Steno and the rock cycle

Abstract

Geologists categorize the basic types of rock according to their origin – igneous, sedimentary, or metamorphic -- rather than by their physical properties. This is expressed dynamically by the fundamental concept of the rock cycle, which describes how the basic rock types are derived from one another within the Earth system as a result of ongoing cyclic geologic processes.  In Nicolaus Steno’s published geological work, particularly De Solido, he takes a similar approach, outlining how a substance can be examined “to disclose the place and manner of its production”. Steno also recognizes the roles of erosion, transport, and deposition in the production of sedimentary strata from pre-existing earth materials. His description and diagrams of the geological evolution of Tuscany also show a clear cyclicity of process. While the modern concept of the rock cycle did not emerge until the 19^th century, Steno’s work contains key elements of this important concept.