A Preliminary Discourse Concerning a Solid Body Enclosed by Processes of Nature Within a Solid

Nicolaus Steno's work, "The Prodromus of Nicolaus Steno's Dissertation Concerning a Solid Body Enclosed by Process of Nature Within a Solid", published in 1669, is a foundational text in geology. In it, Steno proposed that fossils are the remains of ancient organisms and that many rocks form from sedimentation. He also articulated key principles of stratigraphy, including the principle of superposition, which states that in undisturbed rock layers, the oldest are at the bottom and the youngest are at the top. Steno's insights revolutionized the understanding of Earth's history and the formation of rocks.123