Outer part of the earth's surface. Siliceous rock; outer part of earth's surface.
In geochemistry and geophysics, the substance of the Earth’s continental crust, as distinct from the sima of the ocean crust. The name, now used rarely, is derived from silica and alumina, its two main chemical constituents. Sial is often rich in granite.
(Géologie) Couche superficielle de la Terre.