Showing posts with label Essays. Show all posts
Showing posts with label Essays. Show all posts

09:58

Essay on Waves as agents of Marine erosion

Of all the factors that are capable of shaping a coastline and affecting the coastal geomorphology, waves are the most dominant. At this point it may be pointed out that a detailed description of waves may be found in the third section of the book which deals with 'Oceanography'.
However, it would not be out of place to refer to the two types of wave's i.e. destructive waves and constructive waves. The storm waves fall into the category of destructive waves keeping in view the results produced by them.
In these waves, because of their higher frequency and the vertical plunge of water as they break, the backwash is more powerful than the swash. Such waves tend to move eroded material towards the sea.
The constructive waves, on the contrary, have a more powerful forward push of the swash, and because of frictional retardation, a less powerful backwash.
Such waves instead of moving the material seaward bring it towards the coast. They move water-worn pebbles and cobbles which are coarser than gravels up the sea beach.
It is worthwhile to remember that the average pressure exerted by waves on the coast is about a ton per square foot. During a heavy storm the amount of pressure of the waves may increase threefold.
The storm waves at high tide exert greater effect on the coastline, because their impact is felt higher up the beach or on the seaward face of the cliff.
According to Arthur Holmes, the pressure exerted by Atlantic waves averages over 9700 kg per m2 during winter, while the pressure may still be greater in great storm exceeding even 30,000 kg per m2.
Wave-erosion of the coastal zone is performed in the following ways:
(i) by hydraulic action,
(ii) by corrasive action or abrasion,
(iii) by attrition, and
(iv) by solvent action or solution or corrosion.
The hydraulic action of the wave refers to the force exerted by moving waves on rocks without using its load. Wave erosion of the coastal zone is carried on by the hydraulic action from the sheer physical force of the pounding water and the explosive effect of the air compressed between breaking waves and cliff faces.
Air present in the cracks and crevices in the cliff face is compressed until its pressure is equal to the pressure exerted by the breaking wave. When the wave retreats, the resultant expansion has an explosive effect. This process is repeated with the result that in case of jointed or faulted rock, the fissures get enlarged.
Corrasive action, also called abrasion, plays a very effective role in wave erosion. The corrasive action of sand, gravel and pebbles carried by waves against the shore is the most effective process in marine erosion.
This process is also called 'artillery action' of tools moved against solid rock. The mass of fragments of varying sizes are pounded by the waves against the lower part of the cliff. This undercutting ultimately produces an overhanging cliff. The most striking example of undercutting is provided by caves.
Attrition is another process of wave erosion. When rock fragments are moved by the waves against the cliff, they not only strike against the cliff face, but also dash against each other.
Thus, the fragments during the course of their forward and backward movement by the swash and the backwash are themselves worm down by what is called attrition. In fact, attrition is the mechanism by which the particle size of any material is reduced by friction during transport-in this case by ocean waves.
The sea wave operates as an agent of erosion in another way i.e. by corrosion or the solvent and chemical action. This process is more effective on rocks with calcareous cement or on limestone. Otherwise this process is of limited importance in the case of sea water.

Labels: | 0 comments

09:58

Free essay on The Mechanics of Glacial Erosion

There are two ways in which the glacial erosion is accomplished: (i) by plucking, and (ii) by abrasion. A well-jointed rock is removed by the movement of glaciers. The mechanism of plucking involves vertical pressure by the overlying ice, and downhill drag resulting from flow pressure in the direction of glacier movement.
Stresses are created in the rock whereby existing joints are enlarged. According to W.V. Lewis, pressure-release is the most important way of facilitating the plucking of rocks.
The second method is by abrasion, when the small pieces of rock frozen into the basal ice of the glacier are dragged over the rock floor.
This is how the rock floor is scraped, polished and a notch line is scratched thereon. In doing so the load itself is ground down. Erosion not only produces ground-rocks known as rock flour, but it also produces rock pieces of different shapes and sizes.
Through mechanical abrasion the valley glaciers smooth their floors and walls, thus they reshape the valleys. V-shaped zigzag valleys are converted into U-shaped valleys which are broad and straight. At the base of steep slopes, the glacier produces deep, rather very deep basins. After the ice melts away, these basins become sites of lakes and swamps.
Transportation:
The glaciers are characterized by their tremendous power of carrying the load of different size and shapes. The load is transported on and in the ice.
The valley glaciers derive their load from erosion of the floor and sides of their valleys, and also from the slopes above them. The surface of the glaciers receives different materials brought by avalanches and streams from the mountains sides.
Deposition:
The entire load carried by the moving ice-mass is finally deposited. Such load is a mixture of unsorted coarse and fine debris which is without stratification. This type of glacial deposits is called till.
Rock fragments so deposited are not smooth; rather they are angular and sub-angular because they are carried by the glacier in relatively fixed position.
They are unlike the rounded pebbles and boulders carried by the streams. However, some of the rock fragments are dragged along the valley floor, so they are smoothed and bear marks of striation on one or more sides.
Glacio-fluvial deposits:
The glacio-fluvial transport of material and the related mechanism of erosion and deposition are similar to those of a river when the action occurring belongs to the snout of the glacier.
The glacio-fluvial deposition generally forms extensive outwash plains. It is to be remembered that the melt-water deposits are stratified unlike the deposition made by the ice.
Besides, the debris carried long distances by glacial streams are rounded. In some glaciers there are tunnels beneath the ice formed by running water.

Labels: | 0 comments

09:57

Essay on the Modern Views Regarding the Structure of Atmosphere

On the basis of its chemical composition, the atmosphere is divided into two broad spheres- homosphere and heterosphere.
Homosphere:
This is the lower part of the atmosphere which extends up to a height of about 88 kilometers. It is characterized by uniformity in composition. In other words, the proportions of the component gases of this sphere are uniform at different levels.
In fact, the term 'homosphere' means the zone of homogeneous composition. The homosphere has been subdivided into three sub-layers: (a) troposphere, (b) stratosphere, and (c) mesosphere.
Each sub­layer is separated from the adjoining one by a very shallow transition zone. Tropopause, stratopause and mesopause represent such transition zones.
Heterosphere:
The atmosphere above the homosphere is not uniform in its composition. It has a heterogeneous composition, hence the name 'heterosphere'. Different layers of the atmosphere in this part differ from one another in their chemical and physical properties.
The heterosphere is also referred to as the thermosphere, for in this layer temperature goes on rising up to the outermost boundary of the atmosphere.
It may be remembered that in the upper parts of the atmosphere, where the gases are so rarefied, the high temperatures are caused exclusively by the photochemical actions of the ultraviolet solar radiation.
In this sphere the gases are said to be arranged into the following four roughly spherical shells, each of which has its own distinctive composition: nitrogen layer, oxygen layer, helium layer, and hydrogen layer.
The lowermost layer dominated by molecular nitrogen is called the nitrogen layer. Its average height above the earth's surface is said to be from 88 to 200 kilometers. Above this layer is the oxygen layer consisting of atomic oxygen whose average height above the surface is estimated to be from 200 to 1120 kilometers.
This layer is overlaid by the helium layer which is dominated by helium. It average height above the earth's surface is from 1120 to 3520 kilometers. At the top there is the hydrogen layer extending up to the outermost boundary of our atmosphere.
Its principal component part is hydrogen. The various layers of gases have been found to be arranged in accordance with the weight of different gases.
Nitrogen being the heaviest makes up the lower layer and hydrogen being the lightest is the fourth and the highest layer.

Labels: | 0 comments

09:57

Essay on the concept of motherhood, parenthood and fatherhood

Family is a natural and constant institution in human and social life. Motherhood and fatherhood are, therefore, constants and the family cannot be redefined.
It exists as a norm in all societies except cases which differ from this norm due to widowhood or single parent families as a result of divorce or separation. In fact, motherhood and fatherhood exist as archetypes of human existence with more than mere biological qualities.
There is no recognition of what a mother is, unless one has personal experience of a 'real mother' naturally in relation to her children Similarly fatherhood can be known only through lived experience in a family setting.
Parenthood has a connotation different from motherhood and fatherhood. Human being is the only living creature that is not influenced only by built in natural instinctive mechanism to guide most aspects of one's behaviour.
It goes on learning as it grows and lives as a social being. One has to use relationships with others in order to develop talents, skills and ideas.
This is an essential condition for growth towards personal maturity. Family is the first environment which helps a person to relate oneself to others with natural love and cooperation.
With the entry of a person of the opposite sex in one's life, a new kind of experience and' relationship is developed which finds fulfillment in marriage. Together they learn to leave behind the T and 'you' and think of themselves as 'we', trust understanding grow. They become more open to each other revealing and sharing their inner being, feelings, values and choices.
Every person is meant to be born in a family and called upon to build a new family. Only by accepting family life and its responsibilities seriously a person can learn to reach out to others in love, respect and with a sense of service mentality. The joys and worries of planning, conceiving and bringing up children and social tasks and duties of family compel the couple to forget the self and become more involved with others.
Therefore, we may say that a responsible parenthood is the real parenthood. One has to be responsible to oneself, one's family, spouse, children and the society.

Labels: | 0 comments

19:02

A Hawker

A hawker is a very common figure in Pakistan. He sells his goods from place to place. He does not have a shop. He carries his wares with him and keeps on selling at all places. Hawkers are everywhere. They are to be seen in scores on the streets of Karachi and other large towns. Sometimes they carry their goods in a tray suspended in front of the body and sometimes spread them out on a blanket on the pavement. Another name given to his brotherhood is Cheap Jack for they mostly deal with the cheapest kinds of small articles. Shoe laces collar studs handkerchiefs fountain pens cotton socks and the like. The name was first given in reference to the snatching habits of the hawk, but it is now found in standard ctionaries.
The hawker does not aim a big turn-over or large profits. He wants to make a plain living out of his sales. Since he has no shop he has no rent to pay no rates or taxes in respect of property. None of the things which is the annul balance sheet of a shopkeeper would be entered as expenses. Sometimes his stock in trade is sold stuff which the regular merchant has been unable to sell and so has disposed of to the hawker at a bargain price. He has no reputation to lose, like a merchant who trades in one area and is known to all around, for the hawker is here today and gone tomorrow. He wanders round like a hawk seeking what he can pick up in the way of profit.
The hawker is found all over Western Countries. He will come and knock at your door in an English town. But he fails to compete with the large stores. Formerly he as eagerly waited in country districts, but since communications have improved and shops have been opened even in the small villages the traveling pedlar is becoming thing of the past. In Oliver Twist we read of a man being in prison because he had been hawking saucepeans from door to door without having taken out a liscence, as is required by law.
The regular shopkeeper has a reputation to keep up. It is not in his interests to sell you can inferior article because you will come back and trouble him with your complaints. The hawker has no such considerations to make him do his best for the customers. Tomorrow he may be miles away working in another locality. So it is better to patronize the man who has interests in the social life of the community represented by his shop. Particularly does this apply to ice cream mineral waters and any kind of food or drink. Who knows of what material the ice cream was made or in what insanitary room it ay overnight? Take no risks. The hawker is a picturesque figure with his plausible tongue and strange cries, but he is out for profit at any cost. He leaves no stone unturned to make money and sells goods.

Labels: | 0 comments

19:00

A Pakistani Soldier

Every Pakistani contributes something as for as the defense of Pakistan is concerned. but the role which a soldier plays in defending and protecting the borders of Pakistan is really unparalleled, A soldier is the most disciplined lot of the nation. stability of the nation depends on him.
There is no doubt that a soldiers life is very difficult and hard. It is he who obeys the orders of his commanders and des what is ordered by them. A soldier is the man who keeps night long vigils on the borders in the face of great engrave danger.
A Pakistani soldier is tall, healthy and smart. He is brave and intelligent. He loves his country. He is proud of being a soldier of Islam and Pakistan.
The freedom of a country depends on the courage of its soldiers. A Pakistani soldier is ready to defend his country at all times and in all weathers. He does not know when the enemy will attack. So he has to be always ready and alert.
Only the brave healthy and intelligent men are taken in Pakistan Army. They are given hard and long training. In fact, the training of a soldier never ends. He has to learn the use of weapons and new methods of war. He has to keep himself fit. That is why he is always in military exercises.
Pakistani soldiers are among the best soldiers of the world. In times of war they have done great deeds. They have won many victories.
In the time of peace Pakistani soldiers are not idle. They build roads and bridges in many parts of the country . They help the people when floods earthquakes come.
In the time of war Pakistani soldiers fight bravely but at the same time they help the civilian population. The role which Pakistani soldiers play during indo-pak war is exemplary. Our soldiers helped the civilian population of India. They offered them necessities of life and did not hurt them. Pakistani soldiers acted in accordance with the noble military traditions. We are proud of our soldiers. They do what is expected of them.
A Pakistani soldier is a real hero of the nation and dies for it. He makes history and history makes this name everlasting.

Labels: | 0 comments

18:59

A Good Citizen

A person who is aware of his duties and rights in his society is a good citizen. He knows that he is a member of a group with which he is associated by a thousand and one tries. He realizes that he should live in harmony with other members of society.
Man cannot live without a society . He cannot live alone. He must live with his fellow human beings. But living in a society means co-operation with other members of that society. When you live in a society you have to live as others live. You have to accept the condition and traditions that a society prescribes for its members. These conditions and standards of behaviour are for the common good and welfare of the society and individuals. Society gives you some rights and some duties. A good citizen does his best to do his duty to the society. He always keeps in view the interests of his society and state. He lives a clean and honest life. He keeps away from such activities that may harm the interests of his fellow. A good citizen is aware of the fact that he is indebted to his society in many ways. He knows that the labour and work of countless persons have enriched his life. His life to a very great extent depends of others. He has received much in material and spiritual benefits from others. It is only just and right that he should pay his debts. How does a good citizen pay his debts to society by living a useful and fruitful life? He lives not for himself alone. He lives for others . He pays his taxes. He takes keen interest in the affairs of his state. He does not live in isolation. He is not selfish. He is tolerant kind and virtuous.
A good citizen needs to imbibe many qualities. That he has some duties and responsibilities to bear is true, but at the same time he also enjoys some rights and privileges as a citizen of a free state. While he has every right to participate in the judicial, legal, political, religious and social affairs of the nation, he has also some responsibilities i.e. not to injure the sentiments of others and to protect the weak against the strong. To stand by state under all the conditions is his first and foremost duty.
A good citizen must be ready to sacrifice his everything for the sake of his motherland. He is also required to be a patriot and nationalist. He should have firm and deep faith in the welfare of his motherland. He has to observe law and order. But he has also to keep in his heart the betterment of the country, the welfare of the state, the good of society and the interest of the nation and possess a good moral conduct.
A good citizen must respect the cultural heritage of his country i.e. he will have to respect the heroes, the prophets the sages and saints of his country. He must respect the race which has given him birth. He must always keep in mind the future of his country. He must raise the standard of living of his country by working honestly.
Obedience to laws is the next important public duty of a citizen . Society can make no progress if the people have no respect of laws. If a citizen finds that a particular law is bad he should try to get it replaced by constitutional means. He should not unnecessarily resist a law.
Also at the time of aggression or foreign attacks he must be ready to shed his blood for the sake of his motherland. Thus defense of the country is the supreme duty of a good citizen. He must leave no stone unturned for the prosperity and integrity of his motherland.

Labels: | 0 comments

Subscribe to: Posts (Atom)