This principle presumes that the oldest layer of a stratigraphic sequence will be on the bottom and the most recent, or youngest, will be on the top.
The earliest-known hominids in East Africa are often found in very specific stratigraphic contexts that have implications for their relative dating.
The concept is considered by uniformitarian geologists to be a major breakthrough in scientific reasoning by establishing a rational basis for relative time measurements.
However, unlike tree-ring dating -- in which each ring is a measure of 1 year's growth -- no precise rate of deposition can be determined for most of the rock layers.
...65 Ma Geologic provinces Shield Platform Orogen Basin Large igneous province Extended crust Geology (from Greek Î³Î·- (ge-, the earth) and Î»Î¿Î³Î¿Ï (logos, word, reason)) is the science and study of the solid matter of the earth, its composition, structure... Beds with a particular fauna can be correlated with others that share it (often globally), and also distinguished from upper and lower beds without them.
Estimates of the order of prehistoric and geological events were determined by using basic stratigraphic rules, and by observing where fossil organisms lay in the geological record, stratified bands of rocks present throughout the world. Though relative dating can determine the order in which a series of events occurred, not when they occurred, it is in no way inferior to radiometric dating; in fact, relative dating by biostratigraphy is the preferred method, and is in some respects more accurate.(Stanley, 167-9) The principles of Relative dating use a combination of fossil study and structural interpretation to learn about the geological history of an area.
Cultural seriations are based on typologies, in which artifacts that are numerous across a wide variety of sites and over time, like pottery or stone tools.
If archaeologists know how pottery styles, glazes, and techniques have changed over time they can date sites based on the ratio of different kinds of pottery.
He concluded, after studying rocks at many outcrops, that each layer represented a specific interval of geologic time.
Further, he proposed that wherever un-contorted layers were exposed, the bottom layer was deposited first and was, therefore, the oldest layer exposed; each succeeding layer, up to the topmost one, was progressively younger.