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.-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.