Hum. 300 History and methods of science

How are the Three Kinds of Rocks Formed

There are three different kinds of rocks : sedimentary , metamorphic and igneous rocks . Each of these are formed in a different way

Sedimentary rocks are bits and pieces of eroded earth that are swept away into the bottoms of the different bodies of water like the sea lake and oceans . When these bits of earth settle under the water , they form layers . The weight of the layers on top tend to press down the ones at the bottom and make it more compact . In time , these

will become solid sedimentary rocks . Examples of sedimentary rocks are sandstones limestones , shale , conglomerate and gypsum rocks

Metamorphic rocks were originally either igneous or sedimentary rocks that have been formed into this type because of heavy pressure when they are pushed underneath the other rocks . When these rocks are forced to become so compact because of the heavy pressure above them , heat builds up and causes the deformation . Examples of metamorphic rocks are schist and gneiss

Granite rocks come from volcanic debris that transform into rocks because of slow cooling . This cold change in temperature happens when lava suddenly flows on the ground and traps cooling pockets of magma underneath . The cold temperature cools the lava slowly and forms the granite rocks . Examples of granite rocks are scoria , pumice which are very light and may float on water and obsidian . These three types of granite are also considered to be glass

Reference

Rock Hounds (1999 . The Franklin Institute . Retrieved June 5 , 2007 from http

www .fi .edu /fellows /fellow1 /oct98 /index2 .html

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