Stratum

[Sarah]

A bed of earth or rock of one kind, formed by natural causes,and consisting usually of a series of layers, which form a rock as itlies between beds of other kinds. Also used figuratively.

[Julene]

A layer or a series of layers of rock in the ground.

[Tariq Zaki]

Business intelligence solution that helps analyze, segment, and boost marketing, customer, manufacturing, and financial performances. A software product by Silvon Software

[Luis Fok]

one of the parts or layers into which something is separated: