For*ma"tion (?), n. [L. formatio: cf. F. formation.]
The act of giving form or shape to anything; a forming; a shaping.
The manner in which a thing is formed; structure; construction; conformation; form; as, the peculiar formation of the heart.
A substance formed or deposited.
4. Geol. (a)
Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.
A group of beds of the same age or period; as, the Eocene formation.
The arrangement of a body of troops, as in a square, column, etc.
© Webster 1913.