List of time periods

The categorization of the past into discrete, quantified named blocks of time is called periodization. This is a list of such named time periods as defined in various fields of study. These can be divided broadly into prehistoric periods or archaeological periods for the time before the development of writing, and historical periods, starting when written records began to be kept. The existence of written sources, however, doesn't at all exclude differences in periodization between archaeology and history. In archaeology and anthropology, prehistory is subdivided into the three-age system. This list includes the use of the three-age system as well as a number of various designations used in reference to sub-ages within the traditional three. The dates for each age can vary by region. On the geologic time scale, the Holocene epoch starts at the end of the last glacial period of the current ice age (c. 10,000 BC) and continues to the present. The beginning of the Mesolithic is usually considered to correspond to the beginning of the Holocene epoch. Geological periods Era Precambrian Hadean (or hadaeozoic[citation needed]) Archean (or archaeozoic) Eoarchean Paleoarchean Mesoarchean Ne