Radioactive dating geology
A specialized form of cross-dating, using animal and plant fossils, is known as biostratigraphy.
Keyed to the relative time scale are examples of index fossils, the forms of life which existed during limited periods of geologic time and thus are used as guides to the age of the rocks in which they are preserved.
Be sure to see An Animated Isochron Diagram, or, Watching a Rock Age on an Isochron Diagram. Radiometric Dating from The Evolution Evidence Page.
Dating is not necessary to demonstrate that evolution is a fact.See Oldest Living Organism.] The Sheffield Laboratory now has a continuous master sequence for England going back to about 5000BC. This article should be a "must read" for any person interested in factualy accurate information on dating methods.This is made up of numerous regional tree-ring chronologies, particularly in the medieval and post-medieval periods, for which the laboratory now has more than 200 reference chronologies from many areas. By comparing the proportion of K-40 to Ar-40 in a sample of volcanic rock, and knowing the decay rate of K-40, the date that the rock formed can be determined.The implications of this geology for construction of the A303 and the archaeology of the area are discussed.Because of the distortions and lies spread by fundamentalists about scientific dating there is a need for a centralized source of information on the topic.