noun[mass noun] Geology , dated
The material of the upper or continental part of the earth’s crust, characterized as relatively light and rich in silica and alumina. Contrasted with sima.
More example sentences
- The rocks found in the crust of the continents is called sial.
- A mnemonic term derived from for silica, for alumina, and for magnesium, applied as a compositional term to a layer within the Earth that occupies a position intermediate between sial and sima.