B u B b L e L i N k Z

Why is it possible to estimate the age of fossils?

2012-02-14T12:36:00.000-08:00

Age of fossils - it is possible to estimate the relative age of fossils, that is weather they came before or after a particular period, because most fossils are found in sedimentary rocks. These are rocks made of sediment which has been compressed or cemented together in layers. Older rock layers, or strata, are usually at the bottom. So each layer is younger than the layer below it an older than the one above. Fossils may be present in igneous rock (hardened the volcanic lavas)and metamorphic rocks (formed by pressure and heat within the earth) but they are usually destroyed. Telling the age of fossils in terms of years, or absolute time, is a much bigger problem. But scientists use several methods. The tree ring method, counting annual growth rings, can give a scientist a reasonably accurate date back to about 3,000 years ago. The varve method, based on counting the annual layers of sand and clay deposited in a lake, bay or river by melting glaciers, can be used for deposits less than about 15,000 years old. Similar calculations based on the rate of sedimentation, erosion, salt accumulation etc. have been successfully applied to very much older rocks. The third method is concerned with radioactive decomposition and is based on actual changes in some of the rock elements or in the fossils themselves. Radioactive uranium gradually changes to uranium lead, radiocarbon to nitrogen and so on. From proportion of uranium lead to uranium in the rock we can date the oldest rocks and fossils, nearly 3,000 million years old.

Why does the Mediterranean Sea look blue and the Atlantic Ocean look green?

2012-02-10T10:52:00.002-08:00

Mediterranean - the blueness of the Mediterranean and the greenness of the Atlantic Ocean are mainly due to the different amounts of sunlight reaching the water's surface. Owing to their different geographic positions, the Mediterranean is far more often directly exposed to sunlight than the Atlantic. The blue colour of the sea is the result of the molecules of light scattering in the water. The green colour of the Atlantic comes from decayed plants on the ocean bed. When these aquatic plants decompose, yellow pigments are released. It is this yellow, mixed with the already murky blue of the Atlantic that creates the characteristic green colour of that ocean.

Where is the Gulf Stream?

2012-01-26T08:35:00.000-08:00

Gulf Stream - is in the Atlantic. It is a warm ocean current which flows steadily from the Gulf of Mexico north-eastwards. One branch reaches the Canary Islands, turns southwards and moves back across the South Atlantic. The other branch flows past the western coasts of northern Europe. This current, which is like a river in the sea, is 50 miles wide at its narrowest and nearly 2,000 feet deep. It sweeps along with it many forms of war water life from the tropics, but these die before they reach the European coasts where the warm water mixes with cold water moving down from the Arctic. The Gulf Stream has a great effect on the weather of Britain and Norway. The prevailing south-westerly winds are warmed by it and collect moisture which turns into rain. In winter the warm water keeps open the cold northern ports, such as Hammerfest, in Norway, and Murmansk, in the Soviet Union, while harbours in the Baltic, many miles farther south, are blocked with ice. In summer it causes bright flowers to bloom on the west coast of Spitzbergen 500 miles north of Norway. In contrast, the east coasts, cooled by Arctic water, is bleak and colourless. In 1912 the United States Congress was asked for money to build a jetty which, it was thought, would divert the Gulf Stream and make it flow up the east coast of the United States. Although this scheme was unlikely to be successful, it was just as well for Britain and Norway that it was never tried. Without the Gulf Stream, Britain's winters would be very much longer and colder, and Norway's harbours, which are vital to the country, would be frozen over for many months.

Where is the mistral?

2012-01-17T23:45:00.000-08:00

Mistral - this is the name given to a wind which blows in the Rhône Valley in France. The wind is caused by an exchange of air between the cold hinterland of France's Central Plateau and the warm Gulf of the Lion in the Mediterranean Sea. High mountain ranges near flat country produce unpleasant winds, especially where the mountains descend to a warm sea. Atmospheric pressure is high above the cold mountains, but low above the sea. Air, therefore, flows towards the sea and is not warmed because it has not crossed enough land. The north-westerly mistral, funnelling down the constriction of the Rhône Valley, blows at a speed of 30 to 60 m.p.h. on at least 50 days each year. It bursts out on to the Mediterranean coast, filling holidaymaker's caravans with sand and capsizing yachts caught unaware at sea.

Where is the "Moho" - Mohorovicic discontinuity?

2012-01-01T10:02:00.000-08:00

The Moho - the Mohorovicic discontinuity is to be found between the earth's crust and the earth's mantle. Mohorovicic was a famous Croatian scientist, a seismologist. He specialized in the composition of the earth, and particularly in earthquakes and in faults in the structure of the earth, which are the cause of earthquakes. Mohorovicic made a most important discovery. Scientists knew that the earth is made up of a series of layers, rather like an onion. There are many of these layers, all of different materials and all in a different state of development. The main layers are called the crust, the mantle, the liquid core and the solid core. The great pressures inside the earth force the weaker areas of the rocky layers out of alignment and this pushing, twisting movement is experienced as an earthquake on the surface. These great forces set up in series of waves throughout the various layers of the earth, known as seismic waves. Mohorovicic discovered a curious fact about the behaviour of these earth waves or tremors. He noticed that the shock waves travel comparatively slowly through the actual crust of the earth. But when they reach the lowest level of the crust-the layer called basaltic rock which rests on the next layer called the mantle - the waves increase dramatically in speed. Sometimes they also change direction. This curious fact was proved of Mohorovicic's experiments. The importance of his discovery was that it proved the earth's crust is different from the mantle beneath. So the "Mohorovicic discontinuity" is the scientific term used to describe this strange behaviour of the earth's shock waves. Usually this level of the earth's composition is called the Moho, since even scientists found Mohorovicic's name difficult to pronounce ! By plotting these earth waves on sensitive shock recording machines known as seismographs we have found that most of the outer crust of the earth is between 20 and 25 miles thick in continental areas, but only three miles thick under some oceans.

When does a geyser erupt?

2011-12-29T09:03:00.000-08:00

Geyser - occurs when a hot spring erupts, hurling a column of water and steam high into the air. These springs are situated in regions which were formerly volcanic and which have retained considerable heat near the surface. They usually have craters with well-like shafts penetrating into the earth. The water which gathers deep down in these shafts becomes heated until the lower part is changed into steam. The pressure of the steam steadily mounts to a point when it suddenly hurls the water above it into the air, sometimes to a height of over 100 feet. The chief geyser districts are in Iceland (home of the Great Geyser), in the Yellowstone National Park, Wyoming, United States, and in New Zealand. For four years Waimangu in New Zealand, the greatest of all geysers, was capable of spouting jets up to 1,500 feet.

When will the world's supply of oil run out?

2011-12-29T08:55:00.000-08:00

World's Oil - Many experts believe that the world's oil supply may run out by the end of the century unless vast new oil fields are discovered. At the end of 1969 the total known reserves of crude oil were calculated at more than 500,000 million barrels, or 21,000,000 million gallons. At the present consumption rate of 50 million barrels a day, this supply would run out in around 30 years from now. However, it has been estimated that consumption will be more than 80 million barrels a day by 1980 and more than 120 million barrels a day by the year 2000. But by then more efficient methods may have been invented for getting the maximum amount of oil out of the ground. Also, extensive new deposits may have been found, possibly in Antarctica or under the sea, on a much bigger scale than the discoveries off the coasts of Britain and northern Europe. The possibilities of producing oil from shale on a commercial scale are now being investigated in the United States.

When does an underground river form?

2011-12-13T10:56:00.000-08:00

Underground River - is formed when the top soil of the land makes it extremely easy for water to pass through to a more solid soil structure. Another kind of underground river is created when a powerful spring in a mountain has to find a channel to the surface owing to the solidity and compactness of the rocks. Finally, an underground river may form as an effluent to a larger river above ground, if there are faults in the surrounding land. Some rivers travel underground only for a part of the journey, such as the Rhône in France.

An underground river at Wookey Hole, in Somerset, England.

Where do countries get their names from?

2011-12-10T08:28:00.000-08:00

Naming The Nations - countries do not all have universally accepted names. Holland is officially The Netherlands. Finland is called Suomi by its own people. The names of countries often spring from the discoverer and sometimes from a native tribe or even a conquering people. America is named after Amerigo Vespucci, the explorer, France after the Frankish invaders, and England after the Angles. The Greeks and Romans called England "Albion" - which is probably derived from albus meaning white and is a reference to her white cliffs-the first things the Romans would have seen on their arrival. Spain in Spanish is España and in Latin, Hispania. An amusing story of the origin of Quebec in Canada is that it was so called because the French sailors who first saw the rocky promontory cried: "Quel bec !" or "What a beak !"

Where is the world's highest waterfall?

2011-12-10T07:35:00.000-08:00

Highest Waterfall - is in Valenzuela, South America. It is known as the Angel Falls and lies on the River Carrao. This magnificent waterfall tumbles 3,212 feet down to the river. The Venezuelans did not even known about Angel Falls or the surrounding country until the 1930's, because steep rocks made overland travel to the region impossible. It was not until aircraft started penetrating the region that the falls were discovered. The falls get their name from the United States adventurer and explorer James Angel who crashed near them in an aeroplane in 1935.

Where does sulphur come from?

2011-12-03T20:18:00.000-08:00

Origin of Sulphur - is a volcanic product. It has many industrial uses. The volcanoes of Sicily and Japan were once the world's chief suppliers. Today important sources are in Texas and Louisiana in the United States. In the coastal regions there are underground sulphur domes. Two pipes, one inside the other, are forced down to the domes. Superheated steam is pumped down one of the pipes, melting the sulphur which is then forced up the other pipe. This method provides 92 per cent of the United States output. The other source is from sulphides of various metals which are called "pyrites". It is the main source of sulphur in Sicily and Japan today.

Where are the Pillars of Hercules?

2011-11-20T21:03:00.000-08:00

Pillars of Hercules - are on either side of the Strait of Gibraltar. The legendary Greek hero Hercules was said to have erected the Pillars on a journey to capture the Oxen of Geryon, a monster with three heads who lived on an Atlantic island. Passing out of the Mediterranean he threw up the rocks on either side of the Strait of Gibraltar. They were the Rock of Gibraltar and the headland on the Moroccan side. Hercules' journey was one of the 12 labours that the son of Zeus had been set by Eurystheus, King of Tiryns, whose servant he had become. One of the most famous of these labours was the cleansing of the Augean stables. So innumerable were the herds of cattle that used these stables that, as they returned from pasture, they seemed to reach endlessly across the plain. Their stables were heaped high with manure and had not been cleaned for years. Hercules diverted the Rivers Alpheus and Pereus through them, and completed the task in one day. For his last labour he braved the Underworld to capture Cerberus, its three-headed watchdog.

What is a National Park?

2011-11-14T06:09:00.000-08:00

National Park - is an area where natural scenery and wildlife is protected by law to preserve them for future generations. It is only recently that man has realized that he must make a possible effort if many species of wildlife and areas of great beauty are not to disappear for ever. There are many kinds of areas of conversation and their central priorities may differ slightly. In the U.S.A., a national park such as Yellowstone safeguards natural features and wildlife in a way that will contribute to public enjoyment. In Africa generally, as in the Amboseli Game Reserve, the chief purpose is the preservation of the remnants of the great herds of animals which once roamed the country. National Parks depend on tourists for revenue but the animals must remain unmolested. To solve the problem many parks restrict visitor's movements by setting aside areas for hotels, restaurants and parking places and providing a limited number of roads through the park. National Parks may be small or large, privately or government owned.

What is dew?

2011-11-09T09:58:00.000-08:00

Dew - is the result of condensation on the surface of the earth. At night the earth sometimes becomes colder than the air, and when water vapour in the air touches leaves and other objects on the earth's cold surface in the early hours of the morning, it condenses to form "dewfall". If the earth is very cold the vapour freezes and hoar frost, instead of dew, is formed. If, on the other hand, water vapour rising from the earth meets a leaf colder than itself, it will condense to form a different kind of dewfall.

What is the Date Line?

2011-11-09T09:44:00.000-08:00

Date Line - usually called the International Date Line, is a north-south line through the Pacific Ocean where, according to international agreement, the date changes. East of the line it is one day earlier than it is to the west. The line is necessary because the earth is divided, longitudinally, into 24 one-hour time zone (15 degrees longitude each) which make one full day on the earth. Since the earth rotates eastwards, the time of the clock progresses westward round the world. Thus, 12 o'clock noon arrives in London (0 degrees longitude) five hours before it does it Washington, D.C. (75 degrees west of London) and eight hours before it does at San Francisco (120 degrees west of London). When it is noon in London it is midnight 180 degrees to the west. On either side of the 180th meridian the time is the same. But you would lose a day if you crossed it from the east and gain one if you travelled from the west. The Date Line has some variations from the 180th meridian to allow for land areas or islands. The line bulges eastward through Bering Strait to take in eastern Siberia and then westward to include the Aleutian Islands with Alaska. South of the equator it bulges east again to allow various island groups to have the same day as New Zealand.

What is the Heligoland Bight?

2011-11-06T07:09:00.000-08:00

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 harbour 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.

Where was the greatest volcanic eruption?

2011-11-04T01:33:00.000-07:00

Volcanic Eruption - the greatest volcanic eruption, in modern times, was on an island in the Sundra Strait between Sumatra and Java. On August 27, 1883, the volcano of Krakatoa suddenly erupted with a tremendous explosion that has been estimated to be the equivalent of 26 large atomic bombs. Rocks and ash were hurled up to 12 miles in the air and over half of the island was blown away. More than 160 villages was destroyed and 36,000 people were killed by 120-foot-high waves which were caused by the explosion. The sound of the eruption was clearly heard four hours later nearly 3,000 miles away. Dust and ashes fell, days later, on Singapore and southern Java. Clouds of volcanic dust thrown high into the atmosphere travelled round the world and caused spectacular sunsets, even as far away as western Europe. In the eruptions, which lasted two days, the highest part of the island became a huge crater which was filled by the sea. The remaining part was covered with layers of lava and ash which stayed hot for weeks. No life was left on the island. But a small monkey was rescued from a floating piece of wood in the Sundra Strait. She was badly burned, but had survived one of the worst volcanic disaster ever recorded in history.

What makes rain?

2011-11-04T01:30:00.000-07:00

Rain - comes from water which has evaporated from the surface of seas and lake. If this water vapour hits a cold patch it condenses or turns into cloud. As long as the cloud meets only air of the same temperature it will go on holding its moisture without bursting. If the cloud meets warm air and is not too dense, it may evaporate again and disperse, leaving a clear sky. But if the cloud meets cold air it will turn back into water and fall to the ground as rain. If the air on the way down is freezing, the rain may become snow before it reaches the ground.

Where is the oldest republic?

2011-10-31T11:10:00.000-07:00

Oldest Republic - the tiny country in San Marino, a few miles from Rimini on the Adriatic coast and surrounded by Italy, set up its own government in the 10th Century. This makes San Marino the oldest surviving republic in the world. According to the legend it was founded in the 4th Century in Marinus, a stone cutter in Dalmatia (now part in Yugoslavia). He fled to a mountain retreat, Monte Titano, to escape persecution by the Roman Emperor Diocletian. Marinus bequeathed this retreat to his followers to remain evermore as an island of liberty in a tyrannical world. The republic's capital, San Marino, is built around the three craggy tops of Monte Titano, which rises to a height of 2,425 feet almost in the centre of the country's 24 square miles. Over the centuries the republic has been invaded several times but has always regained its independence. In 1861, the people in San Marino, considerate of others, wrote of Abraham Lincoln expressing their concern over the troubles in America. An appreciative Lincoln wrote back: "Although your dominion is small, your state is nevertheless one of the most honoured in history". Napoleon had offered this "model of a republic" additional territory in 1797, but San Marino declined to accept it. The inhabitants are of Italian origin but they have one big problem. Over the centuries the families of the republic became so inter-related that the citizen found it impossible to provide a completely impartial system of law enforcement. Because of this they decided to "import" their judge and police forces from Italy. In this way the San Marino families have avoided feuds and family charges of favouritism.

Why do we study ecology?

2011-10-30T01:37:00.001-07:00

Ecology - is concerned with the relationship between living things and their environment. This leads directly to the conservation of natural resources which is one of the most important problems facing the world today. Plants, animals and men are so closely associated and dependent upon each other ecologist's range of study is world-wide, although each special field has its own techniques. The world ecology is derived from the Greek oikos, meaning house. Branches of ecology include types of environment, relationships between certain organisms and plants, game conservation, overcultivation, overpopulation and hundreds of others. Most field of study are inextricably bound up with the destiny of man. As it is such an enormous subject there is a danger that the information obtained will not be available soon enough to ensure proper conservation.

Why do clouds have different shapes?

2011-10-30T01:37:00.000-07:00

Shapes of Clouds - vary in shape according to their height and temperature, and they contain minute drops of water or ice particles or a combination of both. And, of course, their formation is greatly affected by wind changes. There are basically three groups of clouds: high clouds between 17,000 and 45,000 feet (cirrus, cirro-cumulus and cirro-stratus); middle clouds between 7,000 and 23,000 feet (alto-cumulus, alto-stratus and nimbo-stratus); and low clouds up to 7,000 feet (strato-cumulus, stratus, cumulus and comulo-nimbus. Their height and temperature decide how much pressure is exerted on them by the atmosphere. Finally, the shapes of clouds differ according to the time of day. Towards evening clouds tend to thin out, rise a little and flatten out.

Why does Ayer's Rock change colour?

2011-10-26T09:06:00.000-07:00

Ayer's Rock - the colour of Ayer's Rock alter continually according to the atmospheric conditions and the changing angle of the sun. The rock is an immense sandstone boulder rising 1,143 feet out of the flatness of the plain near the centre of Australia. It is normally red, and measures over five miles round the base with relatively gentle slopes which can be easily scaled. The most dramatic effects occur at sunrise, when the sun's rays inflame the rock to a burning crimson, and at sunset, when marvellous purple shadows overlay the glowing blood-red monolith. The colours of the rock vary from a yellowishochre through all the various shades of oranges and reds to a deep purple and to black. Ayer's rock is now one of Australia's most popular tourist attractions, though visitors of one kind or another have been travelling far for centuries to see the massive shape. There was a time when it was regarded with great awe as a religious shine. People from the local tribes came to the caves around its base to worship and to decorate the walls with paintings. The rock was discovered by an Englishman, W.G. Gosse, in 1873 and named after Sir Henry Ayers, then Prime Minister of South Australia. The spot was so remote and inaccessible that for years few people ever visited a rock. Now they come by car and airplane and the rock forms part of the Ayer's Rock-Mount Olga National Park, 487 square miles in area, where the local plant and animal life is strictly protected. Desert oak, mulga, mallee, bloodwood and spinifex are some of the erotic names of plants that grow here. No less strange are the names and appearance of the animals-kangaroo, wallaby, bandicoot and euros.

Where is Tristan da Cunha?

2011-10-19T12:14:00.000-07:00

Tristan da Cunha - is one of five small and remote islands in the South Atlantic midway between Buenos Aires in Argentina and the Cape in Good Hope, South Africa. Tristan is the only one of the five to be inhabited. The island is 37 square miles in extent and was named after the Portuguese admiral who discovered it in 1506. Tristan da Cunha was created in prehistoric times when a volcanic eruption raised it 18,000 feet from the seabed. Cultivation is possible only on one part of the rocky outcrop, on a small plateau squeezed between the sea in one side and 2,000 foot cliffs on the other. In 1816 Britain landed a small force of men on the island and took possession. The garrison stayed for a year. When it departed, one of its members, Corporal William Glass, was allowed to remain on Tristan with his family. With the arrival of shipwrecked sailors and of five women from St. Helena, the population grew to 260 by 1961. For 150 years the islanders way of life changed little. But in 1961 the volcano erupted and forced their departure to England. This evacuation seemed to be the end of life on Tristan but, weary of contact with modern civilization and longing for their island ways, the people began to return two years later. the Tristan da Cunha Development Company now provides the island's sole industry. By 1967 Tristan had a small harbour for the first time in its history. After that a road, a new hospital and a sewage system were built, and electricity was introduced. The island now has something approaching the best of both world, isolation and "away from it all" atmosphere but some modern amenities, too.

Where is Oberammegau?

2011-10-19T11:33:00.000-07:00

Oberammegau - is a small village in the Bavarian Alps near Germany's border with Austria. In the winter of 1632 the village was struck by the Black Plague, which spread devastation through Europe. By the following summer one-eighth of Oberammega's population of 1,000 people had died. The village elders called all those who could walk to the church and everyone made a vow: "A solemn promise to devote one year in 10 to the preparation and presentation of the tragedy of our Lord's Passion to keep the Christian principle of the redemption of the world before men for all time." There were no more deaths from the plague, and the villagers believed God had heard their vow. Apart from an occasional lapse, due in the main to wars, the village people of Oberammegau have presented their Passion Play every 10 years. The first performance was held in the church in 1634. Nowadays a huge theatre, looking rather like a great aircraft hangar, is used. It seats 6,000 people and has room on the stage for crowd scenes with 500 actors. Only native-born villagers may be considered for the 600 parts in the play. Selection for the principal parts in made by ballot more than 12 months before the performance. Rehearsals begin in May for the first performance in May of the following year. The Passion Play has given Oberammegau worldwide renown and visitors travel long distances to see the eight hours play. The play is divided into episodes. These episodes are introduced by the Passion chorus, which consists of fifty singers. The whole community becomes involved in the production in a completely medieval way.

Where is nought longitude?

2011-10-15T09:28:00.000-07:00

Longitude - nought degrees longitude passes through Greenwich on the River Thames in London, England. 0º longitude is known as the "prime meridian". You can see at Greenwich the prime meridian mark from which all countries have reckoned longitude since 1884. Longitude and latitude are fixed lines crossing the globe by which the location of any place on the earth's surface can be determined and described. Lines of longitude go from north to south. All start at the North Pole and end at the South Pole. Longitude is measured both 180º east and 180º west of the meridian, the two together making the full 360º of the earth's circumference. World time is also measured from Greenwich. Greenwich Mean Time is zero hour and, depending on whether you are west or east of the prime meridian, you are either so many hours behind or ahead of the time of Greenwich. The Royal Observatory at Greenwich was founded in 1675 and was one of Sir Christopher Wren's great designs. In 1960 the building was opened as an astronomical museum.