Nicolas steno relative dating
The unconformity was discovered by James Hutton in the 1700s.Hutton saw that the lower rock layers are very old. There are no layers in between the ancient and recent layers.You can clearly see the same rock layers on opposite sides of the canyon.The matching rock layers were deposited at the same time, so they are the same age. In most families a person’s age fits into his or her generation: Siblings are around the same age as are first cousins. The arid climate means that that the rocks are not covered by vegetation.
Stratigraphy is the study of rock layers (strata) deposited in the earth.
It is one of the most challenging of geologic subdisciplines, comparable to an exacting form of detective work, yet it is also one of the most important branches of study in the geologic sciences.
Earth's history, quite literally, is written on the strata of its rocks, and from observing these layers, geologists have been able to form an idea of the various phases in that long history.
Sediments were deposited in ancient seas in horizontal, or flat, layers.
If sedimentary rock layers are tilted, they must have moved after they were deposited.
Remember Nicholas Steno, who determined that fossils represented parts of once-living organisms? Superposition refers to the position of rock layers and their relative ages (Figure below).