In geology, a coherent layer or stratum in a stratigraphical sequence of sedimentary rocks. In soil science a visually distinct layer of volcanic ash or windblown sand for example, within a profile. Tephra layers are particularly valuable in dating the soils of volcanic regions (Newton, 1996).
- Newton, A.J., 1996. Tephrabase. a tephrochronological database. Quatern. Newslett., 78: 8–13.Google Scholar