1. The formation of layers in sedimentary rocks through biological, chemical, or physical changes in the sediments forming them.
2. The formation of layers, castes, classes, or other types of strata.
3. A situation or condition where something is arranged in several strata.
4. A layered arrangement or appearance of successive rock strata.
5. The storing of seeds in a chilled moist environment or material in order to induce germination or to preserve them.
6. In hydrology, the arrangement of water masses in a lake or other body of water into two or more horizontal layers having different characteristics.
7. The formation of layers in snow, ice, or firn as a result of snow sedimentation or other processes [a "firn" is a loose, permeable, granular material that is over a year old, and which is transitional between snow and glacier ice].