| May 21, 2003 |
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The Dynamic Earth
We  may not always feel it move under our feet, but make no mistake -- our Earth is a restless planet! It rumbles, grumbles, and continually spews its molten insides beyond the horizon. This pattern of birth, destruction, and renewal is Earth's natural metamorphic process -- and the geological record reveals a stunning history book. This presentation by the National Museum of Natural History seeks to tell the stories behind the rocks we walk on and the gems we covet, and ultimately explain how they were made. Deep in Earth's pressure-cooker core, rocks morph into different minerals, depending on temperature. As magma races to the surface, it faces another set of factors. If the outside temperature is cold enough, the magma crystallizes and can harden into gems. Rocks such as marble, slate, granite, and even sandstone all had previous incarnations somewhere beneath Earth's crust. Next time you kick a pebble or skip a stone, consider how far it traveled to cross your path! (in Geology and Geophysics) |
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