Category: Geography Notes PPT

A rapid round and round movement of a column of air in a cylindrical or funnel shape are called a Whirlwind. The movement is continuous and the intensity of the wind whirl increases over the duration if weather conditions are unfavourable. The whirlwind of activity is very impulsive and can drastically change overnight. A windwhirl can also be a violent or destructive force or agency that is accompanied by a loud roaring noise.

Features of a Whirlwind 

1. The columnar vortex of rapidly swirling air has a small diameter.

2. The whirlwinds happen more often than one may assume in the form of small eddies.

3. Not every wind whirl can be applied to the atmospheric vortex rather they are due to sand, dust, hay, leaves, snow etc.

4. Some whirlwinds cause more turbulence and their features are more prominent in the atmosphere and the effects can be extreme.   

5. The atmospheric pressure at the centre of the whirlwind is relatively lesser.

6. Usually, the axis of rotation of the whirlwind is vertical and in some portions of the wind whirl, it can even be inclined. 

7. The rotational direction of the whirlwind which is smaller can be both clockwise and counterclockwise.

8. The wind and outside forces and agencies direct the direction of the rotation in case of larger or major whirlwinds. 

Types of Whirlwind 

All the types of whirlwind reach the ground and it can occur in open landscapes or even in cities with skyscrapers. There are two types of the whirlwind and it is divided as the greater or major whirlwinds and the lesser or the minor windwhirl.  The criteria for division of them is based on the formation, speed and intensity of the wind during the windwhirl. 

1. Major Whirlwind-  The atmospheric vortex of the swirling air can constitute a continuum and are indefinite and easily identifiable. It includes;

1. Waterspouts – The columnar vortex in this case occurs over a water body like the oceans.  

2. Tornadoes – It is also called a cyclone or twister. It also has similar features like a whirlwind. The volume of air in case of a tornado rotates violently and is in contact with both the ground that is the earth surface and the cloud in a cumulonimbus form which is basically a dense cloud that is towering vertically downwards. 

3. Landspouts – Forms during the growth stage of the tornado in a cumulus congestus cloud and a swirl of air rise vertically like a whirlwind. 

The formation of a major whirlwind is when the funnel forming from the cloud is clearly visible when the storm starts to spin in combination with the high altitude winds. It lasts for many many hours and interrupting such a larger whirlwind is very difficult. Supercell thunderstorms and other powerful storms are seen prior to a major whirlwind.

2. Minor Whirlwind – Formation of the minor whirlwind occurs when local winds start to spin on the ground causing a funnel to form and pick up snow, dust and other debris that makes a visible swirl like a whirlwind. It lasts for mere minutes and when it encounters a building it can be easily interrupted and thus stops. The minor whirlwinds are dust devils that can travel even from areas that are far across. Small, semi-powerful “wind blasts” are seen prior to such minor whirlwinds.

Safety During Major and Minor Whirlwinds

Even though minor whirlwinds are less dangerous and do not create more havoc than the larger major ones. But due to dust devils, a kind of minor whirlwind many deaths have been reported due to it so one must ensure safety during all times when there is a probability of a whirlwind. Since prior to the whirlwinds weather conditions indicate its arrival we can prepare for our safety.

1.  Going to a room with no windows like the basement or any rooms on the lowest floor, even a bathroom, closet, or the centre hallway will be a safe place.

2. Cover your body with a blanket, mattress or a sleeping bag and if possible hide under any sturdy surface below the desk or a bed.

3. Ensure to keep an emergency kit that should include water, medication, over the counter drugs,  non-perishable food at your disposal.

4. Be ready to evacuate if the situation is out of hand one must displace.

5. Do not stay put in a vehicle when you are warned of the danger.

6. Always stay updated about the weather conditions which is the most important step to be prepared for the above-mentioned steps. 

Conclusion

Whirlwinds are a natural phenomenon of the earth due to atmospheric changes but when the condition is extreme it becomes dangerous and one must prepare to defend themselves in such situations. Being prepared for any emergencies and having a place to hide out and stay away from the possibility of a major whirlwind and even the minor one can with time become a critical reason for survival. Ensure the safety of your family members and all the ones around you. 

Everything that takes up space is classified as matter. Air is unavoidable for our existence. The atmosphere is a blanket of air that covers the world. It is among the most vital elements for the existence of life since no life can survive for a single pulse of time without it. It is necessary for all creatures to survive. Let us learn about “what is air made of” and air composition. Also, air influences abiotic environmental components such as wind, rain, and climate.

The atmosphere, usually known as air, is a combination of different gases. When we think of air, the first thing that comes to mind is oxygen, which is necessary for life on earth to survive. However, oxygen is not the only important gas present in the air. Other gases are equally crucial in the maintenance of life. Let’s take a closer look at the composition of the air that allows life to exist on earth.

Air Composition in Atmosphere

The atmosphere of the Earth is made up of a combination of gases called air. These gases are colourless and odourless. In the atmosphere, these gases combine to form a mixture of gases. It is made up of 78 % nitrogen, 21% oxygen, and 1 % other gases and water vapour. As we move up through the levels of the atmosphere, the composition of the air does not change. The number of molecules present in the air is what changes. The number of air molecules decreases and becomes smaller, as we go up. The moisture content varies from location to location. As compared to wetlands, arid places have less moisture content. The amount of water vapour or moisture in the air fluctuates. Air’s maximum moisture carrying capacity is primarily determined by temperature. Until you reach a height of around 10,000 m, the composition of the air remains unchanged.

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Percentage of Gases in Air

Nitrogen is the most abundant naturally occurring gas, accounting for approximately 78% of air. With a prevalence of roughly 21%, oxygen is the second most abundant gas in the air. Argon, an inert gas, accounts for 0.93 % of the total composition. The atmosphere contains trace amounts of carbon dioxide, neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, water vapours, and ammonia. Now, let us talk about how these gases are produced and their various roles in our environment.

• Nitrogen: Nitrogen makes up 78% of the air in the atmosphere. The nitrogen cycle transfers nitrogen to plants, animals, and the environment.

• Nitrous Oxides: When nitrogen oxides interact with water droplets in the air, they produce nitric acid, which contributes to acid rain.

• Oxygen: Oxygen accounts for 21% of the atmosphere. It is extremely reactive and forms compounds with a wide range of other chemicals, and it is required for living creatures to breathe.

• Ozone: The ozone layer, formed by ozone gas in the stratosphere, is critical for the survival of life on Earth’s surface.

• Argon: Argon makes up around 1% of the atmosphere and is mostly produced by the breakdown of potassium in the Earth’s crust. It does not react with other substances since it is an inert gas.

• Water Vapours: Water circulates through all of Earth’s systems in its three states, solid, liquid, and gas. Since it can trap heat, water vapour in the atmosphere acts as a greenhouse gas.

• Carbon Dioxide: Carbon dioxide makes up about 0.03 % of the atmosphere naturally, but it is growing as a result of the combustion of fossil fuels. Carbon dioxide is used by plants and eubacteria during photosynthesis. Through breathing, humans, other animals, and plants contribute to the air. It is a heat-trapping greenhouse gas. 

• Carbon Monoxide: Carbon monoxide in the atmosphere is caused by the combustion of gasoline in automobiles, volcanoes, and forest fires. It’s a lethal gas.

• Methane: Landfills, animals and their manure, and oil and gas wells, all emit methane gas into the atmosphere. It is also produced during the decomposition of organic matter. It is a heat-trapping greenhouse gas.

• Sulphur Dioxide: When coal and oil are burnt, sulphur oxides are created. It is also emitted by volcanoes. Sulphuric acid is formed when sulphur oxides in the atmosphere react with water droplets. Sulphuric acid is a component of acid rain.

Various Properties of Air

As already stated, gases are matter. Gases, like every other matter, have particular features. The following are some examples of frequent properties.

• Colourless and Odourless: Air is usually colourless and odourless. It’s an impenetrable substance that can only be felt. All living things require oxygen to survive. Moving air is referred to as wind.

• Occupy Space: It is a blend of many gases. As a result, they, like all matter, occupy space. A balloon expands when blown because the air poured into it fills the empty area. 

• Exerts Pressure: It has weight, and air pressure is the force exerted by the weight of air. This combination of gases near the surface is denser than at high elevations due to gravity. That explains why the gaseous atmosphere is thinner in the mountains than at ground level.

The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and forms its planetary atmosphere, and is held in place by gravity. The Earth’s atmosphere protects life on the planet by maintaining surface pressure that allows liquid water to remain, absorbing ultraviolet solar radiation, warming the surface through heat retention, and reducing temperature extremes between day and night.

Earth and Atmospheric Science

The study of the atmosphere and its various inner-working physical processes is known as atmospheric science. Meteorology is the study of the atmosphere’s chemistry and physics, with an emphasis on weather forecasting. Climatology is the study of long- and short-term atmospheric changes that characterize average climates and how they evolve as a result of natural and anthropogenic climate variability. The analysis of the upper layers of the atmosphere, where dissociation and ionization are significant, is known as aeronomy. The area of atmospheric science has been expanded to include planetary science and the study of the atmospheres of the solar system’s planets and natural satellites.

Experimental instruments used in atmospheric science include satellites, rocketsondes, radiosondes, weather balloons, and lasers.

Oceanic Sciences 

The mechanics, chemistry, and biology of marine environments are all covered by ocean sciences. Ocean circulation, energy dissipation, marine biology, ecology, biogeochemical cycles, water mass formation and movement, ocean temperature, and salinity, and marine carbon and carbonate chemistry are all topics covered in this area.

Atmospheric Scientist

Atmospheric scientists can work in nearly any area that has to do with the atmosphere. They are more than just meteorologists and weather forecasters; their credentials enable them to conduct research and analysis of the environment in the future, present, and past, ranging from major weather systems to minor impacts on other biological life.

What do Atmospheric Scientists do?

The word “atmospheric science” refers to anyone who studies the atmosphere of our earth. Although the topic includes meteorology (the study of weather), it is not the only aspect of it. Atmospheric scientists will examine the weather and forecast what it will be like in an hour, a day, a week, or the following season. An Atmospheric Scientist, for example, will have the experience to understand the mechanism that will lead to those two phenomena in the first place and will predict when they are supposed to occur, while a meteorologist will understand and predict the results. They’ll study regional trends and create a map of the overall scene, including the causes and effects.

They can work in public health, researching air quality and its effects. This is frequently unrelated to the weather. They may also be able to forecast long-term drought cycles and provide mitigation advice. Short-term weather is just a small part of this job, once again.

Meteorologists concentrate on the current, while atmospheric scientists look back at older data to create an image of past climate, weather, and atmospheric conditions. They are more likely to research historical data (paleoclimate data), such as tree ring information, to determine the composition of the atmosphere. They’ll look at chemistry, climatology, and the nature of weather systems on this planet and those in the solar system, as well as physics.

In India, there are various institutes which offer atmospheric science degrees to the students which are related to the field of earth and atmospheric sciences. Most jobs in atmospheric science include a bachelor’s degree in meteorology or a closely related earth science field. Atmospheric scientists need a master’s degree at the very least, but a Ph. D. is normally needed for research positions.

Atmospheric and Oceanic Sciences

Princeton University and the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory (GFDL) collaborate on the Program of Atmospheric and Oceanic Sciences (AOS). Graduate students, postdoctoral researchers, visiting researchers, permanent research staff, and professors are all hosted by AOS, which is an independent program within the Department of Geosciences. 

Meteorology Programs

Meteorology is a branch of atmospheric science concerned primarily with weather processes and forecasting. The physical, dynamical (a force that causes change or motion), and chemical state of the Earth’s atmosphere, as well as interactions between the atmosphere and the Earth’s surface, are all studied in this area.

To pursue a career in meteorology, one must possess ample interests as well as a high level of education. Meteorologists have a variety of lucrative career options.

Various Meteorology Programs are Enlisted below:

Calcite mineral forms rocks and has the chemical formula CaCO₃. It is widespread and can be found in sedimentary, metamorphic, and igneous rocks all over the world. Some geologists consider it a “ubiquitous mineral,” meaning it can be found anywhere.

Calcite is the most common form of calcium carbonate and is known for its varied and beautiful crystals. Calcite often occurs as scalenohedral and can be commonly twinned as heart-shaped or butterfly twins. The calcite crystals are generally found as rhombohedral terminations; however, there are shallow rhombohedral terminations, also known as nailhead spar.

Calcite is the main component of limestone and marble. These rocks are extremely common and account for a sizable portion of the Earth’s crust. They are one of the world’s largest carbon repositories.

Optical Spar is a highly transparent calcite. It is usually found as spectacular crystals, which are massive, either as marble or as limestone. The calcite can also be seen as earthy aggregates, fibres, nodules, and stalactites. The specimens of calcite specimens can occur in igneous rocks, hydrothermal veins, and metamorphic deposits.

Various Forms of Calcite

There are various forms of calcite that are found in multiple parts of the world.

• Calcite as Oolitic Limestone: Oolitic limestone, a form of calcite is found in Tyrone, Pennsylvania, approximately ten centimetres in size.

• Calcite as translucent onyx: Translucent Onyx, a form of calcite is found in Tecali, Mexico, approximately ten centimetres in size.

• Double refraction in calcite: Iceland Spar, a form of transparent calcite, is found in Chihuahua, Mexico. This specimen exhibits excellent double refraction and is approximately ten centimetres in size.

• Calcite as calcareous tufa: Calcareous Tufa, a form of calcite is found in Mumford, New York, approximately ten centimetres in size.

• Calcite as travertine: Travertine is a form of calcite found in Tivoli, Italy, which is approximately ten centimetres in size.

• Picasso Stone: Picasso Stone, a marbled variety with brown and black marks, is often cut and polished as cabochons to produce stones in jewellery and ornamental crafts.

• White calcite as marble: Calcite in the form of white marble is found in Tate, Georgia, approximately ten centimetres in size.

Calcite Mineral- Natural Occurrence

Calcite is a common constituent of sedimentary rocks, mainly limestone, which is formed primarily from the shells of dead marine organisms. Limestone makes up about 10% of sedimentary rock. It is the main mineral found in metamorphic marble. It can also be found as a vein mineral in hot spring deposits, stalactites and stalagmites in caverns, volcanic or mantle-derived rocks such as carbonatites, kimberlites, and rarer cases, peridotites.

Calcite is a primary constituent of the shells of many marine organisms, including plankton (such as coccoliths and planktic foraminifera), the hard parts of red algae, some sponges, brachiopods, echinoderms, some serpulids, most bryozoa, and parts of some bivalves’ shells (such as oysters and rudists).

Calcite can be found in spectacular form in New Mexico’s Snowy River Cave, where microorganisms are credited with natural formations. Trilobites, which went extinct a quarter billion years ago, had compound eyes with lenses made of clear calcite crystals.

Calcite Formation Process

Calcite formation can occur via a variety of mechanisms, ranging from the classical terrace ledge kink model to the crystallisation of poorly ordered precursor phases (amorphous calcium carbonate, ACC) via an Ostwald ripening process or nanocrystal agglomeration.

Acc Crystallisation Can Take Place in Two Stages:

First, the ACC nanoparticles rapidly dehydrate and crystallise to form individual vaterite particles. Second, the vaterite undergoes a dissolution and reprecipitation mechanism, with the reaction rate controlled by the calcite surface area. The second stage of the reaction occurs at a rate that is approximately ten times slower. Calcite crystallisation, on the other hand, is pH-dependent and Mg-dependent in solution.

During mixing, a neutral starting pH promotes the direct transformation of ACC into calcite. When ACC forms in a solution with a basic initial pH, it transforms to calcite via metastable vaterite, which forms via a spherulitic growth mechanism. A surface-controlled dissolution and recrystallisation mechanism transforms vaterite to calcite in a second stage. Mg has a significant effect on the stability of ACC and its transformation to crystalline CaCO₃, resulting in the formation of calcite directly from ACC.

What is Calcite Chemical Formula?

Calcite Formula: CaCO₃

Calcite Chemical name: Calcium Carbonate

Calcite Mineral – Physical Properties

Calcite Production

The major steps for Calcite production are as mentioned below:

Step 1: Crush the incoming minerals and transfer them to ball mills to convert them to powder form.

Step 2: Sieve the powder form and separate it into the desired grades.

Step 3: Split the powder in 3-micron, 5-micron, 10- micron bags as required.

The important fact is that with 100 tonnes of mine, 99.99 tons is extracted without any further additives.

Calcite Uses

Calcite crystal’s properties make it one of the most widely used minerals. It is used as a building material, abrasive, agricultural soil treatment, construction aggregate, pigment, pharmaceutical, and other applications. It has more applications than nearly any other mineral.

Calcite as Limestone and Marble

Limestone is a sedimentary rock that is primarily composed of calcite. During diagenesis, it is formed by both the chemical precipitation of calcium carbonate and the transformation of shell, coral, faecal, and algal debris into calcite. Limestone is also formed as a deposit in caves as a result of calcium carbonate precipitation.

Marble is a metamorphic rock formed when limestone is heated and pressed. A close examination of a broken piece of marble will usually reveal visible calcite cleavage faces. The degree of metamorphism determines the size of the calcite crystals. Larger calcite crystals are found in marble that has been subjected to higher levels of metamorphism.

Calcite in Construction

The construction industry primarily consumes calcite in the form of limestone and marble. These rocks have been used as dimension stones and in mortar for thousands of years. Many of Egypt’s and Latin America’s pyramids were built with limestone blocks as the primary building material. Today, rough and polished limestone and marble are still popular materials in high-end architecture.

Calcite in limestone and marble are used in modern construction to make cement and concrete. These materials are easily mixed, transported, and placed as a slurry, which hardens into a durable construction material. Concrete is used to construct buildings, highways, bridges, walls, and a variety of other structures.

Calcite Mineral in Acid Neutralization

Calcite has a wide range of applications as an acid neutraliser. Limestones and marbles have been crushed and spread on fields as an acid-neutralising soil treatment for centuries. They are also heated to create lime, which has a much faster reaction rate in the soil.

In the chemical industry, calcite is used as an acid neutraliser. Crushed limestone is dispensed into streams to neutralise their waters in areas where acid mine drainage is a problem.

In medicine, calcium carbonate derived from high-purity limestones or marbles is used. Calcium carbonate is mixed with sugar and flavouring to make chewable tablets that are used to neutralise stomach acids. It is also found in a variety of medications used to treat digestive and other ailments.

Calcium Carbonate Sorbents

Sorbents are substances that can “capture” or “retain” another substance. Limestone is frequently treated and used as a sorbent material in the combustion of fossil fuels. Calcium carbonate reacts with sulphur dioxide and other gases released by combustion, absorbs them, and prevents them from escaping into the atmosphere.

Monuments and Statuary

Marble is a beautiful and easy-to-work-with stone that has long been used for monuments and sculptures. Its lack of significant porosity allows it to withstand freeze-thaw action outdoors, and its low hardness makes it a simple stone to work with. It has been used in projects ranging from the pyramids to a figurine. It is widely used in constructing cemetery markers, statues, mantles, benches, stairways, and other structures.

Many Other Uses

Calcite has a white colour when powdered. Calcite powder is frequently used as a white pigment or “whiting.” Calcite was used in some of the first paints. It is a primary component of whitewash and is used as an inert colouring agent in paint.

Animal feed frequently contains pulverised limestone and marble as a dietary supplement. Cattle that produce milk and chickens that produce eggs require a calcium-rich diet. To increase calcium intake, small amounts of calcium carbonate are frequently added to their feeds.

Calcite Uses in Other Industries

Paper Industry

The calcite is used as filler and coating material in most paper-producing industries to harden or smoothen, as necessary. Calcite allows rapid paper drying in the paper-making process due to its oil absorption feature. This makes it a useful ingredient in newspapers, magazines, and high-quality paper-making factories. Calcite is also used as a filling material for cigarette paper.

Paint Industry

Calcite is used as a pigment material to prevent steel wear, increasing water and chemical resistance.

Tyre Industry

Calcite is the main material used as filler for rubber in tyre-producing factories. With calcite addition, the tyre is usable for a long time without loss of softness which lessens the elongation and stretching.

Plastic Industry

Calcite is also the primary filling material in plastic factories as it helps maintain the thickness everywhere. Also, it provides hardness and flexibility at the same time, along with being resistant to high temperatures.

Agriculture

To obtain larger agro-products from acid-bearing soil types, it is important to supply Ca in increased quantities. This is how life under Earth can be improved, and the pH must be between 6 and 7.5.

Glass-Glass Glue

Calcite increases resistance to chemical effects in glass which is why it is used in glassmaking. It is also used in bottles and window glass making because it brightens the colour of the glass.

The finely ground limestone is used as a filler material in making glass glue due to its oil absorption properties.

Ceramic Industry

Calcite is added to the tile slurry to remove the harmful effects of SiO2 in the medium. It also increases the strength of the ceramic material with its usage by 2-6%. If this percentage is increased, the percentage will change to pink or yellow speckles that will deform at high temperatures.

Water Treatment

Calcite is used to maintain the hardness of the water and can control the watercolour or its cleaning.

Other Sectors

Calcite Distribution Around the World

Calcite is found in almost every continent. There are large hued calcite deposits in Mexico and the USA. The calcite is distributed in the following places as per various nations.

Clay is a fine-grained natural material of soil and contains many clay minerals. The size of the soil particles of clay is usually less than 0.005 mm. There are also rocks that are composed of clay particles. The rock here means a composition of soils, ceramic clays, clay shales, mudstones, glacial clays, and deep-sea clays. Characterised by the presence of clay minerals in varying amounts of organic and detrital materials, such as quartz, the clay geology is formed. The clay geology is also defined by plasticity which is developed when there is a molecular film surrounding the clay particles making it flexible and when in dried form it becomes hard and brittle and non-plastic. Most of the clay is formed as the result of weathering.

Features of Clay Geology

As mentioned above, the defining characteristic of clay is the plasticity when it is wet and the hard nature in dried form. Clay geology shows a huge variety and broad range of water content holding in between the minimum when it moist enough to be moulded and the maximum when the moulded clay is just dry enough for holding on to a shape. For example, the plasticity limit of kaolinite clay, from the kaolinite geology, ranges from about 36% to 40% and the liquid limit ranges between 58% and 72%.

The characteristics of the plasticity of clay geology are attributed to the mineral content such as hydrous aluminium phyllosilicate minerals. There are thin plates formed by interconnecting oxygen and hydroxyl ions which are part of the mineral content. These plates are tough and flexible thus providing the inherent characteristics of the clay. 

The chemistry of the clay minerals and their ability to retain nutritional content such as the cations like potassium and ammonium are important for soil fertility. Some clay minerals are known as the swelling clay minerals as they can take up water to great extent. They increase in volume with the absorption of water and when dried they shrink back to their original volume which can produce cracks and other distinctive textures such as “popcorn” texture in clay deposits. Examples include clay from the smectite geology site and bentonite geology site which is also known as the blue clay. Especially, the clay from the bentonite geology (or blue clay geology) isn’t favourable for civil engineering projects because of this property. 

Varieties of Clay geology

The main kinds of clays are obtained from the kaolinite geology, montmorillonite-smectite geology, illite geology and bentonite geology (or blue clay geology). There are a wide variety of clays, approximately, 30 different types of “pure” clays with a variety of mineral content. But the most naturally available clay deposits consist of the different types of clay along with other weathered minerals. The easiest way to identify clay minerals is X-ray diffraction rather than any other chemical or physical tests. Another kind of clay geology from which a type of clay is obtained is the fire clay geology. The fire clay geology, from which the fire clay is obtained, consists of mineral aggregates of hydrous silicates of aluminium with the presence or absence of free silica. 

Chlorite, vermiculite, talc and pyrophyllite are the types of minerals obtained from metamorphic rocks. The particles of such clay metamorphic rocks are very high in nutritional value and thus provide a significant amount of nutrition nurturing life. Thus, the plant life throws on the mineral content derived from the clay metamorphic rocks.

Concluding with the Importance of Clay

Clay is one of the most important of the various soil components. It has a wide variety of usage and essential material in various industries. As a component of the soil, they are responsible for providing the plants with the environment for growth and by extension nearly all life on the surface of the Earth. Their porous nature aids them in providing aeration, and in water retention. Clay is also a reservoir of nutrient material such as potassium oxide, calcium oxide, and nitrogen as well. 

Furthermore, they are used in pottery. This culture of pottery making surpasses many centuries of human history. Clay pottery also serves as a record of past civilizations. They are used as building materials in bricks either in baked form or even in raw form for ages. Fire clay is another type of clay that is used for the manufacture of ceramics such as fire brick which is used for making furnaces, fireplace, kilns, fireboxes, etc.

Along with bricks clay is also used for making tiles, the cruder types of pottery, as china clay or kaolin for the finer grades of ceramic materials. Another major usage of the china clay is paper coating and filler giving the paper a glossy appearance and increases the opacity of the paper. It is also used in refractory materials including fire brick, chemical ware, and melting pots for glass and also in heat insulators as it increases the resistance to heat. Wool scouring is another example of usage of a certain type of clay known as fuller’s earth. In the process of rubber compounding, the addition of clay increases the resistance for wear and eliminates the moulding troubles. 

Even in engineering, clay materials serve vital purposes. In the construction of the dams, clay provides water impermeability characteristic when added with porous soil. It serves the same purpose of controlling water loss in canals. Along with the limestone, clay either in pure or impure form is utilized as the raw material of portland cement. After treating it with acid, clay can be used as a water softener. Clay also helps in removing calcium and magnesium from the solution and substitutes sodium. One of the other major usages of clay is drilling mud i.e. heavy suspension consisting of chemical additives and weighting materials when employed in rotary drilling.

A continental shelf is the continent feature that is submerged under an area of relatively shallow water this is known as the shelf sea. The shelves are greatly exposed by the drops in the sea level during the glacial periods. The shelf which is being surrounded by an island is known as the insular shelf.

The margin which is located along the continent is situated between the continental shelf and the abyssal plain comprises a steep shaped continental slope which is surrounded by the continental rise, here the sediment from the continent which is above the cascades and down the slope has accumulated a pile of sediment which is at the base of the slope. This extends as far as 500 km (that is 310 mi) from the slope, this consists of the thick sediments which are deposited by the turbidity currents that are originated from the shelf and slope.  

Continental Zone 

Continental shelf or the zone is a broad type, relatively shallow submarine terrace which is made up of continental crust this is formed at the edge of a continental landmass. The geological feature of the continental shelves is very much similar to that of the exposed portion of the continent which is located adjacent to it. Most of the shelves have a gentle rolling topographic feature which is called a ridge. The Continental shelves consist of about 8 percent of the entire area which is covered by oceanic landforms.  

Structure of Continental Zone

A continental shelf extends from the coastal area to the depths of around 100–200 meters (that is approximately 330–660 feet). They are gently inclined towards the sea at an average slope of approximately 0.1°. In all such instances, the shelf ends towards the sea’s edge with an abrupt drop which is called the shelf break.  Below here lies the continental slope which has a steeper zone that merges with the oceanic floor and this is called the continental rise. Here the depth is roughly 4,000 to 5,000 meters (which is moreover 13,000 to 16,500 calculated in feet). 

Few continental margins like that of the Mediterranean coast of France and at the Porcupine Bank, off the western coast of Ireland, do not have a sharp definition of the slope but rather they maintain a generally convex shape structure towards the seafloor.

Widest Continental Shelf 

The widest continental shelf on the planet extends to about 1,210 km (in miles it is 750 miles) it is located off the coast of Siberia, Russia, and into the Arctic Ocean. The Continental shelves serve as an extension of the coastal plains. They are marked by the wide-sloping submerged plains which are approximately 7.4% of the world’s oceanic surface that sits above the continental shelves; they have a global average width of approximately 78 km (that is 48 miles).

The average width of the continental shelf is 65 km (that is 40 miles). Most of the continental shelves are very broad, gently sloping plains which are covered by relatively shallow type water. The water depth which is over the continental shelves is the average that are about 60 meters (which is 200 feet).

Continental Shelf Depth 

A Continental Shelf Depth is about 60 meters. The average width of the continental shelf is around 65 km (that is 40 miles). Most of the continental shelves are very broad and are the gently sloping plains that are covered by relatively shallow water. The water depth is up to 60 meters (200 feet).

200 meters deep is the Continental Shelf of Australia.
This shelf is very shallow, which is up to 200 meters deep, much compared to the thousands of meters deep in the ocean, it extends outward to the continental slope which is quite deeper where the ocean begins.

100m is the continental margin. This is in the Atlantic Ocean, where the continental margins have a shelf that is broad and flat. This reaches a depth of 100 m. Here the slope is the steep transitional area that is between the shelf and the rise, and this lies between the depths of 100 and 2,500 m.

Continental Platform 

In geological meaning, a continental platform is an area that is covered by relatively flat or by gently tilted sedimentary strata. This is an overlie basement that has consolidated igneous or metamorphic rocks which are formed by an earlier deformation. The Platforms, the shield, and the basement rock together make up the cratons. 

Continental Sea 

The Shelf seas or the continental sea refers to the ocean waters which are located on the continental shelf. Their wave motion is controlled by the summation influence of the tides, wind-forcing, and the brackish water which are formed from the river inflows. The regions are biologically highly productive, this is due to the mixing which is caused by the shallower waters and the enhanced current speeds. Despite all covering, only about 8% of the Earth’s ocean surface area, that is the shelf seas supports 15-20% of global primary productivity.

Continental Shelf Location

The Continental Shelf is located at the edge of a continent that lies under an ocean. Here the continents are the main divisions of the land on this Earth. The continental shelf which extends from the coastline of a continent to a drop-off point is called the shelf break. From this break, the shelf descends to the deep ocean floor which is called the continental slope. 

Continental Plain

Continental Plain or the continental margin landform is the broad and gentle pitch of the continental shelf that gives way to the steeper continental slope. Gradual the transition more is the abyssal plain. Here the region is sediment-filled and is called the continental rise. The continental shelf, slope, and rise are collectively known as the continental margin.