noun

• 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

  ‘The rocks found in the crust of the continents is called sial.’

  More example sentences

  • ‘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.’