See also, on this website, articles on the ages of the geologic periods (Ages), radiometric dating (Radiometric dating), the reliability of radiometric methods (Reliability), a "time machine" for studying the distant past (Time machine) and the "uniformitarian" assumption and how it relates to evolution and the age of the earth (Uniformitarian).
Different cultures around the world record time in different fashions.
Some ill-fated attempts to define time even attempted to count backwards through the genealogies of the Bible, establishing a series of dates which remain a cause of confusion.
These various chronologies and their inherent inconsistencies, known as ‘relative dates,’ are a constant series of hurdles in the quest of historians and archaeologists to record mankind’s existence on earth.
Also, at least one of these dates comes from a hide that had been soaked in glycerin, rendering the date invalid.