Looking at the graph, 100% of radiocarbon in a sample will be reduced to 50% after 5730 years.
In 11,460 years, half of the 50% will remain, or 25%, and so on.
In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
In fact, levels of Carbon-14 have varied in the atmosphere through time.
One good example would be the elevated levels of Carbon-14 in our atmosphere since WWII as a result of atomic bombs testing.
Long tree-ring sequences have been developed throughout the world and can be used to check and calibrate radiocarbon dates.
An extensive tree-ring sequence from the present to 6700 BC was developed in Arizona using California bristlecone pine (), some of which are 4900 years old, making them the oldest living things on earth.
Absolute dating represents the absolute age of the sample before the present.
Historical documents and calendars can be used to find such absolute dates; however, when working in a site without such documents, it is hard for absolute dates to be determined.When it comes to dating archaeological samples, several timescale problems arise.For example, Christian time counts the birth of Christ as the beginning, AD 1 (Anno Domini); everything that occurred before Christ is counted backwards from AD as BC (Before Christ).Rodents, for example, can create havoc in a site by moving items from one context to another.Natural disasters like floods can sweep away top layers of sites to other locations.The Greeks consider the first Olympic Games as the beginning or 776 BC.