sima

غير معدود

A noun referring to the continuous lower layer of the Earth's crust, which is rich in silicon and magnesium.

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1. Lower layer of Earth's crust C2 formal scientific

   The continuous lower layer of the Earth's crust, composed primarily of silica and magnesium, underlying the sial layer.

   • The sima layer is denser than the sial layer above it.
   • Geologists study the sima to understand tectonic plate movements.
   • The composition of sima is rich in silicon and magnesium.

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