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The '''Earth's crust''' is the geological outer layer of the [[Earth]]. There are two types of crust: continental and oceanic.

The '''Earth's crust''' is the geological outer layer of the [[Earth]]. There are two types of crust: continental and oceanic.

Continental crust is made up of less dense materials than oceanic crust and is generally much thicker (generally 25-75km thick as opposed to oceanic 6km). The thickest crust is found underneath the Himalayan [[mountain]] chain where the roots of the mountains extend to around 75km.<ref>USGS: [http://earthquake.usgs.gov/research/structure/crust/index.php Earth's Crust]</ref>

Continental crust is made up of less dense materials than oceanic crust and is generally much thicker (generally 25–75&nbsp;km thick as opposed to oceanic 6&nbsp;km). The thickest crust is found underneath the Himalayan [[mountain]] chain where the roots of the mountains extend to around 75&nbsp;km.<ref>USGS: [http://earthquake.usgs.gov/research/structure/crust/index.php Earth's Crust]</ref>

Continental crust is also much older than oceanic. The oldest crust in existence today is found in [[Australia]] and has an apparent age of 4.4 billion years<ref>EarthScope: [http://www.gps.caltech.edu/~enadin/Writing/ES_OldestCrust.pdf The Oldest Crust on Earth]</ref>. Many believe that the [[Bible]] discredits the notion that the Earth is billions of years old.

Continental crust is also much older than oceanic. The oldest crust in existence today is found in [[Australia]] and has an apparent age of 4.4 billion years.<ref>EarthScope: [http://www.gps.caltech.edu/~enadin/Writing/ES_OldestCrust.pdf The Oldest Crust on Earth]</ref> Many believe that the [[Bible]] discredits the notion that the Earth is billions of years old.

==References==

==References==

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[[Category:Geology]]

[[Category:Geology]]