August 15, 2013

Reading - 2 Rain Forests

In the scheme of creation, animals and plants have complementary roles. Plants are able to draw nourishment from earth and its minerals. Animals, in turn draw nourishment from plants and from each other. In return, the animals enrich the environment with what the plants need, in the form of carbon dioxide and wastes. Occasionally one of the animals, man, found it necessary to destroy plants; but this was mostly for farming. What happened was that one type of plant was replaced with another. So the harm done was little. On the whole the arrangement was neat. Then came industries.

              Industries need large areas of land just like farming. Unlike in farms where one type of plant is replaced with another, industries destroy plants and replaced them with buildings. Moreover, industries pollute the environment. Waste chemicals from the factories destroy the plants and the carbon dioxide emitted is too much for the trees to cope with. The harm continues as more and plants are destroyed to make way for buildings. As a result the plants are fighting a losing battle.
                   Of special concern are the rainforests. The area of thousands of acres along the equator, throughout the world is the home of the rainforest. It is tightly packed jungle throughout and has been the fortress, since the beginning of time, where a countless of plants and animals have thrived undisturbed. The rainforests are a sort of lung for the world. There are so many plants in the belt that they actually have a great role in the control of world weather. Needless to say, any destruction of the rainforest will play damage with the world weather.

                   In earlier times, the rainforests used to be cleared for farming and a little for timber. But now with the rest of the world’s forest almost used up, the rainforest is being systematically destroyed. What is being used is heavy machinery to destroy vast stretches of the forest at an unbelievable speed.

The destruction is so fast that the jungle cannot recover all. The world is shocked as everyone sees that the harm is to everyone.

The countries which contain the rainforests, there seem to be little alternative. They need the land for farming to support ever increasing populations and the timber from the forest fetches prices in the world market. The other countries that are crying out to save the forests are, ironically enough, those who have already destroyed theirs. The reply of the rainforest countries is a simple one: We are only doing what you have done and for the same reasons as you, to feed ourselves. No one can argue with this.

Can anything be done? One possible answer seems to be that, the whole world can be considered as a single community. If this becomes a reality, then the problem will be resolved immediately. Everyone will be fed from the farms and the industries in places where there is an abundance of land for such purposes. At the same time, the rainforests will belong to everyone and no one will be able to destroy them. Is this a farfetched idea?

        I.            How do animals and plants support each other?
     II.            Why occasional destruction of plants did not cause much damage?
   III.            Write two ways how industries cause extensive damage.
  IV.            Where are the rain forests located?
     V.            What is the ill-effect destroyed the forests at an unbelievable rate with heavy machinery?
  VI.            Why do the countries continue to destroy forests despite the alarm raised by
       environmentalists? Give two reasons
VII.            Suggest a way by which the destruction to the forests can be minimized
VIII.            . Based on what you have read, list four points which prove the importance of the forests.


Reading 1 – The Ring of Fire

Did you know that 90% of the world’s earthquakes and 81% of the world’s largest earthquakes occur along the Ring of Fire? So what on earth is the Ring of Fire? It is a zone of frequent earthquakes and volcanic eruptions that encircle the basin of the Pacific Ocean.

The Ring of fire is 40,000 km long and is shaped like a horse shoe. It is associated with a nearly continuous series of oceanic trenches, island arcs, volcanic mountain ranges, and plate movements.

The Ring of Fire is a direct result of plate tectonics and the movement and collision of crustal plates. The plate tectonic theory explains the forces within the earth that cause earthquakes. Geologists use the term tectonics to describe the deformation of the earth’s crust, the forces producing such deformation, and structural features that result.

The outer layer of the earth, the lithosphere, is broken into about twenty pieces which are known as tectonic plates. These are fitted together like in a jigsaw puzzle. These plates slowly slide around, periodically colliding with each other. Oceanic plates are denser and heavier than continental plates so when the two collide, the oceanic plate slides under the continental plate and is driven into the earth’s interior where it melts to form mountain ranges and volcanoes at the edge of the continental plate; as it is driven upwards a trench forms at the point where the oceanic plate dives under the continental plates.

When two oceanic plates collide one of the two plates sub-ducts (i.e. slides under the other) creating an oceanic trench at the interface. There is tremendous energy created when these plates collide. The subducting plate easily melts as it penetrates the earth’s interior and some of the magma from this rises back to the surface forming volcanic island chains parallel to the oceanic trenches. Volcanoes are temporary features on the earth’s surface. (The world has some 1500 active volcanoes; almost 90% are in the ring of fire; 75% of the world’s dormant volcanoes are also in this region.) The Aleutian Islands of Alaska are an example of this.

When the two continental plates collide one is driven beneath the other. Since both plates are less dense than the oceanic plates they are not sufficiently heavy to sink and melt into the earth’s interior. The crust in the collision area thickens and mountains form. Himalayas in Asia is an example of such mountain.

These plates which are constantly in motion clash into or move away from each other creating stresses and pressure at their margins. These stresses are released through volcanic eruptions when the molten rock is ejected as magma, through fissures in the crust or via earthquakes, then the pressure causes the crust to buckle and move violently. Some scientists say such eruptions help to release pressure and perhaps prevent even bigger explosions happening.


a)      Why is the Ring of Fire called by that name?
b)      What is the Ring of Fire compared to?
c)      What would a tectonics expert be able to explain us?
d)      What are tectonic plates?
e)      Why does the oceanic plate slide under the continental plate?
f)        When they collide with each other?
g)      Where do most number of volcanoes take place?
h)      Mention a place where volcanoes found in past and not at present?
i)        According to the passage how was Himalayas formed?
j)        What is magma?
k)      Name the trench that lies just on the equator.
Based on the information you have decided to make a list of four points that you would present at a discussion ‘The Geographical changes that take place as a result of tectonic movement and collision of crustal plates’.