But other timekeeping methods exist and are still used in the modern world, circumventing the easy processing of dates and history between cultures.
Throughout history, time has been defined in a variety of ways: by everything from the current ruler, or empire, or not defined at all.
This 'law of superimposition' works in the well-defined layers of the Willandra lunettes, but only dates objects as younger or older than adjacent layers.
This well known method was the first technique that became available for accurate dating of old materials. Different cultures around the world record time in different fashions.According to the Gregorian calendar, it is the year 2009 AD. The Kaliyuga Hindu Calendar maintains it is 5110, the Islamic calendar 1430 and the Persian, 2630.In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.Although relative dating can work well in certain areas, several problems arise.Artefacts and other materials can be dated in relative terms by observing which layer of sediments they are found in.