| Rating | Solver | Clue |
|---|---|---|
| SUBSOIL | Earth layer | |
| TOPSOIL | Uppermost earth layer | |
| OZONE | Earth's protective layer | |
| SOIL | Top layer of earth | |
| CRUST | Outermost layer of the earth | |
| MANTLE | Middle layer in the earth's internal structure | |
| SLOAM | A layer of earth between coal seams. | |
| UNDERSTRATUM | The layer, or stratum, of earth on which the mold, or soil, rests; subsoil. | |
| SUBSTRATUM | That which is laid or spread under; that which underlies something, as a layer of earth lying under another; specifically (Agric.), the subsoil. | |
| LAYER | That which is laid; a stratum; a bed; one thickness, course, or fold laid over another; as, a layer of clay or of sand in the earth; a layer of bricks, or of plaster; the layers of an onion. | |