Walther's_law
Facies
Body of rock with specified characteristic
In geology, a facies (/ˈfeɪʃɪ.iːz/ FAY-shih-eez, US also /ˈfeɪʃiːz/ FAY-sheez; same pronunciation and spelling in the plural)[lower-alpha 1] is a body of rock with distinctive characteristics.[1] The characteristics can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formation) and the changes that may occur in those attributes over a geographic area. A facies encompasses all the characteristics of a rock including its chemical, physical, and biological features that distinguish it from adjacent rock.[2]
The term "facies" was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy,[3] which replaced the earlier notions of Neptunism.