Category: Geography Notes PPT

In Geology, laccolith is a sheet-like intrusion that has been inserted between the two layers of sedimentary rocks. Due to the intense pressure of the magma, the overlying strata are forced upward and folded, giving the laccolith a dome or mushroom-like form (or feasibly conically or wedge shape) with a substantially planar base. As time goes on, erosion can form small mountains or hills around a central peak as magma rock is likely more susceptible to weathering than the host rock. 

The laccolith growth can take as little or a few months when related to the injection of a single magma event or up to a hundred or thousands of years by multiple magnetic pulses, assembling sills on top of each other and impairing the host rock steadily. 

Laccolith Definition

A laccolith is defined as the body of igneous rock which has forced itself by the intrusion, in molten conditions between strata of sedimentary rock in such a way as to have raised the overlying strata in a dome shape arc above it. 

Laccolith Formation

Laccolith manages to form at relatively shallow depth and in few cases are formed by relatively viscous magma, such as those that crystallize to granite, diorite, and granodiorite. In such cases, underground may take steadily, giving time for larger crystals to form in cooling magma.  In other cases, less sticky magma (For example, shonkinite) may form phenocrysts of augite at the bottom, then inserted through a vertical feeder dike that ends in laccolith. The rock surface above a laccolith destroys completely, leaving the core mound of igneous rock.

The laccolith is the attribute of the region where the crust is being flattened and the direction of the least stress is vertical, whereas the region where the crust is in pressure is more likely to form dikes as the direction of the least stress is parallel. For example, in Mexico, the laccoliths of the Ortiz porphyry belt was formed during Laramide compression of the region 33 to 36 million years ago.

Laccolith Examples

A renowned example of laccolith is found in Henry Mountain, Utah. 

The largest laccolith in the United States is Pine Valley Mountain in the Pine Valley Mountain Wilderness area near St. George Utah.

Batholith and Laccolith

Batholith (also known as a plutonic rock) is a large mass of igneous rock. It is larger than 100 square kilometres (40 sq mi) in area. The batholith forms from cooled magma deep in the Earth’s crust. The rock is mainly made up of felsic or intermediate rock types such as granite, quartz monzonite, or diorite.

Laccolith

A laccolith is a rock that appears as a sheet-like intrusion and is intruded between the layers of sedimentary rock. The intrusion takes place when the pressure of magma is high enough to move the strata of sedimentary rock in an upward position or to make them fold. This pressure gives the laccolith a dome or mushroom-like appearance Generally, the base of the laccolith is planar.    

The following table shows the difference between Batholith and Laccolith

Batholith and Laccolith Differences

Did You Know?

• Laccoliths are generally formed at a relatively shallow depth and in few cases are formed by relatively viscous magma such as those crystallized to granite, diorite, and granodiorite.

• The surface rock above laccolith often completely erodes, leaving the core mound of igneous rock.

• The laccolith of the Ortiz Porphyry Belt in New Mexico has probably formed during Laramide compression of the region 33 to 36 million years ago.

• Henry Mountain in Utah is a classic example of a laccolith.

• The geology of the Henry Mountain, Utah was first studied by Grove Karl Gilbert in 1875-1876.

The Loo is a strong, dusty, gusty, hot, and dry summer wind from the west that blows over North India and Pakistan’s western Indo-Gangetic Plain. It is especially strong in May and June. Exposure to it often results in fatal heat strokes due to its extremely high temperatures which are usually around 45 °C–50 °C (115 °F–120 °F).

Because of the extremely low humidity and high temperatures, the Loo has a severe drying effect on vegetation, causing widespread browning in the areas affected during the months of May and June.

Origins of the Wind Loo

The Loo is thought to have originated in the large desert regions of the northwestern Indian subcontinent, specifically the Great Indian Desert, the Cholistan Desert, and the desert areas of Southern Balochistan.

The wind Loo comes to an end with the arrival of the Indian monsoon in late summer. This usually happens in the month of June. Before the monsoon, there are brief but violent dust storms known as Kali Andhi (or Black Storm) in some parts of North India and Pakistan.

The presence of monsoon clouds in any location is usually accompanied by cloudbursts, and the sudden transformation of the landscape from brown to green as a result of the ongoing deluge and the abrupt cessation of the Loo can appear “astonishing”.

Adaptations

Water evaporates quickly during this season because the plains of North India and Pakistan are both extremely hot and extremely dry. Although this causes many ponds and lakes to dry out, the extreme dryness of the air can also be used to create evaporation-based cooling systems. Windows shielded with fragrant Khas (/ or vetiver) dry-grass fiber-screens that are kept damp with a simple water-pumping mechanism are quite effective as an inexpensive form of air conditioning and have been in common use throughout the plains of the northern Indian subcontinent for centuries.

Because evaporation occurs at such a rapid rate in extreme dryness, the cooling effect can be quite dramatic, resulting in homes with chilly interiors. However, because the water in the screens evaporates so quickly, it must be constantly replenished from raised tanks or with pumps (that can sometimes be driven by the Loo itself). Any water reservoir that is used must also be protected from the Loo and the sun, or it will quickly deplete.

Effects of Loo Wind 

During the summer months, many birds and animals are killed by the Loo, especially in deforested areas where the Loo blows unhindered and shelter is unavailable. Certain insect-borne diseases, such as malaria, have historically seen a drop during the Loo season, as insect populations plummet. 

Even before the 1897 discovery that mosquitoes transmitted malaria, officials in Asia noticed that the strong winds in Northernmost India’s plains naturally kept the region relatively free of the disease. The loo is often referred to as an evil wind in traditional Indo-Pakistani culture because of its destructive and potentially lethal effects on trees, humans, and animals.

It disturbs the natural living state of animals, affects the crops and trees in forests which in turn has an effect on farmers. In certain cases, if the loo is very strong and hot, it can even add fires to the trees in a forest.

Plants and vegetation don’t get the desired climate necessary for their growth. Maintaining the crops in such weather becomes a costly affair, especially in rural regions.

For children and the sick, as well as pets, avoiding proximity to the toilet is highly advised. During the Loo-affected months, most people want to spend as much time indoors as possible in the afternoons. Heatstroke is often referred to as “loo Lagna” which translates to being “afflicted by the loo”.

Overexposure to the loo or environmental heat can cause heatstrokes, increase the body temperatures which maybe lead to fever, rough skin on the face making it dull, and a consistent feeling of heat in the head. It can also severely dehydrate the body making one feel thirsty more than usual.

Precautions to take in Loo wind

During the Loo season, sharbat is usually sold, since they are widely believed to have a cooling impact on the body and have some defence against Loo-caused heatstrokes. Rose sherbets, khus-khus, shahtoot, bel, and phalsa are among them. Consumption of such sharbat and juices keeps the body hydrated and maintains body temperatures at normal.

Also, regularly consuming lemon water or even water can help to keep the body hydrated for long periods of time and prevent sunstroke in presence of loo winds. One should refrain from going out into the hot weather of Loo. However, if it is very necessary to go out for travel purposes, then cover your hands and face very well and carry plenty of water with you.

Take breaks when traveling for long distances in the loo. Traveling constantly without any breaks in the hot air can lead to excessive loss of water from the body and can severely harm the skin. Sunscreen lotions and umbrellas can also be used while stepping out to avoid tanning and negative effects on the skin because of the loo. 

Choose the outfit with care. It is recommended to wear light fabrics in a loose fit which allows the skin to breathe easily. Tight heat-absorbing clothes should be avoided at all costs. They capture the heat and trap them underneath the skin which causes irritation and rashes on the skin, making it red.

Protecting the vegetation in Loo wind

1. Early morning watering
   It is said that drinking water right after getting out of bed has numerous health benefits for humans. The same is true for plants. The high heat during Loo winds can quickly take the moisture out of the soil and dehydrate shallow roots. Watering the plants early in the morning ensures that plants and crops are sufficiently hydrated before the onset of extreme heat. Apart from this, watering multiple times a day is also a beneficial way to protect the plants from destruction in the hot climate.

2. Plant the Seeds Deeper
   Planting the seeds deeper than normal ensures the roots don’t get dried out due to excessive oppressive heat during loo. The topsoil gets dehydrated quickly due to direct sunlight and high temperatures. If the seeds are planted deeper, dehydration would take more time and the plants would remain protected.

3. Shade Cloth and row Covers
   Using a shade cloth or covering the entire row of vegetation with cloths can help to protect the crops from direct sunlight and hot winds. However, it is recommended to put the covers at some distance from the vegetation to avoid trapping heat.

4. Water Deeply
   Deep watering at the base of the plant is one of the most powerful ways to protect and revive the plants because it forces the roots to go deeper into the ground. Combine this with planting the seeds deep in the soil. Together, these two practices can help protect the vegetation from the harsh effects of loo wind.

When you look at precious gems, stones, and minerals, you will find that some are shiny and some are not. This is because certain substances reflect light in various ways. Some have a “glassy” appearance, and others have a “waxy” appearance. Some are characterised as “dull” because they do not reflect light well. The various ways in which these objects reflect light can be related to a property known as “lustre”.

Lustre is a property that defines how light is reflected on a mineral’s surface. It is one of the properties that mineralogists consider when determining the identity of a mineral.

Different Types of Lustre

The Earth is rich in minerals of various types. Because lustre is a mineral property, it varies greatly, so there are many different types. Mineralogists first categorise lustre into two types: metallic and nonmetallic. Metallic minerals have an opaque and glittering look. Nonmetallic minerals do not resemble metals and are divided into subcategories, which will be discussed further. The following are the different types of lustres:

1. Metallic and Submetallic

Metallic lustre refers to minerals that are opaque, translucent, and have the appearance of polished metal. Different pyrites, which are used to produce coins, gold nuggets, and copper, are common examples. Minerals with submetallic lustre resemble metals but have become less shiny or dull as a result of weathering and corrosion. Sphalerite and cinnabar are some examples. They have the same appearance as metal, but because of weathering and corrosion, they become less reflective or dull. Some examples are sphalerite and cinnabar.

2. Nonmetallic

Nonmetallic lustre refers to the lustre of minerals that do not appear metallic. These are further classified as Adamantine, Dull, Vitreous, Greasy, and so on. Nonmetallic minerals don’t look like metals and have different subcategories, which will be further discussed. 

Nonmetallic can be expressed as a material that lacks metal and possesses characteristics of good electricity and thermal conductivity. These are further divided into different types.

Adamantine

Minerals that have remarkable shine and brilliance and have the hard look of a diamond are called adamantine. These minerals can be transparent or translucent, and the most popular examples are found in jewellery and accessory stores: diamonds and cubic zirconia.

Dull

Dull lustre is also known as “earthy” and is used to describe minerals that have poor reflectivity. The surface of minerals with dull lustre is coarse and porous. Some examples are kaolinite and montmorillonite.

Vitreous

This type of lustre is one of the most frequently seen lustre, which occurs in transparent or translucent minerals with relatively low refractive indices. Some of these minerals are quartz and calcite.

Greasy

The greasy type of lustre can be found in minerals that look like they were coated with oil or grease. These minerals can also be said to resemble fat, and they also feel greasy to touch. Some examples are opal and halite.

What is Metallic Lustre?

The quantity and consistency of light reflected from a mineral’s exterior surfaces is referred to as lustre. Lustre is a measure of how much the mineral surface “sparkles”. Minerals are classified into two types based on their lustre: metallic and nonmetallic. Minerals with a metallic lustre are opaque and highly reflective, with a high absorptive index. Native copper, gold, silver, galena, pyrite, and other minerals with metallic lustre are examples.

To define metallic lustre, one can define it as precious stones and minerals that fall into the categories of shiny stones and not so shiny stones. The reason is that these substances reflect light in different ways, which make some stones  look “glassy” and some may look “waxy”. Metallic lustre is for minerals that are opaque and reflective and have the look of polished metal. 

Why do Metals have Lustre?

Elements are made up of tiny pieces known as atoms. Electrons, protons, and neutrons make up an atom. The nucleus, or centre of the atom, is made up of protons and neutrons. Electrons travel in clusters known as clouds around the nucleus. The electrons farthest from the nucleus are responsible for a metal’s lustre. These outer electrons reflect or bounce light. This gives the metal a glittering appearance. The shiny appearance of certain metals’ surfaces is referred to as lustre. Gold and silver are used to make jewels because they have a perfect gleaming lustre. Polishing a metal piece improves its lustre. This is because polishing eliminates particles that accumulate on the metal’s surface over time.

Gold Mineral Lustre

Gold is one of the most well-known and common minerals, known for its importance and unique properties since the dawn of time. Gold Mineral lustre is the most common and general lustre which is recognized for its value and special properties since the earliest of time. Gold is one of the heaviest minerals. When it is pure, it has a specific gravity of 19.3.

The majority of natural gold specimens discovered since ancient times have been smelted for processing. As a result, fine specimens are highly valued and are worth much more than the normal gold price. More specimens have recently been available to collectors, as more miners have saved some of the larger parts for the collectors market.

In its natural mineral form, gold almost always contains traces of silver, and it can also contain traces of copper and iron. A gold nugget is usually 70 to 95 percent gold, with the rest being mainly silver. Pure gold is a bright golden yellow, but the higher the silver content, the whiter the hue. Most of the gold extracted comes from gold ore rather than gold specimens. The ore is usually brown, iron-stained rock or massive white Quartz, with only minute traces of gold. The ore is crushed to remove the gold, which is then extracted from the ore using different methods.

Gold nuggets, a common type of gold among collectors, are created when erosion causes a large piece of gold to break from its mother rock and be carried downstream in a stream or river. The Gold is tumbled by the rushing water, giving it its distinctive rounded shape. The gold finally settles at the bottom of the water and stays there due to its heaviness. Other nuggets become entangled in the same region, resulting in the formation of a placer deposit.

While silver, gold, and copper have similar electron configurations, we perceive them to have very different colours. Electrons absorb incident light energy and are excited from lower to higher, empty energy levels. The excited electrons will then return to lower energy levels and emit the energy difference as a photon. So, they are the reason for Gold Mineral lustre properties. 

Conclusion

Identifying and categorising minerals is one of the tasks that mineralogists must perform. While a mineralogist can use a high-powered microscope to identify certain minerals, the majority can be identified by physical properties, such as colour, streak, and lustre. Lustre is the reflection of light off the surface of a mineral. Mineralogists use specific terminology to explain lustre. The mineral’s metallic or non-metallic status is one easy way to classify lustre. Minerals with a metallic lustre, such as pyrite, are opaque and shiny. Quartz, for example, has a nonmetallic lustre. The electrons farthest from the nucleus are responsible for a metal’s lustre. These outer electrons mimic or bounce light. This gives the metal a gleaming appearance. The shiny appearance of certain metals’ surfaces is referred to as lustre.

A plant population that has evolved naturally without the assistance of humans is referred to as natural vegetation. For a long period of time, they have also been unaffected by humans. This is what we refer to as virgin vegetation. Cultivated fruits and crops, as well as orchards, are considered vegetation, but not natural vegetation. Plants from a specific area or time period are referred to as flora. The word “fauna” refers to animal species.

Types of Natural Vegetation

The following are the principal types of natural vegetation in India:

1. Tropical Evergreen Rain Forests: Tropical Evergreen Rainforests are located in areas with even more than 200 cm of annual precipitation. They are mostly located in the northeastern states of Assam, Meghalaya, the Western Ghats, Nagaland, the Himalayan Tarai zones, the Andaman Islands and Arunachal Pradesh. They can also be found in the Khasi and Jaintia hills. The trees throughout this area are gaining a lot of height.

Sandalwood, Mahogany, Gurjan, Rosewood, and bamboo are the main trees grown in this region. It does have a multilayered structure due to the abundance of vegetation among all kinds – shrubs, trees, and creepers. Elephants, monkeys, and lemurs are among the species that can be found in these regions.

2. Deciduous or Monsoon Type of Forests: On the lower elevations of the Himalayas, Chhattisgarh, West Bengal, Bihar, Orissa, Karnataka, Maharashtra, Jharkhand, and the surrounding areas, deciduous forests can be found. The rainfall in this region ranges from 100 to 200 cm. Teak is the most common tree in the region. Deodar, Pal Ash,  Blue Gum, Sandalwood,  Sal, Ebony, Arjun, Khair, and Bamboo are among the other trees. Mostly during dry summers and winters, the trees in this forest lose their leaves. These forests are further classified into humid and dry deciduous forests depending upon the availability of water.

3. Dry Deciduous Forests and Scrubs: Such forests thrive in climates with annual precipitation ranging from 50 to 100 centimeters. The Central Deccan plateau, Haryana, Punjab, portions of Uttar Pradesh, Madhya Pradesh, and the southeast of Rajasthan are the most affected.

4. Semi Desert and Desert Vegetation: The annual rainfall in this region is less than 50 cm. This vegetation zone is home to thorny trees, acacia, and Babul. The Indian wild date is commonly found in this region. They have dense flesh and broad roots. Plants in this area hold water in their stems to help them survive the drought. Gujarat, Punjab, and Rajasthan all have this kind of vegetation.

5. Tidal or Mangrove Forests: Rainfall totals only about 50 cm in this region. This vegetation zone is home to thorny acacia, bushes, and Babul trees. Here is where you’ll find the Indian wild date. Large roots and dense flesh are characteristics of this species. This region’s plants store water in their stems to withstand the drought. Gujarat, Punjab, and Rajasthan all have areas with this kind of vegetation. In such forests, the ‘Sundari’ is perhaps the most important tree. Hogla, Pasur, Garan, and other tidal forest trees are significant. This forest is vital to the forestry industry because it provides both timber and firewood. The coastal strip is adorned with palm and coconut trees.

Natural Vegetative Propagation

When an axillary bud develops into a lateral shoot that has its own roots, this is considered as biological vegetative propagation (also termed as adventitious roots). Bulbs, stolons, rhizomes, and tubers are plant systems that allow for natural vegetative propagation. Since specialized organs of vegetative reproduction, such as seeds in annuals, help to withstand seasonally harsh environments, some species of plants that withstand and substantially grow through vegetative reproduction are almost by definition perennial. A clonal community is a plant that survives in a given location by the vegetative reproduction of organisms over a prolonged period of time.

In certain ways, Natural vegetative propagation is a method of survival and growth of the individual’s biomass rather than reproduction. The process of “vegetative development” occurs when an individual organism grows in size through cell multiplication while remaining intact.

Wildlife

Wildlife used to belong to undomesticated animal species, but it has since expanded to include those animals that evolve or live in the wild without being established by humans. In all habitats, wildlife can be identified. Deserts, grasslands, wetlands, deserts, rainforests, and other regions, including the world’s most populated cities, all have unique wildlife.

Although the term is also used to refer to species that are unaffected by human activity, many scientists believe that human activities have a significant impact on wildlife. Humans have traditionally tried to keep society and wildlife apart in a variety of ways, including legal, social, and moral ones. Some species, on the other hand, have adapted to suburban life. Domesticated cats, mice, dogs, dogs, and rats are examples of this. Few religions consider such species to be sacred, and environmental activists have protested against the destruction of wildlife for human benefit or entertainment in recent eras.

Some of the examples of wildlife are given below:

• Gir National Park and Wildlife Sanctuary, also known as Sasan Gir in Gujarat is home to Asiatic lions.

• India is also home to the most magnificent mammal on the planet: the elephant.

• Tigers are generally found in the Himalayan region, in the forests of Madhya Pradesh, and in the Sundarbans of West Bengal.

• The leopard is one of the most important animals of prey.

• The wetlands and forests are home to peacocks, pheasants, ducks, parakeets, cranes, and pigeons.

• The one-horned rhinoceroses live in the swampy and marshy areas of Assam and West Bengal.

• The Tibetan antelope, The yak, the shaggy horned wild ox weighing around one ton, wild sheep, the bharal (blue sheep), and the kiang (Tibetan wild ass) are found in the freezing high altitudes of Ladakh.

• Camels and wild asses are found in arid areas of the Thar Desert, and the Rann of Kachchh, respectively.

• Turtles, crocodiles, and gharials are generally found in lakes, rivers, ponds, and coastal environments.

Uses of Wildlife

For food: People and trappers in the Stone Age depended on wildlife, including animals and plants, for food. In reality, ancient human hunters might just have hunted some species to extinction. In certain areas of the world, fishing, hunting, and collecting wildlife is still a major food source. Hunting and non-commercial fishing are primarily viewed as a hobby or recreational activity in many other countries.

Bushmeat is meat produced through wildlife that isn’t usually considered a game. The increased supply of wildlife as a popular food source in East Asia is decimating communities of sharks, pangolins, primates, and some other animals believed to have aphrodisiac qualities.

As pets and in medicinal ingredients: Others, including parrots and monkeys, are meant for the pet industry and are frequently brought into the United States. Certain Amazon species become famous ingredients in local markets’ traditional medicines. The medicinal value of animal parts is primarily dependent on folklore.

Conservation of Natural Vegetation and Wildlife

Below given points state the reasons for the conservation of natural vegetation and wildlife:

• Forests provide us with oxygen and precipitation.

• Soil erosion is prevented by forests.

• Pollination and seed dispersal are both based on animals and birds for plants.

• Forests supply us with a variety of medicines.

• In industries, a variety of forest products are being used as raw resources.

• They are a constant in the natural world.

• These wildlife communities help to preserve ecological balance.

• Some animals are extinct, and others are on the verge of becoming extinct.

• Endangered animals ought to be safeguarded.

• Wildlife has the same right to exist on this planet as humans.

Initiatives by the Government to Protect Natural Vegetation and Fauna

Pollution, commercial hunting, deforestation to make way for cultivable and habitable land, acid deposits, and so forth. are main causes of threat to nature.

• The Wildlife Protection Act was introduced by the government in 1972. 

• In India, 10 out of the 18 biosphere reserves set up have been incorporated in the world network of biosphere reserves.

• There are 104 national parks, 535 wildlife santuaries, and various zoological gardens in order to safeguard the country’s flora and animals. 

• For the preservation of endangered animals, various government projects, such as Project Tiger, Project Rhino, Project Great Indian Bustard and many other eco-developmental projects have been introduced. 

• The government has been providing financial and technical aid to the Botanical Gardens since 1992.

• The government has also taken actions to protect natural resources, including UNESCO Protected 18  biosphere reserves.

• Various projects and programs have been launched for the protection of wildlife such as Project Tiger, Project Lion, Project Elephant, Project Vulture, etc.

Changes in Natural Vegetation of India

In huge regions of India, the vegetation cover is no longer natural. It has seen significant transformations as a result of a multitude of factors, including the rising demand for arable land, industrial expansion, and mining. The vegetation of the majority of areas has been modified, replaced, or degraded by human habitation in some areas except for some inaccessible locations such as the Himalayas, central India’s hilly region, and the marusthali. urbanization and pasture overgrazing.

Coal is a black solid or sedimentary rock, which is combustible in nature. It has a large amount of carbon in it – almost 50% of its weight. The formation of coal takes a long long time. The first coal-bearing rock is said to have appeared about 350 million years ago. This period was known as the carboniferous period or the “coal-bearing” period. Also, there are extensive coal deposits from the Cretaceous age i,e about 144 million years. Let us take a look at the coal origin and formation.

Biological Origin of Coal

Coal is an organic rock that originated by the accumulation of plant material and also subsequent physical and chemical alteration of the material over a long period of time. The coal has inorganic elements too in the form of mineral matter or ash. The plant materials that eventually form the coal have some primary constituents which have different properties and different decomposition rates. These are:

Different Property and Decomposition Rates

Earlier, the scientists used to believe that as the plant matters are made up of cellulose mostly and cellulose is present in double amounts of lignin, cellulose is the mother substance of coals. But, later, through scientific studies, it was found that when bacterial degradation of peat swamp happens, cellulose decomposes very fast to carbon dioxide, methane, and aliphatic acids. Hence, it was proposed that Lignin was the mother substance of the coals. This is known as the Lignin Theory. 

Evolution of Humic Matter

Wax and resins are the constituents of the plant matter which are more resistant to decomposition and decay. They are fossilized with no change during the coal formation process. The other constituents of the plant matter – cellulose, lignin, and proteins, and minerals are converted into 2 parts – Humic Substance and Inert Carbonaceous Matter. The remnants of the organic matter in peat swamps are first in the solid state which is converted into colloidal material and then in the liquid or gaseous state. 

Order of Decomposition

In the process of coal formation, first, the hydrogen is removed, then the nitrogen, and then the carbon. Carbon is most stable amongst hydrogen, nitrogen, and carbon. When the biochemical decomposition of vegetal matter happens, the result is carbon enrichment. 

Mode of Deposition of Coal

Let us understand the process of coal deposition in detail. 

• Coal is formed mainly from the terrestrial plant material that grows on dry land. 

• The plant debris gets transported by water and then gets deposited under the water in the water bodies. 

• The sediments – organic and inorganic, get settled down gradually.

• This sedimentation process continues till the deposit is covered completely with minerals and sand which results in coal seams.

• Coal has a wide variety because of the varied types of vegetation deposition. 

• The plant debris that accumulates in wet and fluviatile conditions is deposited and is buried by sand, mud, and silt. 

• After the deposition, the metamorphosis of the wood occurs because of temperature and pressure effects. It produces various types of coal.

• The initial transformation of debris material includes various kinds of decay and degradation because of bacterial and fungal action. Slow atmospheric oxidation also takes place.

• The organic material which is water-saturated, spongy, and plant-derived, known as peat, is known as the precursor of coal. This is called peatification – the primary transformation.

• The secondary transformation is a slow process. It includes the aging of Peat deposits under substantially anaerobic conditions, elevated temperatures, and higher pressures. This process is known as Coalification. 

• The Coalification process is the progressive transformation of peat to higher coals.

• Day to day increasing deep burial has a requirement of younger sediment to advance coalification to the bituminous and anthracite stages.

• The pressure that is exerted by the weight of overlying sediments and the heat that is increased by the depth and length of exposure, determines the degree of coalification and the rank of coal.

Factors Determining the Composition of Coal

The factors that determine the composition of coal are:

• The mode of accumulation and burial of the plant debris forms the deposits.

• The age and the geographical distribution of the deposits.

• Structure of the coal forming plants, their chemical composition, and resistance to decay.

• The nature and the intensity of the peat decaying agencies. 

• The geological history of the residual products of the decay of the plant debris that forms the deposits.

Origin of Coal Theories

There are two theories proposed for the mode of accumulation of the plant debris to transform into coal. These theories are – In – situ (Autochthonous) Theory and Drift (Allochthonous) theory.

In – Situ or Autochthonous Theory

There is a popular theory that the plants which compose the coal were accumulated in the large freshwater swamps or peats for many years. This popular theory is known as the autochthonous theory. According to this theory, the coal seams are observed most where the forest grew. The forest land was sinking slowly and the plant matters went underwater gradually. These plant matters did not decompose and were not destroyed. As time passed by, more land submerged and gradually the whole forest was underwater. Again, with the passage of time, the land of the forest came out of the water and this cycle remained repeating. And this eventually resulted in the formation of coal strata and seams.

Drift or Allochthonous Theory

This theory states that the coal strata that is accumulated from plants which are rapidly transported and deposited under flood conditions. As this theory assumes the transportation of plant debris, it is called an allochthonous theory. According to this theory, the plant debris is transported with the flowing water from one place to another and finally gets deposited in the place like swamps, lakes, and seas. These places have suitable conditions for the supply of sediments. An example of this theory is the Indian Coal Seams.

India, the 7^th largest country in the world in terms of area, is the epitome of diversity. It is one of the best examples of diverse topography that can cite almost anything ranging from high-rise mountains and archipelagos. In this section, we will study the prime physical features of the India map. These features will be explained from the prehistoric age to the current geographical map we have seen. Learn the rich geographical features of India here and gather more knowledge to answer questions in your exams.

The Indian Map: A Brief Introduction

India is a country with remarkable topographical features that make it a great subject of study. You will be fascinated to learn that this country has almost every feature for a complete study of different geographical landforms. Ranging from the highest mountain ranges to plateaus, riverbeds to archipelagos, India is rich with such features. Read this section carefully and understand what points you can add to the physical features of India project.

The Origin of India

This is not a topic where you will find historical evidence of the empires and kingdoms. It goes way back to when the entire world had a single landmass divided into two massive segments. The Indian peninsula was a part of the Gondwana land segment. These segments formed due to the plate tectonic movements occurring beneath the sea level. The Indian peninsula was a part of the family that had Australia, South America, and South Africa as members.

The ocean currents and the tectonic actions separated these big landmasses and formed the continents. In fact, they are still moving apart from each other. It took millions of years to float apart from each other and to become a part of the big continents. The special features of India were drawn from the features of Gondwana Land. Some new features also evolved due to such movements of the tectonic plates and changes in the ocean currents.

The Indo-Australian tectonic plate(comprising the Indian peninsula and Australia) started moving north and eventually collided with the Eurasian Plate. This significant movement gave the country we are living in. If you follow the physical landscape of India, you will notice that the Himalayan ranges have formed as a barrier between the Eurasian Plate and the Indo-Australian plate. If you remember the features of the fold mountains, you will understand how the Himalayan Ranges formed due to the collision of these tectonic plates and the folding of the seabed to form a high-rise landscape. This is how India got her physical features. Let us now discuss these features elaborately.

Prime Physical Features of India Map

If you focus on the Indian map, you will find six different segments of physical features. These features are different from each other in terms of physical traits and formation.

1. The Himalayas

As mentioned earlier, the Himalayas are the prime feature of the Indian subcontinent. It is one of the prime physical characteristics of India that controls the climatic conditions of the entire northern part of the country.

The steepest and rugged mountain ranges in the world, the Himalayas stretch from Kashmir to Arunachal Pradesh. It covers almost 2500 km forming a protective arc. It stops the chilly Arctic winds from entering the landmass and keeps the tropical region warm. The width of this landmass ranges from 150 to 400 km. The average peak height is 6000 m in the Greater Himalayas. The same for the Lesser Himalayas is 4000 m.

Himalayan Ranges in Parallel

The Himalayas are made up of three parallel ranges that are split into three categories:

The ‘Himadri,’ or Great or Inner Himalayas: The Great Himalayas, which are perpetually snowbound, have the highest peaks. All of the main Himalayan peaks are included in the Himadri, which has an average height of 6,000 metres. It is one of India’s most visible physical characteristics.

Himachal or Smaller Himalaya: The lesser Himalaya or Himachal refers to the more difficult regions of the mountain range. Himachal Pradesh’s hill stations are also well-known. The average height of these ranges is 3700 to 4500 metres. The Pir Panjal range is the longest.

The Shiwaliks, or Outer Himalayan Range, are lower mountains with altitudes ranging from 900 to 1,100 metres. They are made up of unconsolidated sediments carried down by rivers from the Himalayan peaks.

Himalayan Regional Classification

The Himalayas are divided into regions.

The Himalayas are further separated into western and eastern regions:

• The Himalayan area between the Indus and the Satluj is known as the Punjab Himalaya, although it is also known as Kashmir and Himachal Himalaya in the west and east, respectively. 

• The Kumaon Himalayas are located between the Satluj and Kali rivers in Himalayas.

• The Nepal Himalayas are defined by the Kali and Tista rivers, whereas the Assam Himalayas are defined by the Tista and Dihang rivers.

• The Brahmaputra is the Himalayas’ easternmost frontier.

2. The Northern Plains

India has three main river systems made by the Ganga, Brahmaputra, and the Indus. It is the second most important physical feature of India on map. The rich alluvial deposit makes this place the cradle of civilization. The water flowing from the glacial origin of all these rivers helps civilizations to settle in their banks.

The Punjab plains cover the tributaries of Indus. A major part of this plain lies within the map of Pakistan. The Ganga Plains cover the states of West Bengal, Jharkhand, Bihar, Uttar Pradesh, Haryana, and North India. The Brahmaputra Plains cover Assam and a major part of the north-eastern states.

3. The Indian Peninsular Plateau

Considered as the oldest landform that dates back to the era of Gondwana Land, the Indian Peninsular plateau or the Deccan Plateau covers the Central Highlands ranging from Malwa Plateau to the northern part of the Narmada River. The rest of this landmass is the Deccan Plateau. It is a triangular landmass ranging from the Eastern Ghats to the Western Ghats.

4. The Indian Desert

The vast sand dunes in the arid western part of the country cover the Indian Desert. It ranges from the Aravali Hills to the western corridor of India covering the states of Rajasthan and North Gujarat.

5. The Indian Coastal Plains

The coastal plains of India are one of the major geographical features of India that ranges from the Bay of Bengal to the Indian Ocean and then to the Arabian Sea. The Arabian coastline is divided into the Konkan Coast, the Kannada Plains, and Malabar Coast. The Eastern Coast is divided into the Northern Circar and the Coromandel Coast.

6. Islands

India has two sets of archipelagos. The Andaman and Nicobar Islands, surrounded by the Bay of Bengal and the Indian Ocean, are in the east. The Lakshadweep archipelago lies in the west guarded by the Arabian Sea. It is considered to be one of the special features of India.

Physical Characteristics-Based Classification

The physical geographic elements of the Northern Plain also separate it. It is separated into four regions from north to south: Bhabar, Terai, Bangar, and Kadar.

Bhabar Region: It is located in the Himalayan foothills and is around 8-16 kilometres wide. The area is largely made up of stones and pebbles. The rivers are swiftly flowing here.

Terai: Terai is a 15-30 km broad region south of Bhabar. It is densely forested, and the land is suitable for farming. The water is moving quickly here.

Bangar Region: Located south of Terai, this region is less fertile.

Kadar Region: Located south of Bangar, Kadar is a rich, flood-prone region.

Conclusion

• Prime Geographical Features of the Map of India, the 7^th largest country in the world in terms of area, is the epitome of diversity.

• In this section, we will study the prime physical features of the India map.

• Learn the rich geographical features of India here and gather more knowledge to answer questions in your exams.

• The Indian Map: A Brief IntroductionIndia is a country with remarkable topographical features that make it a great subject of study.

• Read this section carefully and understand what points you can add to the physical features of the India project.