Geologists still use Steno's principles, with some refinements and additions.They are summarized as the Principles of Relative Geologic Age Determination, sometimes referred to as the Principles of Relative Dating.Ask yourself how the things that are happening in the world today might end up being recorded in the sediments that are now or soon will be deposited.How would today's sediments appear to a geologist millions of years in the future examining outcrops of sedimentary rock that originated in our time? If you did it like many people, you based your sentences on what you know normally happens when you make a lunch.This is similar to what geologists do to determine age.
Relative dating is determining whether an object is older or younger than other objects or events.Imagine that throughout your life youve taken many pictures. Certain groups of fossil animals and plants occur in the geologic record in a specific order.Rather than putting them into a photo album they are stacked up in a box. If a scientist finds one of those fossils, they can then assume the age of the rock based on the age of the fossil.Principles of Stratigraphy Stratigraphy is the study of strata (sedimentary layers) in the Earth's crust.Geologist in the 1800s worked out 7 basic principles of stratigraphy that allowed them, and now us, to work out the relative ages of rocks.