There are three main assumptions that must be made to accept radiometric dating methods.
These must be accepted on faith in uniformitarian and naturalistic frameworks.
Relative time places events or formations in order based on their position within the rock record relative to one another using six principles of relative dating.
Relative time can not determine the actual year a material was deposited or how long deposition lasted; it simply tell us which events came first.
Long before geologists tried to quantify the age of the Earth they developed techniques to determine which geologic events preceded another, what are termed "relative age” relationships.
These techniques were first articulated by Nicolas Steno, a Dane living in the Medici court of Italy in the 17th C.
Geologic time covers the whole sweep of earth's history, from how and when the earth first formed, to everything that has happened on, in, and to the planet since then, right up to now.
Geologists analyze geologic time in two different ways: in terms of relative geologic age, and in terms of absolute (or numeric) geologic age.The units commonly used for geologic age are mega-annum (Ma) for millions of years, giga-annum (Ga) for billions of years, and kiloannum (ka) ka for thousands of years.Because these units are used according to the rules of the metric system, the M in Ma and the G in Ga must be capitalized, and the k in ka must not be capitalized.With this in mind geologist have long known that the deeper a sedimentary rock layer is the older it is, but how old?Although there might be some mineral differences due to the difference in source rock, most sedimentary rock deposited year after year look very similar to one another.Far from being data, these dates are actually interpretations of the data.