Post quem dating
Relative dating of a site's stratigraphy often depends on the absolute dating of excavated materials and artifacts.
One of the most widely used methods of determining the absolute date of organic materials is radiocarbon (carbon 14) dating .
Many of the houses show an internal courtyard, sometimes colonnaded, and a south-facing dining room.
In some cases, a second story is reached by a wooden staircase from the courtyard. There are important examples of pebble mosaic floors, some with mythological scenes, and of a bathroom with pottery tub.
The "or after" is important: if you only find one coin in the pit, you cannot tell if the pit was dug in 1915, 1916, 1960, or any time after 1915, and the coin dropped in.
The phrase terminus post quem is therefore very important to archaeologists.
Archaeologists sometimes use thermoluminescence dating to establish the age of pottery.
An event may well have both a terminus post quem and a terminus ante quem, in which case the limits of the possible range of dates are known at both ends, but many events have just one or the other.
Similarly, terminus ad quem ("limit to which") is the latest possible date of a non-punctual event (period, era, etc.), while terminus a quo ("limit from which") is the earliest.
The concepts are similar to those of upper and lower bounds in mathematics.
For example, consider an archaeological find of a burial that contains coins dating to 1588, 1595, and others less securely dated to 1590–1625.