Abstract
The essential ideas behind the major methods for assessing the relative ages of geological and archeological materials and events are reviewed. These include the principles of original horizontality, superposition, inclusion, cross-cutting relations, and cross-dating by index fossils (biological succession) or artifacts. Some general principles of absolute dating are introduced, and, as representatives of non-radiometric methods, tree-ring, thermoluminescence, obsidian hydration, and amino acid racemization dating are discussed with examples.