Between the years of 17, James Hutton and William Smith advanced the concept of relative dating.
Hutton, a Scottish geologist, first proposed formally the fundamental principle used to classify rocks according to their relative ages.
Using these key or index fossils as markers, geologists began to identify a particular layer of rock wherever it was exposed.
Because fossils are believed to record the slow but progressive development of life, geologist use them to identify the relative age of rocks throughout the world.
After the uplift of the land, the forces of erosion attacked the highlands and the eroded rock debris was transported and redeposited in the lowlands.
During the same interval of time in another part of the world, the land surface subsided and was covered by the seas.
Relative dating is an older method of placing events on the calendar of time.
Artifacts from the earliest dates are in the lower levels or strata of Earth.
Relative dating uses a combination of fossil studies and structural interpretation to draw conclusions about the geological history of an area.With the sinking of the land surface, sediments were deposited on the ocean floor.Such recurring events as mountain building and sea encroachment and believed to be recorded in rock layers that comprise units of geologic time.Geologists have divided the Earth's history into Eras -- broad spans based on the general character of life that existed during these times -- and Periods -- shorter spans based partly on evidence of major disturbances of the Earth's crust.The "relative" positions of layers and fossils to assign estimated dates to strata.Therefore, the actual length of geologic time represented by any given layer is usually unknown or, at best, a matter of opinion.William Smith's collecting and cataloging fossil shells from rocks led to the discovery that certain layers contained fossils unlike those in other layers (see: fossil sorting).It only sequences the age of things or determines if something is older or younger than other things.Some types of relative dating techniques include climate chronology, dendrochronology, ice core sampling, stratigraphy, and seriation.Continue Reading In the field of archeology, the term "absolute" is somewhat misleading.Chronometric or calendar dating is a better choice.