Category Social Sciences

Where do Icebergs go?

            Icebergs are huge masses of ice which have broken away from glaciers in the Arctic and Antarctic regions. They gradually melt away as the upper part is warmed by the sun and the lower part by the warmer waters into which they drift.

            An iceberg may be as much as 250 feet high, although only one­ ninth is above the surface of the sea. It can be a hazard to shipping.

            The worst disaster was to a British passenger liner, the Titanic. This fine ship was thought to be unsinkable, because she had a double skin and 15 watertight compartments. In April, 1912, the liner struck an iceberg in the North Atlantic. Despite her double skin and watertight compartments she was holed and quickly sank. Of the 2,207 people on board, more than 1,500 were drowned.

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Where is surtsey?

            Surtsey is a volcanic island a few miles south-west of the West man Islands which are situated off the south coast of Iceland. The island appeared as a result of a volcanic activity on November 15, 1963. The Icelanders took the infant island into their care because it appeared in their territorial  waters.

            They called the volcanic vent Surtur, and the island Surtsey (island of Surtur): In Old Icelandic mythology Surtur was a giant who brought destructive fire from the south as a weapon in his fight with Frey, the god of fertility.

            During its early life there was doubt about the island’s chance of survival, and many thought it might disappear. A similar one did vanish in 1783 after erupting from sea 65 miles south-west of Reykjavik, the Icelandic capital. Survival and long life were assured when re­peated outpourings of thin flowing lava followed the first violent eruptions. The lava capped the volcano with a gently sloping regular dome which acted as a protective shield.

            The arrival of Surtsey was no real surprise. For the 10,000-mile Mid-Atlantic Ridge, of which Ice­land forms the largest above-sea land mass, had been active along its length for some years up to 1963, although since then things seem to have settled down, al­though further activity is always possible. The neighbouring West man Islands were produced by volcanic activity 8,000 years ago.

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Who first used clocks?

It is believed that the Babylonians fist used a pole fixed in the ground to measure the passing of time. They noticed that the position of the shadow changed during the hours of sunlight. They found that the shadow was long at sunrise and that it slowly grew shorter until it reached a point when it started to lengthen again. They learnt to judge the time by looking at the shadow.

        The simple shadow and pole arrangements were the basis of the various shadow clocks or sundials used by the ancient Egyptians. Eventually sundials were provided with the hour figures engraved on a metal plate.

      The Egyptians also used a clepsydra or water clock. This was a basin-shaped, alabaster vessel filled with water that ran out through a hole in the bottom. The time was indicated by the level of water remaining inside.

      Monks were the first to operate clocks by wheels and weights. Clocks of this type, found in monasteries, date back to the 14th Century. The first spring clock is dated about 1500.

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Why did the continents drift apart?

       One of the most convincing explanations of why the continents drifted apart is that the earth expanded considerably after its creation. This theory can illustrate by imagining the earth as a balloon and the continents as pieces of paper stuck on the outside. As the balloon is blown up the pieces of paper will grow farther apart.

      Other theories suggest that the continents only appeared to drift apart because masses of land were drowned under volcanic waters. But it has been demonstrated that land masses are, in fact, made to drift, by the heat generated from the earth’s interior and from earthquakes.

       Probably a combination of various theories may be necessary to provide a complete explanation.

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What is the Heligoland bight?

        The Heligoland Bight is an arm of the North Sea extending south and east of the red sandstone island of Heligoland. Heligoland is a small remote island of the German north Frisian group lying in the North Sea between the coast of Schleswig-Holstein and the estuaries of the Jade, Weser and Elbe. It is 5,249 feet long and 1,640 feet wide at its broadest point.

          In 1807 Heligoland was a Danish possession but it was seized by the English in 1814 and given to Germany in 1890. Before 1914 Germany developed it as a great naval base with an extensive harbor in the south-east. There was a network of underground fortifications and coastal batteries and it was known as the “Gibraltar of the north Sea”. The Heligoland Bight became famous as the scene of a naval battle between the British and the Germans on August 28th, 1914.

Heligoland became a strong hold again under the Nazis and the capital town of Heligoland was destroyed by Allied bombers. In 1947 the whole character of the island was changed by the destruction of the fortifications.

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Where do earthquakes occur?

      Earthquakes occur mainly in the regions of the earth where mountains are being formed, and where the earth’s crust is under strain.

      Some mountains are formed of great thickness of folded sedimentary rock laid down beneath the sea. Heat currents deep within the earth are thought to suck down sections of the undersea crust and so produce great trenches thousands of feet deep. When the heat currents die away the material forming the bottom of the trench begins to rise because it is lighter in weight. Eventually it is thrust up as a mountain range.

    This is never a smooth process but is accompanied by great friction and heat, as well as by rending and shearing and tearing of deep underground rocks connected with mountain formation cause earthquakes. Even small underground movements may produce violent surface shocks. The great Tokyo earthquake of 1923 which is believed to have killed 25 million people was caused by the twisting of a section of the earth’s crust in Sagami Bay.

     As might be expected, ocean trenches are the seat of a great many earthquakes, for there the earth’s crust is in an unstable sate. Indeed all the deep earthquakes those taking place more than 160 miles below the surface-originate around the Pacific trenches. About 90% of the intermediate earthquake (30 to 160 miles deep) also originates there, as do 40% of the shallow earthquakes (less than 30 miles deep).

      Some shallow and intermediate earthquakes are caused by volcanoes or by a slight shifting of layers of rock at a weak place or “fault” on the earth’s surface. One of the most famous and widely publicized of these is the San Andreas Fault on which San Francisco is built.

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