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What is plate tectonics? Earthquakes and volcanoes

By | 2017-09-21T15:19:05+00:00 September 21st, 2017|Geology|

The world as seen from space (flattened out) When you look at a map of the world, it seems as though it was always like that - North America on top of South America, Europe north of Africa, Australia off at the bottom right. But really all of the dry land on Earth moves around like floating shapes about 60 miles [...]

What are sedimentary rocks? Shale and limestone

By | 2017-06-26T02:19:25+00:00 June 26th, 2017|Geology, History|

Limestone cliffs in Saudi Arabia When the Earth was first forming, about six billion years ago, there weren't any sedimentary or metamorphic rocks. The only rocks were igneous rocks like quartz. These formed when melted silica, carbon, and other molecules cooled off and stuck together. But gradually some of these igneous rocks started to [...]

What are metamorphic rocks? Marble, slate, diamonds

By | 2017-06-26T00:52:44+00:00 June 26th, 2017|Geology|

Slate rocks in Cascadilla Gorge, Ithaca, New York About 450 million years ago, some of the sedimentary rocks began to transform into metamorphic rocks. When sedimentary rocks like limestone or shale were under water, the weight of the water pressed them down. Sometimes the weight of the water pressed them so hard that [...]

What is quartz? Igneous rock

By | 2017-06-26T00:11:13+00:00 June 26th, 2017|Geology|

A chunk of white quartz Quartz is an igneous rock made out of molecules of silicon and oxygen atoms held together in a crystal pattern. All of the silica and oxygen that make quartz came originally from the insides of stars, and it shot out of the stars when the stars exploded as [...]

What are igneous rocks? Volcanic stone

By | 2017-06-26T00:06:08+00:00 June 26th, 2017|Geology|

Obsidian tools Igneous means "fiery", and igneous rocks are rocks that were made by heating them up in a fire. Usually that fire is the big fire inside the earth, under the earth's crust. Inside the earth, radioactivity creates very high temperatures of about 1000 degrees Celsius (that's about 1800 degrees Fahrenheit). Because [...]