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.William "Strata" Smith, a civil engineer and surveyor, was well acquainted with areas in southern England where "limestone and shales are layered like slices of bread and butter." His hobby of collecting and cataloging fossil shells from these rocks led to the discovery that certain layers contained fossils unlike those in other layers.Cross-dating is a technique used to take advantage of consistencies in stratigraphy between parts of a site or different sites, and objects or strata with a known relative chronology.A specialized form of cross-dating, using animal and plant fossils, is known as biostratigraphy.For each dating or chronological method there is a link in the box at right to take you to that section of this page.
Earth's oldest living inhabitant "Methuselah" at 4,767 years, has lived more than a millennium longer than any other tree.
Overview of Methods Superposition Stratigraphy Dendrochronology Radiocarbon C14 Radiometric Dating Methods Obsidian Hydration Dating Paleomagnetic/Archaeomagnetic Luminescence Dating Methods Amino Acid Racemization Fission-track Dating Ice Cores Varves Pollens Corals Cation Ratio Fluorine Dating Patination Oxidizable Carbon Ratio Electron Spin Resonance Cosmic-ray Exposure Dating This is an excellent overview of dating methodologies, and is a chapter in a textbook on Archaeology.
You may find it useful for the clear definitions, and for excellent links on a variety of topic.
It excludes contamination and weathering of travertines and makes possible more precise dating of thin deposits of secondary carbonates.
No web-based resource for this method is available.