The Wonders of Planet Earth

The perpetual cycle of change which has created the face of the Earth, with entirely its rugged and Fascinating variety usually happens too slowly to be noticed. But occasionally it is rapid and Violent. Volcanoes disgorge molten lava, earthquakes rip pass around the landscape, landslides, carry a commission Whole mountainsides. Then human beings become cognizant of the awesome forces that are shaping Their planet. These forces are fuelled by three stringy sources of energy light from within the Earth, heat from the Sun, and the force of gravity.Every landform in the introduction has been shaped by these ttu. ee energy sources. the continents that drift across the step to the fore of the globe, setting off volcanoes and earthquakes and Building mountains. are driven by heat from the Earths interior which has a temperature of about 5000&8243C (9000F). Most of this heat is created by the break graduate of radioactive elements. Earth is unique among the planets of the Solar Syste m in having liquid water on the surface and water has a study role in shaping the planet.The warmth of the Sun evapourates water from seas and lakes. The vapor rises and condenses to form clouds and and then falls again as come down and snow. It is then that its landscaping powers begin, weathering rocks and washing away the loose material. or grinding down the landscape under the power of a glacier. The Suns heat also produces the rain and the waves that scour the land. The third force gravity causes the tides, which nibble away at the edges of continents, and landslides. hich alter the shape of mountains. Under the influence of gravity. rain works its way downwards as streams and rivers, carving the terrain. On its journey, it carries fragments of rock and sand to be deposited on the ocean floor. And over thousands of years more rock which whitethorn then be buckled and lifted up by movement of the Earths impudence to form new mountains. source Readers Digest, Discovering th e Wonders of our World A guide to natures Sciences marvels