geophysics (earth science)

The Continents

The continents of the earth were once shaped very differently to the way they are now. This is because the earth has a molten lava center, upon which the crust of land and sea masses 'float'. This material of molten rock is known as magma, and it allows the surface of the earth, both under the sea, and above, to shift, from time to time, in response to the tremendous heat and pressure which lies at the heart of the planet. See The Dynamic Earth.

The underside of the earth's surface exists as a series of interlocking rock plates, known as Tectonic Plates. Pressure events on earth manifest themselves as earthquakes, volcanoes and also, in a less violent way, in tectonic drift, which occurs because the continents move continuously, perhaps a few meters every year. See the earthquake locator. The study of earth's subterranean forces is called seismology.

Earthquakes, volcanic eruptions, meteorite strikes, and violent storms, such as hurricanes, typhoons and cyclones, are all classified as natural disasters, which can cause flooding, high winds, and large waves in our oceans, also known by the Japanese word for a huge tidal wave, Tsunami. The effect of these waves striking land can be extremely destructive to man and the environment. Weather related events such as hurricanes and cyclones are normally confined to certain climactic regional area's of the earth, such as the monsoon regions, or the tropics, and often originate over the world's oceans. Courses in the study of meteorology can be taken as part of online degree programs or at colleges around the country. Seismologists and volcanologists need M.S. or Ph.D. advanced online degrees in order to be experts in their respective fields. Distance education and online degrees have opened up many doors for busy and part time students to get the education and degrees they want. 

About 750 million years ago, the suface of the earth was dominated by one so-called 'supercontinent', Rodinia, which was surrounded by a single ocean, called the Iapetus Ocean.

This supercontinent subsequently fragmented, giving rise to the continents of Pannotia, Siberia, and North China. From Pannotia in turn came the continents of Laurentia, Gondwana, and Baltica. About 350 million years ago, the continents of Gondwana, Euramerica and Siberia drifted together again, colliding to form the supercontinent of Pangea during the Devonian and Carboniferous periods. See the geological time line.

The Dinosaurs

At that time, it is known, dinosaurs roamed widely over the earth. Although the continent of Pangea began to drift apart almost immediately, the process of separation was prolonged for some 250-300 million years, from the Jurassic / Triassic period until the mid-Cretaceous period some 120 million years ago, Gondwana giving us the smaller landmasses of Australia, India, South America, Africa, and Antarctica that make up a part of the world map we know today.

The reign of the dinosaurs finally came to an end. Some catyclysmic event, such as a massive meteor strike or a global flood, may have introduced a new ice age to the planet, and caused the subsequent demise of the race of dinosaurs. What this event may also have done, is to disturb the rock mantle of earth's crust, further contributing to the end of the last supercontinental era. Many bones, skeletons and fossils have been found from this time, which can be viewed in museums around the world. The study of the history of life is known as paleontology.


Earth's crust is composed of different types of material. Sedimentary rock is formed by water pressure on sand and gravel. Igneous rock, such as granite, is formed by the cooling of volcanic lava after an eruption. Some material remains from the original stellar explosion that spawned the planet. Large concentrations of mineral deposits exist in the earth's surface. These include gold, oil, platinum, diamonds, coal, and silver, and many others. The study of earth's rock formations and minerals is called geology. See the Mineralogy Database. For a full list of known elements, see the periodic table. For an overview of South African minerals, see the S.A. Council for Geoscience.


Man has evolved in the place of the dinosaurs, and conquered the planet, linking the six continents with technology, and residing on five of the six major landmasses, Asia, Africa, America, Australia and Europe. Antartica is by international agreement used only for scientific research and therefore is only populated by a small number of scientists. Mass housing complexes and mining operations are not permitted on Antartica.


Earth exists within a fragile and complex structure of seismology, meteorology, ecology, biology, astronomy, physics and politics. Weather patterns, seismic events and biological developments are closely monitored. A large amount of meterological data is supplied to the world by space agency, NASA and the European Space Agency (ESA). The surface of the earth may be viewed through satellite images by obtaining free software from Google Earth. France can be viewed at Geoportal.

Earth as an entity may also be a living organism, with ecology being the lifeblood of the planet. See The Gaia Theory.

Our planet is subjected to many stresses which have raised serious environmental concerns. One group which keeps a watch on the environment is Greenpeace and another is the Climate Change Education Group.

The earth is being taxed by three main effects, Global Warming caused by mainly CFC and carbon dioxide emissions, Global Dimming, caused by the number of airborne particles in our atmosphere, and which actually cools the planet, and World Population Growth which occurs because of human reproduction.

Global dimming is generally decreasing owing to well-intentioned platinum exhaust filters for vehicles and other initiatives designed to reduce particle emissions. Unfortunately, this trend also contributes towards global warming, causing scientists to radically revise future global warming predictions up to an increase of 10 degrees centigrade within the next 20 years. Sea levels are beginning to rise by increasing amounts every year.


Burgeoning economies such as China, South East Asia, and Southern Africa are requiring more and more electricity to service computer networks, televisions and air-conditioning. Power companies are struggling to meet demand from consumers in these areas. If "dirty" fuels such as coal, oil and gas are utilised to fill this demand, the earth will suffer even more than it already has. Global warming needs to be reduced, global temperature rises need to be contained. An increase in ocean levels of 8-10 meters, because the north pole Arctic ice has melted, for example, would be as catastrophic to the earth as a large meteor or asteroid strike causing a tsunami.

Energy conservation has become increasingly important to prevent this type of catastrophe. Nuclear power is an option, but needs responsible management. Nuclear energy is produced in an efficient process, in that it produces more power, or electricity, than heat by-products, but spent and radioactive fuel rods are difficult to dispose of. Tension and international suspicion in the political arena have restricted some nations from speedily acquiring mass electricity for their people from nuclear sources, even though this might benefit the planet ecologically as a whole.

For concerned and resourceful individuals and citizens, there are other options that might be available to you for protection against power blackouts, options that might contribute to your self-sufficiency and that may assist to ensure the future health of the planet. Alternative power options do, however, require considerable research on the part of the individual. See

Solar Panel Plans and Windmill Energy.

Some continents are more prosperous than others. Continents such as Africa, and parts of Asia, largely marginalised by the rest of the world, have had to come up with innovative ways to survive. Southern Africa has some of the world's most advanced and innovative power generation capabilities, with new wind farms and solar projects being established regularly. See Science In Africa, Applied 3rd World Science and Eskom, who are committed to sustainable and stable enegy policies, as well as renewable energy projects, and, in spite of their 2007 difficulties with supply, have recovered admirably, with almost negligible power-outages in 2008.

The Future

The Earth is a source of never-ending wonder and beauty. Wildlife programs, such as National Geographic and the BBC, enjoy a large viewership, and new species of life on our planet are still being discovered on a regular basis, which does not alter the fact that many species on our planet are also on the verge of extinction. Over-population and food supplies may become a serious problem in the near future - the efficiency and economy of the global food supply and the existing distribution chains are currently in the hands of the WTO, who set the rules. The future of the planet is now, as it has been for the last 50 years or so, in the hands of a few powerful politicians. They hold the fate of the planet in their hands. Let us hope they can make brave choices for the good of the planet, as a whole, and ensure the survival of our species.

For information on the latest seismological and other scientific news on planet earth, see the New Scientist, as well as Science In Africa.

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