1. The study of layers, or strata, in the EarthJim was very interested in the geological and cultural history of the planet Earth so he decided to take a course in stratigraphy.
2. The interpretation of the vertical layering in an archeological site on a geological deposit that allows scientists to relatively date the artifacts or fossils in the layers (strata): Borrowed from geology, stratigraphy assumes that older layers are generally found on the bottom. This means that artifacts found in the upper layers of an excavation are likely to be younger than those in the lower layers.