Stratum

str a'tum, re.; pi. -ta, -ta. (Geol.) A layer earth or rock of any kind, formed by natural causes, esp. when it is one of a series of layers. A bed layer artificially made. — Strat'ify, str at'T-fi, v. [-fied (-fid), -fying.] To form or deposit in layers, as substances in the earth; to lay in strata. — Strat'ifica'tion, re. State of being formed into layers the earth; act of laying in strata; proce of being arranged in strata or layers. — Strafiform, a. Having the form of strata.