Category: Geography Notes PPT

The dendritic pattern is derived from the Greek word Dendrite which means tree. The pattern itself resembles the branches of a tree and develops gently into a sloping basin with the uniform rock type; the tributaries flow each other from the area because the rock type is the same throughout the entire area. One example of the dendritic drainage pattern is the Caroni River in Trinidad.  

Channels develop in areas where surface runoff occurs and materials can be loosened and transported by the kinetic energy of water. The classification system helps indicate topographic and geologic controls on water flow. 

The Dendritic Pattern

The streams within a drainage basin form certain patterns, depending on the slope of the land, underlying rock structure as well as the climatic conditions of the area. There are four types of drainage patterns: dendritic, trellis, rectangular, and radial. Today, we will learn about the dendritic pattern. The dendritic pattern develops when the river channel follows the slope of the terrain often found in mountainous areas. It is the most common form of drainage pattern and looks like the branching pattern of a tree when joined by tributaries. 

For example, Ganga with its tributaries forms the dendritic pattern in the northern plains. The streams will flow downhill pulled by gravity and come together from a small tributary into a large river. It develops in areas that are underlined by a relatively homogeneous or material, that’s roughly the same throughout and are not a lot resistant and non-resistant rocks and things like that. 

The subsurface geology has a similar resistance to weathering so there’s no apparent control over the direction the tributaries take joining larger trivet streams that are acute angles which means that at less than 90 degrees and that’s how you get the branching effect that we see. On maps, patterns form where there is a pronounced slope to the land surface so that one where we would have a mountain face raining. For example, into a valley, the parallel pattern develops, and regions of parallel elongated landforms like outcropping resistant band rock. Tributary streams tend to stretch out in a parallel fashion following the slope of the surface. Sometimes it indicates the presence of a major fault that cuts across its area of steeply folded bedrock. All forms of transitions can occur between dendritic and trellis patterns. 

You will find different kinds of water bodies on the Earth and the origin of these bodies may be different and similarly the way they are drained, those patterns can also be different. If we talk about the Ganga river system that creates the world-famous plains, before draining into the Bay of Bengal, it follows a particular drainage pattern in its basin. There are different kinds of patterns or systems of drainage that can be found that water bodies usually follow. In this article, we will be discussing one of the most common patterns that are followed by the water bodies. This topic will help you to learn the river system and one of the most famous patterns. 

 

About Drainage

If we talk about drainage, it is a process or a system, or a way through which some liquid is being drained from one place to another. On the other hand, Geography or Geomorphology, if we talk about the drainage patterns or systems, is a system followed by the rivers or streams or lakes, etc. in a drainage basin. It is also called a river system as well and largely depends upon the irregularity of the tectonic plates or the rocks laying under the water body or the land gradient. Based on the Geology or topography of the region, the drainage patterns can be classified into several categories. One of them we’re going to discuss below ie. the dendritic drainage pattern, which is considered as one of the most important and common systems of drainage in Geomorphology.

 

Dendritic Drainage

It is one of the most common drainage patterns found in the world. It appears like branches of the roots of a tree and happens on that lithographic surface which has a uniform rock structure. It appears as a homogeneous structure and thus has a uniform and similar resistance towards the weathering and another phenomenon. In this kind of pattern, the tributaries usually join the larger stream at an acute angle which is less than 90°. The structure of the larger rivers along with their tributaries appears like branches of the tree and forms a V-shaped pattern.

 

The major examples of the rivers system that follows this dendritic drainage pattern are the Amazon river system which is found in South America, the Mississippi river system which is found in North America, the Ganga river system, and the Indus river system which are found in Asia, etc. Besides these, mostly rivers found in Britain also follow this kind of pattern. The map of the Amazon river system is given below where you can see the Amazon River and its tributaries and also tributaries of the tributaries that combination makes this dendritic pattern. 

 

Dendritic Drainage Pattern in India

India is known as a land of rivers where a number of large and small rivers are found and these follow different drainage patterns. Basically, all major types of drainage patterns can be found in India in different regions of the country. If we specifically talk about the Dendritic drainage pattern, it can be found in the Ganga Brahmaputra river system, Indus river system, Mahanadi or Godavari, etc. In the following map, the dendritic drainage pattern of the Ganga river can be observed. Have a look, 

 

Besides these, the rivers that follow antecedent drainage are the Indus, the Satluj, the Ganga, the Tista, and the Brahmaputra. The rivers that follow the consequent system are Godavari, Krishna, and Kaveri. The examples of subsequent rivers are Chambal, Sind, Ken, Betwa, etc whereas Damodar, Subarnarekha, Chambal, Bananas are examples of superinduced drainage. Besides these, trellis drainage, barbed pattern, rectangular drainage or radial pattern, annular and parallel drainage patterns are also found in India.

Environmental science is sometimes also called environmental engineering. It is one of the most prominent fields of study that students opt for these days. The basic definition of environmental science consists of fields such as ecology, biology, chemistry, geology, and much more. It is an interdisciplinary field and that is because it consists of different aspects of social science as well as humanities too. 

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Apart from studying the physical and biological aspects of different characteristics of the environment, this field also consists of certain cultural and social impacts that humans have made on the environment today. Hence, it is really important for students to delve into environmental science study to understand what factors affect the environment. 

How to Define Environmental Science? 

In order to know what is environmental science, one has to understand how it is different from environmental studies. Environmental science can be defined as a quantitative discipline that has aspects of both theoretical and applied science. This field is influential when it comes to informing the different policies of the government in safeguarding the environment all over the world. Environmental studies and environmental science have a lot of differences, the emphasis of which is on the human relationships with the current environment as well as the political and social dimensions pertaining to it.

Importance of Environmental Science

After understanding what is environmental science, students have to figure out its importance. Environmental science is crucial for the following reasons: 

• To figure out a more sustainable way of living. 

• Understanding the behaviour exhibited by organisms under some natural conditions. 

• Educating and making people aware of different environmental issues and problems. 

• Using natural resources in an effective manner without actually causing any harm to the environment. 

• Teaching human beings how important environmental conservation is for the rest of humanity.

There are some other branches of environmental science such as atmospheric science that deals with the atmosphere of the Earth. Ecology is another branch of environmental science that focuses on the interaction of organisms with our environment. It also teaches the impact of certain environmental factors such as water and air pollution on the environment. 

Admission and Eligibility Into Environmental Science Colleges 

One of the most important questions that students have about environmental science and studies is how to get admission to the colleges that have this particular course. For some of the undergraduate courses, the students have to pass their 12th examination and must have a combination of science subjects such as Chemistry, Mathematics, and Biology. However, for the post-graduate courses, students need to have a Bachelor’s degree in Environmental studies or some fields related to that. 

The admission of students happens on the basis of the marks that they have obtained in the examinations before that. Some colleges also tend to have other entrance examinations in order to grant admissions to the students. 

Career and Scope of Environmental Science 

It can be said without a single speck of doubt that the scope of studying the different types of environmental studies can actually have a lot of scope in the employment sector. Both the private as well as government sectors have their own list of reasons why individuals with a degree in environmental science are important for their organizations. 

Environmental science is basically a branch where students will be able to find different ways to protect our environment with the reliable utility of resources. So, individuals have a wide range of opportunities in their careers. They can apply for the roles of environmental engineers, environmental biologists, environmental scientists, environmental journalists, and much more. 

These roles are influential in fertilizer plants, mines, dying industries, textile industries, food processing units, and many other areas. So, the students can have a lot of opportunities to choose from. They can look for work in these organizations which will hire them in a snap. The students having a higher degree in environmental science can actually apply to universities and colleges to teach others about environmental science. 

Salary Scope and Pay Scale 

The salary scope of someone who has a degree in the different components of environmental studies is also pretty high. Students are wanted all over India in different sectors of private and government organizations. These organizations are willing to pay them a very huge amount in order to figure out the resources for safeguarding the environment. The salary of the individual depends on the qualification 

Conclusion 

Environmental science is a pretty lucrative field that has a lot of career opportunities for students. Apart from that, students will be able to study the subjects and find out new ways to preserve the environment in resourceful and effective ways. 

Any preserved remains, impression or remnant of any once-living thing from a previous geological epoch is referred to as a fossil. Bones, shells, exoskeletons, stone imprints of animals or bacteria, amber-preserved artefacts, hair, petrified wood, oil, coal, and DNA traces are just a few examples.

Palaeontology is the scientific study of fossils, including their age, formation process, and evolutionary relevance. If a specimen is above 10,000 years old, it is usually termed a fossil. The oldest fossils range in age from 3.48 billion to 4.1 billion years. The discovery of a geological time frame and the relative ages of different fossils in the 19th century led to the recognition of a geological time frame and the relative ages of distinct fossils. Radiometric dating techniques were developed in the early twentieth century, allowing scientists to quantify the absolute ages of rocks and the fossils they contain.

This article will study what is the fossil record and the importance of the fossil record in evolution scientific theory.

The Fossil Record 

Do You Know What is the Fossil Record?

A fossil record is a collection of fossils that have been studied and placed in taxonomic and chronological order. When organisms die, their remains are encased in earth and rock and gradually replaced by minerals over time. All that’s left is a mineral impression of an extinct animal. Comparative anatomy, radiometric dating, and DNA analysis are just a few of the fields and specialities used to classify and arrange these fossils. Scientists aim to build phylogenies, or trees that describe the links between living and extinct organisms, using data from the fossil record. The fossil record can reveal how different animal groupings have evolved over time.

Charles Darwin Viewed the Fossil Record As:

Along the way, you’ll learn about the origins of primitive “life,” which date back at least 3.5 billion years, as well as the abundance and diversity of life today. The best way to understand this path is to think of it as a result of evolution.

Contrary to common belief, neither the name nor the concept of biological evolution originated with Charles Darwin and his most famous work On the Origin of Species by Means of Natural Selection (1859).

Darwin believed that evolution might be explained by species’ unequal survival as a result of naturally occurring variety, a process he called “natural selection.” This viewpoint holds that organisms’ children differ from one another and from their parents in heritable ways, meaning that the differences can be passed down genetically to their descendants. In addition, given the restrictions of food, space, and other environmental resources, organisms in nature often create more offspring than can live and reproduce. If a particular progeny possesses features that provide it with an advantage in a given environment, that organism is more likely to survive and pass those qualities on to future generations. Populations of creatures diverge from their ancestors when variations develop over generations.

The Fossil Record in Evolution Scientific Theory

1. Humans 

Because of the historical controversy that has surrounded the evolution question, the human fossil record is likely one of the finest recorded. Almost every “missing link” in the network has been discovered, exposing a solid line of fossils stretching from current humans to our ape-like ancestors. The fossils may be distinguished by their distinguishing characteristics, and they may be dated using radioactive isotopes for extremely precise dating. The oldest Homo genus fossils were discovered to be roughly 1.5 million years old. These were the remains of Homo ergaster. Homo ergaster is thought to have spread from Africa and evolved into the species pictured below.

Both Homo erectus and Homo neanderthalensis have unique fossil records, indicating that they competed with modern Homo sapiens. Modern human genomes have been shown to contain traces of genes from Neanderthals, implying that the two species interbred at some point in the past. Humans can be traced back even deeper in the fossil record, all the way to ape-like predecessors who still climbed trees.

2. Whales

Surprisingly, the fossil records of a variety of species have also been nearly completed. Whales, for example, have multiple well-defined members in their fossil record that inexorably lead to present whales. Fossils of semi-aquatic carnivores the size of coyotes that were assumed to live amphibious lifestyles near the beach have been discovered. Later fossils depict a much more aquatic predatory species that looks like a dog but has a much bigger tail and a head specialised to hunting in the water. Around 35 million years ago, there was an animal that was virtually entirely aquatic and lacked hind limbs. After 5 million years, fossils of what appears to be contemporary whales begin to appear.

3. The Oldest Fossil

When it comes to the fossil record of life on Earth, the timeline is significantly longer. The oldest known rocks tested date back to roughly 3.8 billion years. Based on the minerals and hydrocarbons found in particular rocks, scientists have concluded that single-celled life existed roughly 2.7 billion years ago. Single-celled organisms, assumed to be an early ancestor of plant and animal cells, were discovered in the fossil record around 1.6 billion years ago.

The first multicellular life that left plentiful remains, on the other hand, is thought to have existed around 1.2 billion years ago, with a substantial expansion occurring approximately 600 million years ago. This time period is known as the Precambrian, and it marks the beginning of highly sophisticated life. The Cambrian period begins shortly after, with a massive explosion of marine life all across the earth. The Cambrian period saw the emergence of internal skeletons in vertebrates, as well as external skeletons in crustaceans and arthropods. The “Cambrian explosion,” one of the biggest species expansions ever recorded in the fossil record, occurred during this time period.

Terrestrial animals did not appear until the Silurian epoch, roughly 415 million years ago. During the Tertiary period, humans split from our ape relatives around 2 million years ago. The following graph depicts these divisions.

What can be Learned from the Fossil Record?

• Many plant and animal species have either become extinct or developed into modern species since life first began on the Blue Planet. The fossils here assist researchers in learning about ancient flora and animals.

• Palaeontologists learned what they know now about dinosaurs and saber-toothed tigers because of the fossil remains that were uncovered and researched. Fossils give an invaluable record of species that could not have been discovered otherwise since they died long before records were kept. Scientists can reconstruct the appearance of a plant or animal-based on its skeletal structure, learn what the animals ate, and learn where they lived and died.

• Fossil research can also reveal some of the causes that affected evolutionary change. For example, dramatic climatic change wiped off some species, allowing others to adapt to the new environment to live, or resulting in the emergence of a new one.

• Fossil research also reveals information on climate change. For example, scientists knew that a comet had collided with the Earth, drastically altering the circumstances for life and wiping out the dinosaurs. The Ice Age, which wiped out numerous species and altered life on Earth, was caused by yet another catastrophic shift in temperature.

• Scientists figure out how old fossils are by determining their age and looking for other evidence in the same soil layers where the fossils were located. Human remains, as well as plant and animal fossils, provide information on how people lived in the past.

• Plant and animal fossils discovered alongside the ruins of ancient human communities revealed what people ate, how they worked, and how they lived. Scientists can extrapolate that if disease signals are detected in plant or animal fossils, the people of that age may have had the same condition.

• Understanding what people ate can reveal details about their lifestyles, such as whether they hunted, raised livestock, or started producing crops for meals. A fossil layer might also contain objects from ancient societies, such as tools or pottery, which tell scientists about the way people lived at the time.

Did You Know?

When an organism is buried, it goes through a process called permineralization. Mineral-rich groundwater fills the empty spaces within an organism (spaces filled with liquid or gas during life). Minerals precipitate from the groundwater and fill in the voids. This activity can take place in very small places, such as within a plant cell’s cell wall. Permineralization on a small scale can result in extremely detailed fossils. The creature must be covered by silt soon after death for permineralization to occur; otherwise, scavengers or decomposition will destroy the remnants. 

The degree to which the remains have decomposed when they are covered defines the fossil’s eventual details. Some fossils are just skeleton bones or teeth, while others have evidence of skin, feathers, or even soft tissues. It’s a type of diagenesis.

Granite is a type of igneous rock which forms when the magma cools down slowly underground. It comprises mainly the minerals like quartz, feldspar and mica. Some granites contain hornblende and augite, although in small amounts, along with the main ingredients. Accessory ingredients of apatite, hematite, rutile, tourmaline and zircon are also constituents of granite rock. Biotite and other ferromagnesian minerals are also present sometimes in granite. Granite igneous rock usually is pale grey, white or pink in colour which depends on the colour of their constituent feldspars. For example, in the presence of pink microcline feldspar, the granite looks pink. Granite mainly occurs in the form of huge batholiths, stock and sometimes laccoliths.

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Constituents of Granite

Granite igneous rock consists of minerals like K-feldspar (orthoclase, microcline and perthite) about 50 to 80 per cent, quartz about 20 to 40 per cent, Na-plagioclase and mica(s) such as biotite and muscovite. The intergrowth of albite or oligoclase with a microcline or orthoclase host results in the formation of mineral perthite.

The feldspars are the dominant components of granite. They can easily be identified on the basis of the appearance, colour and cleavage properties of granite. Quartz is generally anhedral and is usually present as fillings at interstices between the other mineral constituents while overriding its own characteristic crystal shape. In general, quartz is colourless or smoky. It is identified by its hardness, glass-like appearance, conchoidal fracture and lack of cleavage property. The constituents like biotite, hornblende and muscovite in granite can be distinguished by flaky black or silver colour, black dark green grains or prism characteristics.

Various igneous rocks especially the granodiorite, gabbro and diorite are often wrongly designated as granites by architects and builders. However, they are petrologically defined and cannot be considered commonly as granites. Granites are used commonly in buildings, as decorative stones, for kitchen stall surfaces, tiles, modern sculptures, engineering, rock climbing etc.

Granite Composition

Granite consists of minerals and rocks, dominantly quartz, potassium feldspar, mica, amphiboles and small traces of some other minerals. Granite comprises 20-60 per cent quartz, 10-65 percent feldspar and 5-15 per cent mica(s). The presence of different minerals in different proportions gives the granite different colours and textures.

The variation in proportions of differently coloured minerals in granite comes from the original source of molten rock that was cooled to form the granite. For instance, if we consider a molten rock that was abundant in potassium feldspar, it will be more likely to set into granite with salmon pink colour. While, if it was rich in quartz and minerals that make up amphibole, it would be a black and white speckled granite which we often see on the kitchen stalls and countertops.

Following are the typical effects of different constituents on the granite colour and appearance:

• Quartz – milky white colour

• Feldspar – off-white colour

• Potassium Feldspar – salmon pink colour

• Biotite – black or dark brown colour

• Muscovite – metallic gold or yellow colour

• Amphibole – black or dark green colour

The minerals listed above are responsible for the colours we see in granites generally. In the next section, we will talk about the structural features of granite.

Granite Structure

The term Granite is derived from the Latin word ‘granum’ which means grain. This is related to the coarse-grain-like structure of the rock. As the granite rocks consist mainly of feldspar, quartz, mica and amphibole minerals, they form interlocking between them. The equigranular matrix of feldspar and quartz usually form the lighter portions in the granite structure while minerals like biotite and amphibole (or/and hornblende) form the scattered darker portions. Sometimes, few individual crystals become larger than the groundmass. The texture formed in this case is known as porphyritic and such rocks with the porphyritic structure are known as a granite porphyry. Light-coloured and coarse-grained igneous rocks are often called Granitoid in general and descriptive fields. Granitoids are classified for their specific types through petrographic examination. The mineralogy of the granitic rocks is the deciding factor for their colours which can be predominantly white, pink or grey typically. 

Uses of Granite

Being one of the world’s toughest substances, granite has been in use in various ways for a long time. Apart from its use in the construction of monuments and buildings, granite is also useful in curling balls and gym walls for the training of mountain climbing.

Let’s see the different uses of granite in detail:

• Building Monuments: In order to live long lives and create beautiful designs to the structures like temples, gravestones and monuments, they are usually made from granite. Although, in early times, the unavailability of advanced equipment made the carving process of granite quite difficult and laborious. Hence, such stones were used only in important structures.

• Jewellery: Some granites are quite rare and exceptionally beautiful. Hence, they are used as gemstones in jewellery. An example of such granite is the K2 Azurite which is found in the Himalayas, has a blue tint and is a rare stone.

• Fireplace Mantle and Floor: Granite makes an ordinary fireplace mantle more attractive and suitable for being used as a place of gathering with friends and family. Also, granite tiles are preferably better than other options for perfect, smooth and nice-looking flooring. The availability of granites in different colours and textures is an add-on for suiting the different preferences of people. As it is really hard, it is exceptionally wear-resistant. Also, it is bacteria resistant and easy to clean. One could easily keep such flooring neat and clean with regular sweeping and mopping.

• Bathrooms, Shelves, Tabletops, Basins: Kitchen tops, tabletops and shelves look more elegant while maintaining strength when made up of granite. They are also cleaned very easily and look really stylish in appearance. Also, granite is completely water-resistant. Granite sinks, angular basins and modern or pedestal sinks are some more applications of granite in kitchens and bathrooms.

Do You Know?

• At ambient pressure, dry granite melts at around 1215 to 1260°C. However, in the presence of water content, it gets melted around 650°C at a few hundred megapascals of pressure.

• The primary permeability of granite is poor overall. However, the secondary permeability due to the presence of cracks and fractures is very strong.

Conclusion

We get to know all the information related to granite rock such as what is granite and its usage. Granite is an igneous rock that has grains large enough to be easily visible to naked eyes. The two main constituents of granite are feldspar and quartz. Apart from these, granite also consists of other compounds such as amphiboles, mica, etc. in small and different proportions. Granite is mainly used in flooring, decorating purposes and in jewellery also.

Human settlement in that place, particularly where the people live their livelihood. Human settlement refers to the totality of the human community which involves the social, material, organizational, spiritual, and cultural elements that sustain within it. Any form of human dwelling, be it the smallest house to the largest city, the group of people that reside and pursue their life goals, are to be understood as settlement. Human settlements are of different forms, which can be permanent or temporary, rural or urban, mobile or sedentary, disseminated or in agglomerated form. 

Human Environment Settlement Transport and Communication 

Settlements are those places where people build their own homes. A human can settle in those places on a permanent or temporary basis. With settling in the places, the people are required to move from one place to another for trade here comes the definition of Transport. 

Transport is the means of traveling which is made convenient for the people to move from one place to another. The four main means of transport are – the roadways, the railways, the waterways, and the airways. 

After the transport comes the communication system which is another important facet of a settlement. Communication is the streamlined process of conveying any message to others. Mass media means communicating with the mass of people through newspapers, radio, or television.

Settlement Definition Geography 

In geographical definition, a settlement is a place where people live and conduct their livelihood. Settlements may be small as a single house in a remote or a distant location or it can be an area as large as a megacity (where over 10 million residents reside together).

A settlement can be both permanent or temporary settlement. An example of a temporary settlement is a refugee camp, used by armies. However, a temporary settlement may also become a permanent settlement over time. This has happened to many refugee camps which have been built in conflict zones.

Temporary Settlement examples can be cities and towns, where the families can stay for years with their families. 

Settlements are usually developed to perform a specific function. For example, the settlement in  Southampton is for conducting port functions.

Early Man Communication

Early Man uses the following to communicate better: 

Ancient Means of Transport Pictures

House Boat

Tonga

Trams 

Hath Rickshaw

Gauge Trains

Palki

Types of Settlement in Geography

Classification of the settlements in Geography:

Settlements can be classified according to their pattern, size, and housing density. They are also to be classified according to the functions which they perform.

• Classified according to the pattern: There are 5 types of settlement classified according to their pattern – isolated, dispersed, nucleated, and linear.

• Classification according to size and housing density: According to Size and Housing density:

Rural settlements are small houses and have low housing and population densities.
Urban settlements are the larger houses and have many houses built close to each other.

• A farmstead is the two or more homesteads that usually are dispersed in farmland.

• A hamlet is made up of several dispersed, nucleated, or linear homesteads with local shops, schools, or other service centers that are occupied by few hundreds of persons.

• A village, which is like a hamlet, may be dispersed, nucleated, or both.

• Towns are urban settlements are of up to several thousand persons. Houses are built together and the emphasis is more on secondary and tertiary rather than on the primary occupation. 

• Cities are the major towns of a country, where the major state capitals have administrative functions. 

• A conurbation that grows when two or more towns or parts of those towns have grown and joined together to form a big urban area of 1 million persons or its whereabouts. 

• Megapolis is the several cities or conurbations which have grown around the years and which have joined together to form a large sprawling urban settlement. 

We usually see the Earth from the outside. We see different types of landscape structures, plains, plateaus, grasslands, deserts, beaches, islands, forests or wildlife, etc. but have you ever wondered what can be found inside the Earth? All the things we see outside or use in our daily lives are formed because of the internal processes of the earth along with external factors. Here, we will be focusing on the inside of our Earth. We will learn about the rocks and minerals found inside our Earth, their uses, the classification of rocks, and various other related concepts. 

These rocks and minerals are very useful for us and are used in various processes and products. These notes will serve the needs of students who are looking for Class 7 Geography Chapter 3 notes. 

Rocks and Minerals

These are said to be building blocks of Earth which forms various kinds of landscapes on Earth as well as provide a number of resources as well. Rocks consist of minerals and these rocks are mined to extract minerals because these have Important properties and commercial value. There is no specific structure or chemical composition of rocks but minerals do have definite structure or other properties. Each rock can consist of one or more minerals. Rocks can be formed because of various geological processes and during these processes, various minerals get collected in one rock. When rocks are mined, these are called ores and the remaining rock after extraction of minerals is called tailing.

Uses of Rocks and Minerals

• These are used in everyday life around us.

• Rocks are used for making roads, buildings, and other construction purposes.

• Some rocks which are precious are used as gemstones and some small rocks are also used in games as well.

• Minerals are used for energy purposes such as coal, petroleum, etc. whereas others like fluorite, copper, talc, kaolinite, zinc, gold, diamond, etc. are used for making different kinds of products in the manufacturing industries from paper to jewellery products, minerals are used.

Difference Between Rocks and Minerals

Classification of Rocks

The various types of rocks are mentioned below. 

Igneous Rocks

The rocks formed because of the solidification or cooling of the lava from the volcano are known as Igneous rocks. These are said to be the first and earliest rocks to be formed and other rocks are made from these rocks, thus these are also known as the primary rocks. These rocks are also considered magmatic rocks because of their formation from the magma or also called volcanic rocks because of the relationship with a volcano. These can be divided into the following two types:

These are those rocks that solidify under the crust of the Earth along with the presence of other existing rocks and it cools slowly and rocks become coarse-grained. The rocks which form deep in the crust and are coarse-grained are termed plutonic or abyssal rocks whereas the rocks which form under the crust but near the surface and are medium-grained are termed subvolcanic rocks or hypabyssal rocks.

The types of rocks which solidify above the crust of the Earth or on the surface outside are called extrusive Igneous rocks. Here, the process of cooking is not slow as compared to the intrusive one. They follow a quick solidification process because of the outside temperature present in the region thus, they are of fine quality and glassy texture.

Examples of Igneous Rocks

The first image is of Basalt which is an example of extrusive Igneous rocks and is dark in colour and finely grained whereas the other image is of coarse-grained rock i.e Diorite which is an example of intrusive igneous rocks. Other examples are Dacite, Diabase, Gabbro, Obsidian, Granite, Peridotite, etc.

Sedimentary Rocks

These are the rocks that formed on or near the surface of the Earth because of geological processes such as erosion, weathering, dissolution, precipitation or lithification, etc. And usually have distinctive layers of bedding. They can be divided into three types:

These sediments are carried in rivers or deposited in oceans or lakes and with time when the water disappears, the rock forms. Examples: sandstone, limestone, shale, etc.

• Clastic Sedimentary Rocks

They are made up of clasts of the pre-existing rocks and the names of such rocks depend upon the size of the clast or grain.

• Biologic Sedimentary Rocks

When a large number of living species die then such kinds of rocks form. Chert or limestone are formed in this way.

Examples of Sedimentary Rocks

 

The first image is of limestone and another black one shale. Breccia, Chalk, Caliche, Chert, Conglomerate, Coal, Diatomite, Flint, limestone, etc. Are the other examples.

Metamorphic Rocks

These are the rocks that are formed from igneous or sedimentary rocks or even earlier metamorphic rocks which are formed due to high pressure, high heat, or other factors. The metamorphism process leads to the transformation of the existing rocks into another form. They are of three types:

These include phyllite, schist, gneiss, quartzite, or marble.

• Foliated Metamorphic Rocks

These are the rocks formed because of the parallel arrangement of certain minerals under pressure and are of platy or sheet-like structure.

• Non- Foliated Metamorphic Rocks

They do not have platy or sheet-like structure and grains do not align even after having so much pressure.

Examples of Metamorphic Rocks

The first image is of Gneiss and the other one is Anthracite. Other examples are Amphibolite, Hornfels, Marble, Lapis Lazuli, Novaculite, Quartzite, Soapstone, etc.

Rock Cycle

It is a cycle of various processes that lead to the formation and transformation of various types of rocks inside or outside the crust of the Earth. The three types of rocks which are formed are called igneous, sedimentary, and metamorphic due to various geological factors such as melting, cooling, heat or pressure, erosion, weathering, compacting and cementing, etc. When the heat and temperature inside the crust of the Earthrise, the magma forms which comes on the surface in the form of lava. When this lava hardened inside or outside the surface of the Earth becomes igneous rocks and when these igneous rocks erode into sediments because of various processes leads to the formation of sedimentary rocks and when these two rocks go under extreme pressure or other processes lead to the formation of metamorphic rocks which eventually are a transformation of already existing rocks.  These metamorphic rocks can be eroded further to form sedimentary rocks or can be melted into magma. Thus this cycle continues and these rocks go on the interchange from one type of rock to another. Our earth has several favourable conditions which lead to the formation or interchangeability of these rocks such as wind, water, tectonic plates, and their movements, heat or pressure, subduction, etc.

So, now we have covered the facts about Earth and have seen what does happen inside it. 

Conclusion

Thus, here in this article, we have covered Chapter 3 of Class 7 Geography i.e. Inside our Earth. These notes will be useful for those who are in Class 7 or even the students of upper classes to understand the basic concepts. These will be helpful for those who find it difficult to read the chapter in the book and make notes out of it. has eased your work by providing you with these crisp as well as comprehensive notes which will surely help you to understand the concepts properly as well as in revising the whole chapter quickly. You can check out notes of all other chapters or topics and other subjects as well on our website. These are created and prepared by the subject matter experts of after thorough research to help you in your studies. We believe that these notes will surely help you to grow.