does not carry trees. The alpine tundra’s cold climate or snowy tundra is characterised by reduced temperatures throughout the air and is close to that of the polar climate. Alpine tundra is distinct from arctic tundra such that there is normally no permafrost seen in alpine tundra, however, alpine soils are usually better drained than arctic soils.  

Stunted forests growing at the forest-tundra ecotone (the treeline) are recognized as Krummholz. Alpine tundra converts to subalpine forests below the tree line.

Alpine tundra tends to occur in mountains worldwide. The plants growing close to the ground, like sedges, perennial grasses, cushion plants, forbes, mosses, and lichens, define the flora of the alpine tundra.

The tundra forest or flora is suited to the alpine environment’s harsh and unfavourable conditions, including dryness, snowy tundra, ultraviolet radiation and a limited growing season.

Fun Facts about Tundra World

• In summer seasons, polar bears travel to the tundra to have their infants.

• In tundra, Animals appear to have short ears and tails. In the cold, this allows them to drain little heat. They also appear to have big feet, so they can climb on top of the snow.

• During the winter seasons, Lemmings, small mammals of the tundra world, burrow underneath the ice to eat grass and moss.

• The term tundra comes from the word tunturi in Finnish, meaning treeless plain or barren ground.