12) superstratum. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...Inflected forms: pl. suˇperˇstraˇta (-strt, -strat)1. One layer or stratum superimposed on another. 2. Linguistics The language of a later, invading people imposed...

13) thickness. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...two surfaces of an object, usually the dimension of smallest measure. 3. A layer, sheet, stratum, or ply: Each floor is a single thickness of concrete....

14) overburden. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...deposit. b. Sedimentary rock covering older crystalline layers. 3. Archaeology A sterile stratum overlying a stratum bearing traces of the culture being studied....

15) layer. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...on the windowsill; a cake with four layers. b. A usually horizontal deposit or expanse; a stratum: layers of sedimentary rock; a layer of warm air. c. A depth or...

16) class. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...third class. b. A quality of accommodation on public transport: tourist class. 3a. A social stratum whose members share certain economic, social, or cultural characteristics:...

17) seam. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...d. A scar. 2. A line across a surface, as a crack, fissure, or wrinkle. 3. A thin layer or stratum, as of coal or rock. Inflected forms: seamed, seamˇing, seams1....

18) horizon. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...stratigraphic column, such as the location of one or more fossils, that serves to identify the stratum with a particular period. b. A specific layer of soil or subsoil...

19) zone. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...4. Anatomy A ringlike or cylindrical growth or structure. 5. Geology A region or stratum distinguished by composition or content. 6. A section of an area or territory...

20) heave. The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
...waves; an exhausted dog heaving its chest. 7. Geology To displace or move (a vein, lode, or stratum, for example). 1. To rise up or swell, as if pushed up; bulge:...