The material of the upper or continental part of the earth's crust, characterized as being of relatively low density and rich in silica and alumina.Contrasted with sima
- ‘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.’
- ‘The rocks found in the crust of the continents is called sial.’
1920s: from the initial letters of silica and alumina.
We take a look at several popular, though confusing, punctuation marks.