What is a "sima" and a "sial"? and how are they different?

rocky Tina

Dear Tina,

Sima is the a petrologic (rock) name for the lower layer of the Earth's crust. This layer is made of rocks rich in (si)lica and (ma)gnesium. Sial is the a petrologic (rock) name for the upper layer of the Earth's crust. This layer is made of rocks rich in (si)lica and (al)uminiium.

Steve Mattox, University of North Dakota

Source of Information:
 Bates, R.L., and Jackson, J.A., 1987, Glossary of geology: American Geological Institute, Alexandria, Virginia, 788 p.

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