Famous Geologists: Steno

Nicolaus Steno (Niels Stensen; Figure 1) was an anatomist, geologist, and bishop, often considered to be the founder of geology as a science. He was the first to describe the most fundamental principles of stratigraphy and crystallography, and the first to claim by rigorous arguments that fossils are the remains of former life on Earth. Steno’s principle of superposition is simple but fundamental for all geologists and belongs to the first steps of understanding that a geology student must acquire. The principle states that geological strata were originally deposited horizontally under the action of gravity, and that the upper strata are younger than the lower are. The principle also states that inclined or folded strata have been tilted or disturbed subsequent to their deposition. The principle of superposition, theoretically, builds on Steno’s statement that a crystal, sediment layer, or other kind of geological structure that takes the shape of the surface of another solid body is younger than the body from which it takes its shape. In conjunction with the principle of superposition, Steno’s principle of intersection says that a body of rock or other geological structure is younger than those rocks or structures it is found cutting through. Steno held forth yet another important stratigraphic principle, the principle of reconstruction. This states that it is possible to ‘backstrip’ a series of geological changes in reverse order, from the present to the past, having regard to the principles of superposition and intersection. In this way it is possible to obtain....