Characteristics of Sedimentary Rocks

Characteristics of Sedimentary Rocks

Sedimentary rocks are formed by the deposition and solidification of eroded materials of pre-existing rocks by natural agents like river, glacier, and wind at distant places below the river, lake, sea or oceans in layers. As these rocks are formed under water, so they are called Aqueous Rocks.

  1. These rocks are formed of different strata or layers.
  2. These rocks are soft compared to other types of rocks.
  3. As these rocks are not made of crystals, so they are non- crystalline.
  4. Sedimentary rocks contain fossils.
  5. These rocks are porous.
  6. Most of the rocks can be easily eroded.
  7. Rocks which are made of organic remains form the reserves of coal, petroleum and natural gas.

-Rahul Chopra.

Short note on Hirakud Project

Hirakud project is a major multi-purpose river valley porject in India. Hirakud dam has been constructed over the river Mahanadi. The length of the main section is 4.8 km long. The entire Hirakud dam is 25.8 km long.

The construction of Hirakud Dam began in 1948. The dam was started in 1957.

The Hirakud dam irrigates more than 2.5 lakh hectares of land, mainly in Baragarh area.

The water released from Hirakud is utilized in the delta of Mahanadi, by remodeling weirs and Mundali and Birupa Rivers.

The dam also support power stations.

The Hirakud project further helps to control flood control.

-Rahul Chopra.

Brief note on Characteristics of Igneous Rocks

Characteristics of Igneous Rocks

1. Igneous rocks are made of minerals integrated with each other.

2. These rocks are usually crystalline.

3. Igneous Rocks are hard.

4. They do not have layers or strata.

5. They do not contain fossils.

6. Often igneous rocks penetrate into the local rocks.

-Rahul Chopra.

Coal Producing States in India

Coal Producing States in India

The coal producing states (along with the districts) in India are given below:

1. Jharkhand: Dhanbad, Hazaribagh, Bokaro, Palamau, Pakur, Dumka, Deoghar, Daltonganj, Ramgar, Karanpura, Jharia, etc. Jharia of Dhanbad district is famous for high quality bituminous coal. Almost entire cooking coal of India is raised in Jharia.

2. Madhya Pradesh: Mohapani, Pench valley, Bisrampur, Lakhanpur, Jhilimili, Umaria, Sohagpur, etc.

3. Chhatishgarh: Korba, Chirimiri, etc.

4. West Bengal: Raniganj (oldest field, 1774) and Asansol.

5. Andhra Pradesh: Singareni, Tandoor and Kothagudem.

6. Maharashtra: Chandrapur, Wardha, Ballarpur and Kamptee.

7. Orissa: Talcher and Rampur.

8. Uttar Pradesh: Singrauli.

9. Meghalaya: Daranggiri, Chempunji and Langrin.

10. Assam: Makum and Nazira.

11. Arunachal Pradesh: Namchick-Namphuk (Changlang district).

-Rahul Chopra.

Extrusive and Intrusive Igneous Rocks

Extrusive and Intrusive Igneous Rocks

Extrusive Igneous Rock:

When magma gushes out on the earth’s surface, it comes in contact with air and cools and solidifies very fast to form Extrusive Igneous Rocks. They are also called Volcanic Rocks as they come out on the earth’s surface through either volcanic or fissure eruptions. As these rocks cool rapidly they become fine grained and non crystalline, e.g., basalt, rhyolite, andesite. The Deccan Trap in Gujarat and Maharashtra and Rajmahal hills of Jharkhand are made of basalt rocks.

Extrusive rocks are further subdivided into:

  1. Lava Rock: Either through volcanic or fissure eruptions, in the earth’s crust lava comes in contact with air and cools as well as solidifies rapidly. Most of the extrusive rocks are of this type, e.g., basalt.
  2. Pyroclastic Rock: Greek word ‘Pyro’ means ‘fire ‘and `klastos’ means ‘broken pieces’. Solidification of lava, along with the fragments ejected during previous eruption— like ash, cinder and other materials of fiery origin that are blown off from the vent and the crater of the volcano, forms rocks which are called Pyroclastic Rocks, e.g., tuff.

Intrusive Igneous Rocks:

Often magma solidifies at some depth in the earth’s crust to form Intrusive Igneous Rocks.

Intrusive Igneous rocks are further subdivided into:

  1. Plutonic Rocks: These rocks are named after ‘Pluto’, the ancient Roman God of the underworld. These rocks are formed by the solidification of magma at a great depth in the earth’s crust where in the absence of air cooling is very slow. Therefore, large crystals are formed. Hence, Plutonic rocks are also called crystalline rocks. e.g., granite, gabbro. Plenty of granites are found in Chotanagpur plateau of Jharkhand and in Purulia district of West Bengal.
  2. Hypabyssal Rocks: When magma solidifies at shallow depth in the earth’s crust, Hypabyssal Rocks are formed. In the presence of little air, cooling is moderate. So, medium size crystals are formed. Hence, these rocks are also called semi crystalline rocks e.g., dolerite, porphyry. Dolerite is found in the Singbhum district of Jharkhand and in some parts of South India.

– Rahul Chopra.

Sedimentary Rocks and its Classification

Sedimentary Rocks and its Classification

The Latin word `sedere’ means ‘settling down’. Deposition (settling down) of eroded materials of pre-existing rocks by natural agents like river, glacier, wind at distant places below the river, lake, sea or oceans under water in layers and solidification of these sediments (deposited particles) in layers form Sedimentary Rocks. As these rocks are formed under water, so they are called Aqueous Rocks.

Sedimentary Rocks are also called Stratified Rocks (Latin ‘strata’ means ‘layers’) as they are formed in layers. Each layer is called ‘bed’ and the surface separating two adjacent beds is called ‘Bedding Plane’. Cracks developed at angles to this bedding plane due to unequal pressure are called Joints. Remains or impressions of plants and animals embedded in the sedimentary rocks are called Fossils. Fossils are commonly found in these type of rocks. For example, fossils found in the Himalayas, Alps, and the Atlas Mountain in Africa have led the scientists to conclude that all these mountains were formed by sediments

Classification of Sedimentary Rocks

Sedimentary rocks are classified, according to their origin as follows:

1. Mechanically formed sedimentary rocks: When sediments of various sizes are cemented together, this type of sedimentary rock is formed, e.g.,

  • Grit – When small pebbles are cemented.
  • Conglomerate – when rounded and bigger pebbles are cemented.
  • Breccia – When angular fragments are cemented,
  • Mudstone or Shale – When fine particles are cemented.

2. Organically formed sedimentary rocks: When the rocks are formed by the accumulation of decomposed plants or animals, this type of rocks is formed. They are called

  • Calcareous sedimentary rocks, e.g., limestone which are deposits of decomposed shells and skeletons of marine organisms.
  • Carbonaceous sedimentary rocks, e.g., coal which is accumulation of decomposed plants.

3. Chemically formed sedimentary rocks: These rocks are the deposits formed by the precipitation of dissolved salts in water after evaporation, e.g., gypsum and rock salt.

– Rahul Chopra.

Essay on Rising Prices

Rising Prices

Prices of goods have been on a constant rise over past few years. A cursory look at the socio-economic scenario: inflation on a long lease; prices on the run for different consumer articles, purchasing power of money on down-hill slide, a widening budget deficit, strangely enough, consumerism on an ecstatic ascent; foreign exchange reserves at their lowest ebb; strikes and bandhs taking place on every conceivable pretext; and law and order in limbo – the list of ailments could be multiplied to any extent. Ironically enough we are so lost in ‘non-issues’ and overwhelmed by rhetoric and polemics that the malaise around and the malady within have become inescapable and irreversible resultants, the remedy of which seems to lie in the dictum ‘let nature take care of these problems’.

A hard as well as a harsh fact about which there are no two opinions is that the prices of branded consumer products have maintained a steady upward trend regardless of other events taking place in the economy. There has been a steady, upward trend in the prices of major branded consumer food products and toiletries. Barring a few exceptions, the rate of inflation in prices of common articles of consumption’s has kept pace with, or even outstripped the rate of increase in the general price index.

In some areas like milk products and cooking oil, there have been spectacular increases within a span of few months, which have had a considerable impact on consumer behaviour. Prices, which had always been a major factor in influencing consumer-purchase decision, have suddenly assumed critical importance. There is usually a seasonal decline in prices after September because of the arrival of Kharif crop but 1990 has been a special case. Despite a third bumper monsoon in a row, prices have been rising instead of falling since September 1990.

Ordinarily, prices obey the dictates of ‘demand and supply phenomenon’ at a given point of time. But with the explosion of population right at our threshold any talk of curbing or controlling the demand for essentials of life, is like putting the cart before the horse or casting pearls before a swine. Policy makers and planners are fully aware of the catastrophe that an uncontrolled population can cause to the system, however efficient and elegant it may. Mere platitudes and persuasions to put under check this monster have failed to yield results and no amount of mean incentives is going to abate the gravity of situation that stares us in the face.

Besides, the people of the country, as a whole, should be educated and instructed that there are no short cuts to prosperity, although some unscrupulous and unprincipled goons may have acquired wealth and other possessions through dubious means. Nor is the policy of populism an answer to our ever-growing problems. We have seen that under one dispensation ‘loan melas’ are arranged and money distributed for considerations other than economic and equity; under another dispensation loans worth thousands of crores are waived off and thus circulation of unproductive money and budgetary deficits, both of Centre and States, are pushed further in the name of ‘social justice’ ‘egalitarianism’ et al.

Over the years, generation of black-money and the role of ‘parallel economy’ have played havoc with the psyche of common man and thus have distorted and disfigured all talk of ‘socio-economic equality’ and rule of law. With bags full of ‘black-money’ and ‘five-star’ culture the current coin, conspicuous living and open display of ‘money-power’ are but the natural consequences of these distortions.

One can count many other factors that have contributed to the perennial, painful and poignant pressure of prices on a common man’s life, for whom to himself and to his family are becoming an unending nightmare. The cult of consumerism, however fragile, is encompassing more and more votaries in its fold.

A number of factors seem to have propelled a boom in the sale of consumer goods in rural markets. The Green Revolution, along with White Revolution; remittances from abroad of Indians in the Gulf countries; improved literacy and education etc, are creating demands, for goods, the fall-out of which is inevitable on the entire infra-structure of essential and non-essential articles of mass consumption.

Many a time artificial scarcities are created by a quick quirk of circumstances like ‘bandhs, strikes, curfew’, complete or partial break-down of transport net-work due to happenings, agitations, protests in areas of supply of essential commodities like food-grains, edible oils, coal, petroleum products, etc. all these adverse and abnormal causes push the prices further up on the graph and it is a common experience that once the prices have enjoyed the ascent towards sky, they refuse to come down easily and voluntarily, whatever be the intensity of prayers, pleadings or persuasions of ‘powers-that-be’.

For the affluent, the erosion of money-value is the least bothering problem. Business and trading groups feel the pinch for a while and then adjust themselves to the on-going developments by managing the ‘cost and sale’ economics of their respective trades and business. Highly organized sections, whether in public or private sectors, are compensated for any loss of real wages in the form of ‘dearness allowance’, which is periodically revised without much fuss or furry. The vast unorganized man-power, whether in urban or rural areas, as also the daily wage-earners, are left to fend for themselves.

The most surprising of trends is the rise in food-grain prices despite bountiful crops. Related to this is the unreasonable rise in prices after harvesting, the major reason behind these are the now regular increases in procurement prices of food-grains announced by the government. As political stakes have become higher, Governments though most of the eighties resorted to arbitrary increases in purchase prices. While many economists do not dispute the ethics and justification of these hikes, they object to the politics behind them. A stage has now been reached where the market discounts the price rises even before they occur because of their inevitability.

The priced situation is “extremely disturbing” and the current trends indicate that the inflation rate may be a double digit. The hike in oil prices will have cascading effects on all forms of transport and the prices of primary articles carried by it. The Gulf crisis will also make it more difficult to attain the year’s saving target of 21 per cent of GDP. There is a danger of remittances from the region as a whole falling with a dampening effect on achieving the saving target. The health of the economy will depend on the thrust areas – employment and agriculture, being accompanied by fiscal stability, reversing price inflation and correcting the growing pressure on the balance of payments.

Most do not expect any let up in this trend since rising expectations have become inherent in the economic system. For any let up in the price spiral to be possible, the inherent structural deficiencies in the economy and before that, in our life style, thinking, modus operandi and approach to national problems will have to be clearly defined and tackled. Otherwise the housewife’s monthly budget shall remain under heavy pressure, notwithstanding the empty promises of the ‘package of measures’ about to dawn and herald a new eta. While the vaunted ‘Consumer boom’ in the Indian market has not yet lost steam, if the price-line continues its ceaseless climb the future might not prove to be as rosy.

– Bipasha Mukherjee.

Methods of Irrigation in India

Methods of Irrigation in India

A common method of irrigation cannot be followed in all parts of India due to the variation in relief, depths of underground water, soil, temperature, rainfall etc. There are mainly 3 methods of irrigation in India. They are:

  1. Wells and tube-wells.
  2. Tanks, ponds and lakes and
  3. Canal Irrigation.

1. Wells and tube-wells:

38% of irrigation land uses wells and tube wells in India. By this method, wells are dug to reach the underground water level. Then the water is lifted up to the surface to be used for farming. If the underground water level is near the surface, the wells can be shallow. After the wells and tube wells are constructed the water is lifted by two methods:

  1. Common method is the Persian Wheel: Normally animals like cattle drag a rope to the surface at the end of which a bucket of water is lifted from the well to the surface. By the Persian wheel method, a wheel with many buckets around the circumference is pulled by a rope by an animal in such a manner that buckets of water rise from the well to the surface one by one.
  2. The other method of lifting water to the surface used today is by electric pumps or diesel pumps. In a short time large amounts of water can be lifted usually from deep wells or tube wells.

This type of irrigation is common in the plains of North India – Punjab, U.P., Bihar, West Bengal and Assam. Some wells are also seen in Gujarat, Maharashtra, Tamil Nadu etc.

2. Irrigation from tanks, ponds and lakes:

15% of irrigation is provided from tanks, ponds, and lakes. In the plateau of South India impervious rocks do not allow rainwater to penetrate underground. As the relief is undulating rainwater can be easily stored in low-lying area. From such reservoirs of water in tanks, ponds and lakes, water can be used for irrigation by pumping. The main drawback of this method is the loss of water in summer due to high temperatures which does not provide irrigation when required most i.e. dry season.

This type of irrigation is seen in Andhra Pradesh, Karnataka and Tamil Nadu mainly. Such irrigation is also seen in West Bengal, Orissa, Assam, Bihar etc.

3. Canals Irrigation:

Canal Irrigation is the most common method of irrigation providing water to 40% of the irrigated land in India. There are 2 types of canals:

Inundation Canal

inundation canal, which provides water to the fields only during the rainy season or flood times when excess water from the rivers in diverted through inundation canals to the fields. But this canal has less importance since in the dry summer season it cannot provide irrigation.

Inundation Canal Irrigation is common in the deltas of Mahanadi, Krishna Godavari and Kaveri.

Perennial Canal Irrigation

The second type of canal provides water to the fields throughout the year. Only when river have water throughout the year or dams are constructed across them reserving water, then water can be supplied continuously to the fields.

Perennial Canal Irrigation is found in:

  • Uttar Pradesh: Upper Ganga canal, Lower Ganga canal, East Jamuna canal, Agra canal and Sarada canal are all perennial canals,
  • Punjab: West Jamuna canal, Upper Bari Doab canal and Sirhind canal.
  • West Bengal: Midnapur canal, Eden canal, irrigational canals of Damodar, Mayurakshi and Kangsabati projects.
  • Tamil Nadu: Mettur canal and canals of the Kaveri delta.
  • Kerala: Malampuzha canal and Pamba canal.
  • Andhra Pradesh: Godavari delta canal and Krishna delta canal etc.

By Amit Agarwal

Bhakra Nangal Dam Multipurpose Project

Bhakra Nangal Dam Multipurpose Project

The Bhakra Nangal Dam is the largest river valley project in India. It has been implemented by the joint efforts of the Punjab and Rajasthan Governments.

The plan for Bhakra Nangal Dam was accepted in 1948 and work began in 1951. Under this project, a 226 meters high dam was constructed across river Sutlej, tributary of the Indus, at Bhakra in Himachal Pradesh. To the south of it, 13 km away at Nangal in Himachal Pradesh, another 29 meters high dam was constructed.

From these dams nearly 1104 km long main canal and 3360 km long branch canals were constructed providing irrigation to nearly 14 lakhs hectares of land in Punjab, Haryana and Rajasthan. Under this project, 4 hydel power stations have also been set up at Bhakra, Gangwal and Kotla (Production capacity approximately 1204 megawatts).

By Amit Agarwal

Iron-Ore in India

Iron-Ore in India

Iron & Steel are extracted from iron-ore. Iron-ore has many impurities when extracted from the mines so it has to be smelted. After smelting, the impurities are removed and the iron rich material is again smelt and into it is added the required amounts of manganese, nickel, chromium, etc to produce steel. Both steel and pig iron are produced from it.

Uses:

Iron is very strong and tough. At present it is the most widely used metal. Steel is used to produce needles or pins, railway tracks, bridges, wagons, coaches, trucks, buses, motor vehicles, machines, furniture, utensils etc. Thus, an iron and steel forms the backbone of the modern age and it has been seen that the more a country produces the more economically developed it is.

Classification of iron-ore:

According to the content of iron in the rocks, there are mainly four types of iron-ore:

  1. Magnetite is best quality iron-ore with 72% iron content and black in colour.
  2. Hematite is reddish in colour and has 70% of iron content or less.
  3. Limonite is brownish yellow in colour with nearly 60% of iron.
  4. Siderite is grayish brown in colour with low iron content, nearly 48%.

Magnetite and Hematite are good quality iron-ore and used widely in iron and steel industries of the world. Limonite and Siderite are low grade iron-ore which are seldom used commercially in the world. In India, most iron-ore is of Hematite. Magnetite ore is mined from Kudremukh region of Karnataka and a few other areas in India.

Producing Areas:

In India most of the iron-ore is produced from the ancient rocks of peninsular India.

  1. Chhattisgarh – Produces 25% of the total iron-ore production in India and ranks first. Mines are located in Durg and Bastar district.
  2. Goa – Ranks second in production of iron-ore.
  3. Karnataka – It is the third largest iron-ore producing state in India. Important mines are Donai-Malai in Bellary-Hospet region, Debadri, Bababudan in Chikmagalur district, Kudremukh in Chitradurg district and Arasul in Shimoga district.
  4. Jharkhand – Ranks fourth in India. The Iron ore producing areas are Noamundi (some areas located in Orissa), Goa, Budaburu, Singbhum district. Recently at Chiria in this district probably the world’s largest deposit of iron-ore (nearly 200 crores tones) has been discovered.
  5. Orissa – Ranks fifth in India. The areas of production of iron ore are Gorumahisani, Sulaipat and Badampahar in Mayurbhanj district, Kiriburu and Bagiaburu in Keonjhar district and Bonai in Sundargarh district.
  6. Andhra Pradesh – Cuddapah, Kurnool, Nellore, Anantapur, Khammam, etc.
  7. Tamil Nadu – Salem, Tiruchchirappalli, Madurai, Tirunelveli etc.
  8. Maharashtra – Chanda, Ratnagiri etc.
  9. Rajasthan – Jaipur and Alwar.
  10. Haryana – Mahendragarh.
  11. Himachal Pradesh – Kangra Valley.

Iron-ore Reserves:

Surveys conducted by Geological Survey of India and Indian Bureau of Mines has indicated that India has a total iron-ore deposit of nearly 1346 crores tons. The reserves of Hematite is 1005 crores tones and the magnetite variety is 341 crores tones. Hematite is mainly found in Jharkhand, Orissa, Chhattisgarh, Maharashtra, Goa and Karnataka. Deposits of magnetite occur along the west coast of Karnataka, Kerala, Tamil Nadu and part of Andhra Pradesh.

Iron-ore Production:

India ranks fifth in the world in iron-ore production after China, Brazil, Australia and Russia. The iron-ore mines in India have an annual production capacity of nearly 8 crores tones. In 1950-51, only 50 lakhs tones of iron-ore was produced. In 1999-2000 nearly 7 cores 35 lakhs tones of iron ore were produced valued at Rs. 1965 crores.

Nearly 50% of the iron ore produced in the country is exported to Japan, South Korea, Italy, Iran, Poland, Hungary etc.

By Amit Agarwal