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What are sedimentary rocks? Shale and limestone

By |2018-10-03T09:50:54+00:00June 26th, 2017|Geology, History|

Sedimentary rocks: Limestone cliffs in Saudi Arabia Before sedimentary rocks 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. More about igneous rocks [...]

What is metamorphic rock? Marble, slate, diamonds

By |2018-05-28T16:21:09+00:00June 26th, 2017|Geology|

What is metamorphic rock? Slate rocks in Cascadilla Gorge, Ithaca, New York Metamorphic rocks form under pressure 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. (Read more [...]