Key Principles of Relative Dating
Skip to local navigation Skip to main content. Search Website Search Directory. UVM Home Chesapeake Bay: An Evolutionary Study In Geologic Time Teacher Resources What are the four laws of relative dating Asked Questions What is a Fossil? How Geologists Tell Time The Evolving Planet Evolution in the News Classroom Resources. These techniques were first articulated by Nicolas Steno, a Dane living in the Medici court of Italy in the 17th C. Law of Superposition In a sequence dting rock strata, the oldest layer will lie below or underneath the youngest.
Click on photo to enlarge: Law of Original Horizontality Layers of sediment, such as you would have in the bottom of a lake, or the ocean, are deposited by gravity into flat layers. Law of Cross-Cutting If a rock layer is cut by a fault or igneous intrusion, the rock that is cut must be older than the dsting that cuts it.
Law of Lateral Continuity Rock layers will extend outwards until the environment that produced them changes. For classroom activities based on using Steno's Laws to examine relative geologic time click here sampleactivity.