Category: Geography Notes PPT

Dolomite is an anhydrous carbonate mineral made up primarily of calcium magnesium carbonate (CaMg(CO₃)₂). A sedimentary carbonate rock consisting primarily of the mineral dolomite is also known as a dolostone rock or dolostone rock type. The word “dolostone” is often used to refer to the dolomitic rock type. Dolomite is a type of limestone in which the mineral dolomite, calcium magnesium carbonate [CaMg(CO₃)₂], dominates the carbonate fraction. Dolomite also exists in an amorphous form, known as dolomite powder.

Carl Linnaeus is credited with being the first to describe the mineral dolomite in 1768. Deodat Gratet de Dolomieu (1750–1801), a French naturalist and geologist, first identified it as a rock in buildings of the old city of Rome in 1791, and later as samples collected in the mountains now known as the Dolomite Alps of northern Italy. After Dolomieu, Nicolas-Theodore de Saussure was the first to name the mineral.

Properties of Dolomite

• The trigonal-rhombohedral system is used to crystallise dolomite. It forms crystals that are white, tan, green, or pink in colour. Dolomite is a double carbonate of calcium and magnesium ions arranged in an alternating structural structure. It does not dissolve or effervesce as quickly as calcite in cold dilute hydrochloric acid unless it is in fine powder form (dolomite powder). Twinning of crystals is very popular. Colourless, translucent, buff-coloured, pinkish, or bluish dolomite crystals. 

• Granular dolomite is a medium to dark grey, brown, or white granular dolomite found in rocks. Dolomite crystals vary in transparency from translucent to transparent, but dolomite grains in rocks are usually translucent or nearly opaque. 

• The lustre varies from dull to subvitreous. Dolomite, like calcite, cleaves into six-sided polyhedrons with diamond-shaped faces. Dolomite and calcite have different relationships between lamellar twinning and cleavage planes, and this distinction can be used to differentiate the two minerals in coarse-grained rocks like marbles. 

• In dolomite and calcite, there are relationships between lamellar twinning and cleavage planes. When thin parts of the minerals are examined under a microscope, this disparity can be seen.

• Some dolostones have granular dolomite, with individual grains varying in size from microscopic to a few millimetres in diameter. The majority of dolomite marbles are coarsely granular, with individual grains varying in size from 2 to 6 millimetres (0.079 to 0.24 inch).

• Dolomite vein grains may be several centimetres in diameter. Dolomite crystals in saddle-shaped clusters, most of which occur on fracture surfaces, range in size from 0.5 to 2 centimetres (0.20 to 0.79 inch) in diameter.

• Dolomite, iron-dominant ankerite, and manganese-dominant kutnohorite form a solid solution. The crystals have a yellow to brown hue due to the small quantities of iron in the structure. Manganese replacements account for up to 3% MnO in the structure. 

• The crystals have a rosy pink colour due to the high manganese content. Magnesium is also replaced in the structure by lead, zinc, and cobalt. Dolomite Mg₃Ca(CO₃)₄ is a mineral that is closely related to huntite Mg₃Ca(CO₃)₄.

Composition of Dolomite

Ferrous iron usually replaces some of the magnesium in dolomite, and a complete sequence between dolomite and ankerite [CaFe(CO₃)₂] is very possible. Manganese may also be used to replace magnesium, but only to a small degree and usually only in conjunction with iron. Barium and lead for calcium, as well as zinc and cobalt for magnesium, are known to substitute within the dolomite structure, though in small quantities.

Dolostones have been found to contain nearly all of the natural elements in trace amounts. However, it is unknown which ones are found in dolomite; others may be found in other mineral constituents of the examined rocks. Just a few of these elements, such as strontium, rubidium, boron, and uranium (U), are known to occur definitively within the dolomite structure.

Dolomite effervesces with dilute hydrochloric acid, but more slowly than calcite; it tends to smoulder slowly in general, and in some cases only after the rock has been powdered or the acid has been warmed, or both. In the field, this variation in the character of effervescence is normally used to differentiate dolomite from calcite. Staining methods, which are often based on chemical properties or standard compositions, may be used in the lab to differentiate between these minerals. The stains commonly used are particularly useful for examining rocks composed of alternate lamellae of dolostone and limestone composition.

Structure of Dolomite

Dolomite is a calcium element or magnesium element carbonate mineral. CaMg(CO₃)₂ is the formula unit composition. The trigonal crystal system of dolomite has a rhombohedral habit. Unlike magnesian calcites, calcium and magnesium are divided into complete separate planes in ideal dolomite. Just a few per cent of calcium is substituted for magnesium in most dolomite samples, and vice versa. 

In a condensed form, the dolomite structure is similar to that of calcite, but magnesium ions replace calcium ions in any other cation layer. As a result, the ideal dolomite structure will include a calcium layer, a carbonate layer, a magnesium layer, another carbonate layer, and so on. The Dolomites, unlike calcites, may exhibit order-disorder relationships, as defined for potassium feldspars. This happens because the purity of some of the cation layers isn’t perfect for example, some calcium layers may contain magnesium, and some magnesium layers may contain calcium. 

The word proto dolomite is also used to describe Holocene dolomites with less-than-ideal dolomite structures. The majority of ancient dolostone dolomites, on the other hand, tend to be well organised. In technical literature, modifications that may represent a variety of calcium-versus-magnesium layering aberrations are discussed extensively.

Distribution of Dolomite

Dolomite is a common mineral found in Spain, the United States, Canada, Switzerland, Austria, and Hungary. When ground, dolomitic limestone (dolostone) can be used as a soil liming material, as well as for building stones and gravel.

Despite the presence of vast deposits of dolomite in the geological record, there is no evidence of dolomite formation under current environmental conditions, such as marine sediments and soils. Dolomite preparation in the laboratory at room temperatures and pressures is still one of the most difficult tasks in mineralogy.

Formation of Dolomite

Modern dolomite formation has been discovered in supersaturated saline lagoons along the Rio de Janeiro coast of Brazil, including Lagoa Vermelha and Brejo do Espinho, under anaerobic conditions. Many people believe that dolomite can only form with the aid of sulfate-reducing bacteria e.g. Desulfovibrio brasiliensis. 

Low-temperature dolomite, on the other hand, can be found in natural habitats that are rich in organic matter and microbial cell surfaces. This happens as a result of carboxyl groups associated with organic matter forming a complex with magnesium. Dolomite is found in large deposits in the geological record, but it is relatively uncommon in modern environments. 

In 1999, the first reproducible inorganic low-temperature syntheses of dolomite and magnesite were reported. During periodic periods of dissolution and reprecipitation, the initial precipitation of a metastable “precursor” (such as magnesium calcite) will eventually change into more and more of the stable phase (such as dolomite or magnesite). Breaking Ostwald’s step rule is the general concept that governs the direction of this irreversible geochemical reaction.

A biogenic occurrence of dolomite has been discovered. The development of dolomite in the urinary bladder of a Dalmatian dog, probably as a result of illness or infection, is one example.

Dolomite Uses

The various type of dolomite uses are discussed below:

• Dolomite is used as an ornamental stone, a concrete aggregate, and a magnesium oxide source, as well as in the Pidgeon magnesium production process. It is a significant petroleum reservoir rock that also serves as the host rock for massive strata-bound MVT ore deposits of base metals including lead, zinc, and copper. Dolomite is often used in place of calcite limestone as a flux for the smelting of iron and steel when calcite limestone is unavailable or too expensive. Therefore, known as dolomite limestone. The processing of float glass necessitates a large amount of refined dolomite.

• Dolomite and dolomitic limestone are used in horticulture as a pH buffer and magnesium source in soils and soilless potting mixes. In marine (saltwater) aquariums, dolomite is used as the base to help buffer changes in the pH of the water.

• Calcined dolomite is also used as a catalyst in the high-temperature gasification of biomass to kill tar. Particle physics researchers want to create particle detectors under layers of dolomite so that they can find as many exotic particles as possible. Dolomite can insulate against cosmic ray interference without contributing to background radiation levels because it contains only trace amounts of radioactive materials.

• Dolomite is highly prized by collectors and museums as it forms huge, translucent crystals, in addition to being an industrial mineral. The specimens found in the Eugui, Esteribar, Navarra (Spain) magnesite quarry are considered among the best in the world. You can easily find the dolomite powder price on the internet.

Did You Know?

• Dolomite can be found in several parts of Europe, Canada, and Africa.

• Rare hot pink dolomite varieties can be found in Africa’s Congo.

• The Dolomite Problem refers to the debate among scientists about the origins of dolomite beds.

• Dolomite does not bubble when exposed to acid, which is a distinguishing feature between dolomite and limestone.

• The Dolomites are an Italian mountain range composed of dolomite rock.

• Dolomite can be used as a calcium or magnesium supplement.

The Indian civilization has always been agrarian. Right from the Vedic Saraswati civilization to the modern times, farmers have cultivated this rich land and cherished their bond with Mother Nature. It is no wonder then that India is a land of abundance and wisdom. 

Agriculture farming in India is a century-old activity, and is currently the highest contributor to the GDP of India. Agriculture remains the largest contributor to the country’s GDP and farmers constitute 58% of India’s population. It means much of India remains untouched by the mindlessness of consumerism. Under its Agriculture Export Policy, the Government of India aims to increase agricultural export by over $60 billion by 2022. This means, the agricultural activity in India will be doubling. If we describe the farmers of India, they constitute 58% of the country’s population. Agriculture is the primary source of income for the mentioned percentage of the population.

The Indian food industry also aims to grow by leaps and bounds.  Already, the Indian food market stands as the 6th-largest globally with food processing covering over 32% of the country’s food industry. Thus, we see that India is enriched by both traditional and commercial forms of agriculture. 

Agricultural Methods of the Indian Farmer

Agriculture farming in India is the oldest activity and has been the major livelihood for farmers. Over the years, farming methods in India have changed, thanks to the technology invention making the lives of farmers easy. Socio-cultural practices, climatic conditions, and other aspects have also contributed to the innovation in Indian farming. Currently, both traditional farming methods in India and modern farming are practiced.

Let us check some of the old and modern farming techniques in India

1. Primitive Farming – One of the oldest techniques in India, primitive farming is practiced in small farms with traditional instruments like a hoe, digging sticks, etc. Farmers depend upon soil fertility, environmental conditions and other factors like heat for the harvest. This method is usually employed by those who use the output for their consumption. This technique is also called “Slash and Burn” farming where farmers burn the land once the crops have been harvested. 

2. Subsistence Farming – Cultivation takes places across wide and larger land areas with two types of crops : wet and dry. Wet crops include paddy and dry crops grown are wheat, maize and pulses. This method demands extensive use of chemical fertilizers and different methods of irrigation.

3. Commercial Farming – This technique is a modern day farming method where the farmers use a variety of new-age tools for surplus profits. Insecticides and fertilizers are also used because the crops grown are spread across large patches of land. It contributes a great percentage to the country’s GDP. While farmers in Haryana, Punjab and West Bengal practice commercial farming techniques, farmers of Orissa continue to prefer subsistence farming for large productions.

4. Plantation Farming – It is another subset of commercial farming. It makes use of both labor and technology to ensure the process is sustainable as plantations are spread across huge patches of land. It includes both agriculture and industry because of the nature of the crops grown. 

Modern Farming Methods in India

Besides the above-mentioned farming techniques in India, there are other methods followed in different regions of the country. Much of these don’t fall under traditional farming methods in India. This includes:

1. Aeroponics System

Aeroponics is the process where plants are grown in the air or mist environment without the use of soil. It is the subset of hydroponics, and suspends the plant root in the air to work. Farmers, by using this method will have better control over the amount of water to use.

2. Aquaponics

Aquaponics is a closed-loop system that relies majorly on the symbiotic relationship between aquaculture and agriculture for fertilization. This farming method combines conventional aquaculture with hydroponics.

3. Hydroponics

The hydroponics method is a less-soil type of farming, and it doesn’t require any type of soil. The process involves growing healthy plants without the inclusion of solid medium using nutrients including water solution which is mineral-rich. Hydroponic farming is the subset of hydroculture, and the nutrients used in hydroponic farming systems have different sources.

4. Monoculture

This method is the raising of a single crop in a specific area of farming. However, in a country like India, the Monoculture technique of farming isn’t widely followed. Indoor farming like growing medicinal plants falls under the monoculture. In plain words, monoculture is a modern agriculture practice where a single crop or plant is grown.

In the lower atmosphere of the earth, particularly in the troposphere zone, we observe the different atmospheric phenomena. The wind is one such element in the earth that controls various changes in the weather phenomenon. To understand the Gale meaning, first, we have to understand that it is also a form of wind. But in Gale, the wind is much stronger than a normal breeze. The wind velocity in the gale is about 50-102 Kilometers and number 7 to number 10 on the Beaufort Scale. A warning about gale is issued by the Weather Service when wind velocity is 34 – 47 Knots or 63 – 87 Kilometers per hour. Gale, meaning in English, is nothing but a strong wind force. We can also call it Fresh Gale.

Gale Company is basically a group that is very much active in doing research. The company used to publish academic, school library, and business magazine and newspaper databases. Gale eBooks’ also cover a wide range of geography topics, including maps, continents, about the people and environment.

To know about the life of David Gale, a popular movie character, we have to go through the movie. David Gale is a professor in Texas, US. He is about to die, and his lawyer explained his life story and secrets. David gale is a famous personality for keeping secrets. Gale is the head of the department at the University of Austin.

Gale and other Wind Force

A famous scientist gives an interesting way to know the relationship between wind direction and horizontal pressure. This famous Dutch scientist in 1857 gave the law Buys Ballot’s law. After doing certain research about the wind, he stated a formula empirically. According to him, a person will experience high wind pressure on the right side and low pressure on the left side when he will stand in the Northern hemisphere, and he will experience the opposite when he is in the Southern hemisphere.

As per this relation, the angle between the wind and the pressure gradient is a right angle. But later, it was revealed that this phenomenon is true in the free atmosphere but not near the ground surface. The angel is always less than 90 near the ground. This is mainly due to the frictional force between the air and the surface and tends to move the air towards the lower atmospheric pressure areas. But this law is not applicable in the equator region because of the weakness of the Coriolis effect, which is mainly formed due to the rotation of the earth.

The name Gale originates from the ancient Norse word Gallin which means mad. But weather forecasts sometimes use this term to signify wind force which is not extreme like hurricanes but a very strong wind force. Gale is also like a bad Tornado because its damage symptom is broad here as it has the ability to uproot shallow-rooted trees. Gale is mainly associated with coastal regions because here, the wind speed is a bit more. The minimum wind speed here is 50 kilometers per hour, and it can extend up to 102 km, so it can be dangerous and have the ability to destroy.

Hail is a kind of solid precipitation, different from ice pellets. It includes balls or irregular lumps of ice, each of which is known as a hailstone. Ice pellets generally fall in cold weather whereas the growth of hail is immensely constrained at cold surface temperature. In contrast to ice pellets, hailstone usually measures between 5 mm (0.2 in) and 15 cm (6 in) in diameter. Hailstone is most commonly found in mid-latitudes and usually lasts around 15 minutes. They generally occur in mid – to -late afternoon. 

Hail is extremely destructive to crops and buildings if large enough, or it may be even dangerous to animals exposed to it.

Hailstorm Definition  

Any thunderstorm through which hail is produced and reaches the ground is known as a hailstorm. Hail has a diameter of 5 mm (0.20 in) or more and can grow to 15 cm (6 in) and weighs more than 0.5 kilograms.

In contrast to ice pellets, a hailstone is stratified and can be irregular and clustered together. Hail consists of transparent ice and alternating layers of transparent and translucent ice at least 1 mm ( 0.039 in) thick, which are laid down upon the hailstone as it travels through the clouds, held off above by air with strong upward motion until its weight exceeds the updraft and falls to the ground. 

The diameter of hail is generally varied, in the United States, the damaged hail, on average, is observed between 2.5 cm (1 in) and golf ball-sized  ( 1.75 in). Stones larger than (0.80 in) are considered to be large enough to cause damage.

Hailstone Formation

Hailstone formation or hail formation occurs when the rain droplets are carried upward through thunderstorm updraft into immensely cold areas and freezes. Hailstones then further grow by hitting liquid water droplets that freeze into the surface of the hailstone. If the water freezes speedily when hitting the hailstone, cloudy ice will form as the air bubbles will be confined in the newly formed ice. However, if the water evaporates slowly, the air droplets will escape and the newly formed ice will be clear. The hails fall when thunderstorm updraft can no longer support thunderstorms weight, which can come about if the stone becomes large enough or the updraft weakens.

Hailstone Meteorology Size

The hailstone size can be best described by measuring the diameter using a ruler. In the absence of a ruler, the hailstone size can be best estimated by comparing its size to that of known objects, known as coins. Comparing the hailstone size using the objects such as eggs, peas, marbles is imprecise due to the varied dimensions. The UK organization, TORRO also measures for both hailstone and hailstorms.

When observing the hail at an airport, METAR code is used within the surface observation which is related to the size of the hailstone. The GR within the metric code is used to represent the larger hail, of a diameter of the latest 0.25 inches (6.4 mm).

The terminal velocity of hail or the speed at which hailstone is falling when striking the ground changes. It is estimated that a hailstone of 1 cm (0.39 inches) in diameter falls at a rate of 9 meters per second (20 mph) while the stone size of 8 cm (3.1 inches) in diameter falls at a rate of 48 meters per e camph. The speed of hailstone cannot be determined accurately as they are not in spheres. 

Did You Know?

• Hailstone can fall at a speed between 9 mph (14 km/hr) and 110 mph (17 km/hr).

• The larger hailstones are faster to fall.

• The hailstorm most commonly occurs in one of the areas of the United States known as the hail alley.

• Hailstorms are formed when thunderstorms carry rain droplets up into the extremely cold areas of the Earth’s atmosphere.

• Approximately 200 to 600 nomads seem to have died of injuries. The haistone of thel size of a cricket ball occurred around the 9th century in Roopkund, Uttarakhand, and India.

Iceberg Meaning: (noun) a Massive Block of Ice That Floats in the Sea.

What is an Iceberg?

Iceberg Definition- Icebergs are a large moving mass of ice chunks that break off from the glaciers. This is known as calving. Icebergs float in the ocean but are composed of frozen freshwater rather than saltwater. Refer to the below image to understand how an iceberg underwater looks like.

Types of Iceberg

To be classified as an iceberg, the ice must be at least 16 feet above sea level, have a thickness of 98-164 feet, and cover an area of at least 5,382 square feet.

Smaller ice chunks are known as “bergy bits” and “growlers.” 

Bergy bits and growlers can come from glaciers or shelf ice, or they can be the result of a large iceberg breaking up. A bergy bit is a medium to large ice fragment. Its height is typically greater than three feet but less than sixteen feet above sea level, and its area is typically between 1,076-3,229 square feet. 

Growlers are smaller ice chunks about the size of a truck or a grand piano. They are about 215 square feet in size and extend less than three feet above the sea surface.

Icebergs are also classified according to their shape, which is typically tabular or non-tabular. Tabular icebergs are distinguished by steep sides and a flat top. non-tabular icebergs have a variety of shapes, including domes and spires.

Are Icebergs Dangerous?

Iceberg underwater is dangerous to ships. The sharp, hidden ice can easily tear a hole in a ship’s bottom. Because of the large number of icebergs that have found their way there, a particularly dangerous section of the North Atlantic has come to be known as Iceberg Alley. Iceberg Alley is located in Canada, 250 miles east and southeast of Newfoundland.

The Titanic, a large British ocean liner on its way to New York in 1912, collided with an iceberg and sank in Iceberg Alley. More than 1500 people perished in the flood. The International Ice Patrol was formed soon after the Titanic sank to track icebergs and warn ships. That patrol is still going on today.

What are Active Safety Measures?

The National Ice Center of the United States monitors icebergs all over the world (NIC). NIC analyses and forecasts ice conditions in the Arctic, Antarctic, Great Lakes, and the Chesapeake Bay. The National Ice Center (NIC) is the only organisation that names and tracks all Antarctic icebergs.

Iceberg patrols now use global positioning system (GPS) technology to help locate icebergs and prevent future disasters like the Titanic. The National Ice Center lost track of an iceberg the size of Rhode Island in 1999. It was discovered drifting toward the Drake Passage, a vital shipping route south of Argentina. Dr David Long of NASA’s SeaWinds science team tracked the iceberg using satellite data, the first time satellite technology was used for that purpose. Since then, the SeaWinds team has tracked the world’s ice using satellites.

Additional Information

The disease pattern in the community or population is described using the analogy of an iceberg. The study of the “iceberg phenomenon of a disease” describes how a disease progresses (pathogenesis and spread) from its subclinical stages to its apparent disease state. The tip of the iceberg represents what clinicians see, while the submerged portion is what epidemiologists explore and make visible. The largely hidden part of the iceberg is what makes up the majority of unrecognised disease in the population and determines the fate of any disease control programme.

• Have you heard of Iceberg Principle? Ernest Hemingway invented the Iceberg principle, also known as the theory of omission, as a writing strategy. Hemingway had to base his newspaper reporting as a young writer on current affairs with no meaning or explanation. He maintained this minimalistic approach as a short story writer, concentrating on surface elements rather than directly addressing overarching concepts. The deeper sense of a plot, according to Hemingway, should not be obvious on the surface but should shine through indirectly. 

The ionosphere and magnetosphere are considered as the regions of the atmosphere of the earth which contains a large number of electrically charged particles. These electrically charged particles are also known as ions and electrons. The radio waves are propagated through these particles as they are large enough. Extraterrestrial radiation that usually comes from the sun creates these charged particles. These are mainly made on the molecules of air and neutral atoms. The Approximate height of the ionosphere is around 50 km that is 30 miles above the surface of the earth.

               

         

Layers of Ionosphere

Traditionally, there are several different layers under the ionosphere. When the discovery of the ionosphere was done, it was found that there were many layers present. The layers were named D, E and F under the ionosphere.

Ionospheric Regions

D, E and F layers are best for structuring out the ionosphere. The level of ionization in the ionosphere changes with altitude. There are peaks in each level of the ionosphere which are called different regions or layers. Along with these regions, there is a C region also under the ionosphere. But the fact is that the ionization level is a bit low as compared to other regions. C region does not affect radio communications and radio signals. There are dissimilar regions under the ionosphere and they have different features and also affect radio signals differently. The ways these regions are created are also different.

D Region

When the surface of the earth is left behind after the skywave and starts moving upwards then the initial region that reaches the ionosphere is known as the D region. D region is present between 60 km to 90 km at altitudes. Several factors are dependent on when there is a loss of signal. The factors are the level of ionisation, frequency of the signal and frequency of the signal.

E Region

E region is considered as a step above the D region. The altitudes of the D region is between 100 km to 250 km. Wherever the existence of the E Region takes place, the air density will be seen less as compared to the D region. The reason why it happens is that the electrons are released out due to vibration and signals and then some of the collisions only occur. Hence the E region is somewhat not similar to other regions.

F Region

Among all the regions in the ionosphere, the F region is considered the most essential region in terms of radio communication. In the presence of the sun, the radiations are being released from the sun and most probably they are divided into two regions. Firstly, the F1 region is considered as the lower one and secondly, the F2 region is a higher one. If the infection point is taken into view then the F1 region will be considered. 

Some Facts about Ionosphere 

• The ionosphere overlaps the top of the atmosphere and the sun cooks gases there until or unless they lose an electron or two that creates a sea of electrically charged particles. Thus, this Ionosphere becomes the shelter to all the charged particles in the Earth’s atmosphere.

• The ionosphere stretches 50 to 400 miles above the earth’s surface and this is just right at the edge of space. Along with this the Ionosphere also forms the boundary between the Earth’s lower atmosphere where we can live and breathe in a proper way. So, the Ionosphere is the part where the earth’s atmosphere meets space.

• The ionosphere is the home to many of our satellites including the international space station. This means these satellites can be affected by the constantly changing conditions in the Ionosphere. This also includes the sudden swells of the charged particles which can increase the drag on satellites and shorten the orbital lifetimes.

• The ionosphere has a great role in everyday communications and navigation systems. For this reason, we are able to get the sound from Radio and GPS signals. In both cases, the Ionosphere’s composition and density can disrupt these signals.

• The ionosphere can be influenced by the weather. Different weathers like thunderstorm systems, hurricanes can create pressure waves that ripple up into the Ionosphere. NASA has done research on this matter and within the past 15 years, NASA satellites revealed the connections between the weather condition changes in Earth’s Ionosphere.

• Besides these, the Ionosphere can be influenced by the space weather and this glows constantly also.