Stratigraphy

Part of speech: noun

Pronunciation: /stɹəˈtɪɡ.ɹəfi/

Definitions

1. The study of rock layers and their sequence to determine the age and history of geological formations
2. The scientific discipline analyzing sequential layers of sediment and rock to establish temporal relationships and reconstruct Earth's past environmental conditions
3. The examination of stacked geological strata arranged in order to deduce chronological sequences and interpret the depositional history of landscapes

Etymology: Stratigraphy is a plain compound built from two classical parts. The first, "stratum," is the Latin word for a layer or covering, a form of "sternere," "to spread out" or "to lay down," and the second, "-graphy," comes from Greek "graphia," "writing" or "description," so the literal sense is something like "writing about layers." The combination appeared in the mid-nineteenth century, between roughly 1841 and 1865, when geologists were working out how rock strata could be read as a historical record. That is the key shift: the word did not describe a method of writing at all, but a method of reading the ground. Each layer of sediment or rock was treated as a page, and its position relative to the layers above and below was used to determine which came first. The suffix "-graphy" had long been attached to descriptive sciences such as geography and topography, so the form was familiar to scholars of the period.

Synonyms: layering, geology