1) An overlying stratum or layer 1) Exteriority 
Su`per·stra'tum noun ; plural Superstrata [ New Latin : confer Latin supersternere , superstratum , to spread upon. See Super- , and Stratum .] A stratum, or layer, above another. 
an overlying stratum or layer. · a set of features of a language traceable to the influence of a language formerly spoken within the same society by a dominant group:Cf. English has a Norman-French superstratum.