Category Geography

What is an avalanche?

            An avalanche is a large mass of rock debris, snow, ice or soil that moves rapidly down a mountain slope, sweeping and grinding everything on its path. It takes place when a mass of material overcomes the frictional resistance of the sloping surface. It can be caused by spring rains, dry warm winds or violent vibrations produced by an artillery fire, thunder, man-made blasts or earthquakes. Changes in the depth, pressure and humidity of the snow itself can make one snow layer slide over another and result in an avalanche.

            There have been instances where huge avalanches have blocked rivers and buried towns. They are commonly composed of bed-rock fragments, a few centimeters thick in diameter and include a lot of soil and dust. The rock avalanches are thought to ride on a cushion of compressed air that allows them to travel long distances. A debris avalanche usually occurs in unconsolidated earth materials when weakened by moisture.

            Some snow avalanches occur during heavy snow storms. Sometimes they slide while the snow is still falling, but more often they occur after the snow has accumulated at a given site. One of the causes of snow avalanches is the slow formation of hexagonal cup-like ice crystals under the snow pack. The formation of these crystals creates a zone of weakness near the ground. These crystals act as a lubricant when the upper layers of the snow start sliding down the mountain. The wet avalanche is the most dangerous thing because of its massive weight, heavy texture and tendency to solidify as soon as it stops moving. The dry type is also equally dangerous because it’s entrapping of great quantity of air makes it act like a fluid.

            Sometimes, explosives are used to break large avalanches to control their intensity. Other measures such as snow-fences, wall and snow-bridges are erected on hillsides to check the fury of avalanches.

            Since the avalanches pose considerable threat to the mountain climbers, skiers, and travellers, they are being a subject of a lot of research and study. Geologists and scientists all over the world are working in close cooperation to identify the avalanche-prone areas and to monitor the danger of avalanches. Switzerland has established a Snow and Avalanche Research Institute to locate the avalanche-prone areas. 

What is a rain forest?

          A rain forest is a warm and rainy place with a thick growth of trees. Because of heavy rains, the trees grow tall and close together. The tree tops are so thickly branched that they almost block the passage of the wind. The air is still and uncomfortable. The thick tree top also prevents sunlight from reaching the ground. It is difficult to walk through these areas. Along with a large number of trees, it also has many different kinds of animals. These include noisy birds, hungry crocodiles, lizards, snakes and jaguars. Thousands of insects of different types are also found in the rain forests. There is an ant called ‘army ant’     that eats anything that would not move out of its way. There are certain mosquitoes whose bite is fatal; sweat bees which crawl into people’s ears and noses, and ticks and flies bite their skin.

          Most rain forests are located near the equator. The largest rain forest is the Amazon basin in South America. The temperature ranges from about 20 to 34°C. Thunderstorms occur about every three days. Areas of rain forests experience heavy rains upto 250 cms (100 inches). The tallest trees of rain forest form a covering of leaves called the upper canopy. The upper canopy may be 30 to 46 m above the ground. Smaller trees form lower canopies. The shade from the trees prevents about 99 percent of the sunlight from reaching the ground. Thus there is not much plant life on the forest floor. Dense vegetation close to the ground occurs in clearings and along rivers. These areas are sometimes called jungles.

          There are different kinds of plant and animal life in rain forests. Tropical rain forests contain the greatest variety of wild life including the wealth of insect life. Many of these insects have wonderful forms of camouflage. Also more different species of trees are found in tropical rain forests than in any other kinds of forests in the world. The soil layer in the tropical rain forests is very good for farming. 

Who was Gautama Buddha?

          The word Buddha literally means ‘The Enlightened One’. This was the title given to Siddhartha Gautama. He became the founder of the religion called Buddhism.

          Buddha was born as a prince in the 6th century B.C. in a warrior community of Nepal called ‘Sakyas’. Although brought up in great luxury, he did not show any attachment to the material delights. Even when young, he had a sensitive and philosophical temperament. Though he had everything necessary for worldly pleasures, he was somehow dissatisfied.

          One day Siddhartha went out of his palace grounds on his chariot to get a glimpse of the town. On his way he saw three, sights which he had never seen before: a sick man, an old man and a dead man. These had a deep impact on his mind and made him sad and thoughtful. He could sense the eternal truths of life and realized that life was full of sorrows and suffering. He wondered if sickness, old age and death ultimately grab everyone’s life then what was the goal of life and how men could best use the comparatively short lives they had on this earth. These questions kept on hunting his mind.

          One night Siddhartha left his palace in the pursuit of his goal. He was then 29 years old, married and father to a son. He left behind his wife and infant son in the palace. He spent several years studying under various teachers, but none could impart him the wisdom he was searching for. Finally, travelling from one place to another he reached a place in North India, now called Bodh Gaya. There he sat for many days under a tree in deep meditation, until suddenly one morning he had a wonderful experience of a starting vision of what he had been seeking. The light that shone in him was the enlightenment he was searching for. Buddha delivered his first sermon at Benares on the banks of river Ganges.

          Gautama Buddha died at the age of 80 at Kushinagar, near Benares. After him, his followers were divided into two sects: Mahayana and Hinayana. Buddhism is now followed in Myanmar (Burma), Thailand, Sri Lanka, China, Mongolia, Korea and Japan.

 

Why Egypt is called the Gift of the Nile?

            The river Nile is the longest river of Africa and is considered the life breath of Egypt and Sudan. It is 6648 kms long and runs from the mountains of Tanganayike to the Mediterranean Sea through Africa.

            Egypt is called the Gift of the Nile because its valley is extremely fertile mainly due to the yearly floods and it was this fertility that made its ancient people prosperous and helped them survive calamities. Their ancient religion was based on the Nile, and the lives of the ancient Egyptians center around the river. Here once thrived one of the oldest civilizations in the world going back to more than 5000 years B.C.

            The headwater lakes — Victoria, Albert and Edward, are in the tropical country, south of the equator. Most of the rain there falls during the winter months. The great lakes hold this water and feed it into the Nile gradually during the entire year.

            The Blue Nile and Atbara are the river that mainly cause floods and the humus and mud are distributed by the flood waters along the banks of the lower Nile. So the land there remains a green oasis which would have been a desert otherwise.

            The immense importance of the Nile for Egypt is obvious from the fact that 95% of its population lives along its bank on less than one-thirtieth of Egypt’s land. After the construction of Aswan dam, the Nile serves Egypt in a much bigger way. The dam regulates the flood waters, generates hydroelectric power and irrigates thousands of acres of formerly unproductive land.

            The true source of the Nile is in the mountains of the Congo whence the Kangera flows to Lake Victoria. The river Sebat and others flow into the Nile and increase its volume considerably. From this point onwards it is called the White Nile. The Blue Nile is the longest tributary of the Nile and has its source in Ethiopia like Lake Tana. At Khartoum the Blue and White Nile come together. There are six un-navigable cataracts between this place and the sea. In Sudan the cataracts are used to produce an enormous quantity of electricity. They are circumnavigated by waterways. The two very big dams built on the Nile, and the cataracts supply a large part of Egypt’s electric power. 

Where is the highest railway line in the world?

Railway is one of the most important means of transportation today. Everyday thousands of trains travel on railway tracks throughout the world. While some carry passengers, others carry grain, coal, machinery and many other products. The fastest trains reach a speed of over 200 km/hr.

The highest railway line in the world is in Peru. It is a track on the Morococha branch of the Peruvian State Railways at La Cima at a height of 4,818 m (15,806 ft.) above the sea-level.

The highest railway station in the world is the Condor station in Bolivia at a height of 4, 786 m (15,705 ft.) The world’s longest run railway track is one of 9,438 km (5,864 miles) on the trans-Siberian line from Moscow to Nakhodka, Russia. The highest speed recorded on any National rail system is 515 km per hour by the French high-speed train TGV on 18th May 1990.

 

 

How was the Grand Canyon formed?

The Grand Canyon in Arizona USA is a natural wonder of the world. It is famous around the world for its colourful rocks and majestic spectacle. At certain points, it appears like a magic city of rocks, with temples, towers and castles of dazzling colours all around. Do you know how this great wonder came to be formed?

          The Grand Canyon was formed by erosion of the Colorado River Valley. The mighty force of waters of Colorado River cut out this great gorge in the course of many thousand years. Even now, year by year, the rushing Colorado continues to cut deeper into the bottom of the gorge. This is the deepest gorge anywhere in land.

          The Grand Canyon is about 347.2 kilometres long, upto 20 km. wide and the depth is as much as 2 km at places.

          For years, the Colorado River has slowly cut through the high plateaus of northern Arizona, exposing strata that are millions of years old. These strata are of great interest to geologists because they offer an insight into a long stretch of earth’s history.

          At the bottom of the Canyon, where the Colorado River flows, is an ancient Precambrian rock that contains fossils of primitive algae. The fossils of dinosaurs, elephants, trees and other lives of those times are found in the higher strata. The most recent rocks occur near or at the top of the Canyon. The chains of links of its fossils provide an idea about the evolutionary process.

          Each year, more than 2 million tourists visit the Grand Canyon to wonder at the marvel. In 1919, the United States Government created the Grand Canyon National Park, thus preserving the wealth of the plant and animal life that has become a part of this unique environment.