Niels Steensen ; 1 January 1638 – 25 November 1686 [NS: 11 January 1638 – 5 December 1686]) was a Danish scientist, a pioneer in both anatomy and geology who became a Catholic bishop in his later years.
Portrait of Niels Steensen (1666–1677). Unsigned but attributed to court painter Justus Sustermans. (Uffizi Gallery, Florence, Italy).
De solido intra solidum naturaliter contento dissertationis prodromus (1669)
Elementorum myologiae specimen: Illustration from Steensen's 1667 paper comparing the teeth of a shark head with a fossil tooth.
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithostratigraphy, biostratigraphy, and chronostratigraphy.
The Permian through Jurassic strata of the Colorado Plateau area of southeastern Utah demonstrate the principles of stratigraphy.
Engraving from William Smith's monograph on identifying strata based on fossils
Strata in Cafayate (Argentina)
Chalk layers in Cyprus, showing sedimentary layering