A relative-dating principle stating that a geological feature which cuts through another, a fault, a fracture, an igneous intrusion, must be younger than the feature it cuts. Nicolas Steno's 1669 Dissertationis prodromus, the same short work that stated original horizontality and superposition, contains an early statement of the idea; James Hutton formulated it more explicitly in Theory of the Earth (1795), and Charles Lyell folded it into the systematic relative-dating toolkit of Principles of Geology (1830). Alongside superposition, original horizontality and faunal succession, it lets a geologist read the order of events in a rock face with no instrument at all, and it still anchors radiometric dating today: a rock unit crossed by a datable dike or vein has its own age bracketed between older and younger bounds.
Facts
Origin YearSteno's 1669 Dissertationis prodromus is credited with an early statement of the principle, matching the origin-year already recorded on this atlas's sibling entities Law of Superposition and Principle of Original Horizontality; Hutton's Theory of the Earth (1795) gave it its more explicit modern formulation. Cross-Tradition Connections
Associated With
Lyell folded the principle into the systematic relative-dating toolkit of Principles of Geology (1830).
Sibling relative-dating principles from the same stratigraphic toolkit; superposition orders undisturbed horizontal layers, cross-cutting relationships orders a feature against whatever it cuts through.
Steno's 1669 Dissertationis prodromus contains an early statement of the idea, alongside his statements of superposition and original horizontality.
Together with superposition and original horizontality, the four principles are the classical relative-dating toolkit a geologist applies to a rock face with no instrument at all.
Both trace to Nicolas Steno's 1669 Dissertationis prodromus.
Proposed By
Hutton formulated the principle more explicitly in Theory of the Earth (1795), after Steno's earlier, less formal 1669 statement.
Sources
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