What about ad bc bce and bp ages virtual dating
Uncalibrated radiocarbon ages can be converted to calendar dates by means of calibration curves based on comparison of raw radiocarbon dates of samples independently dated by other methods, such as dendrochronology (dating on the basis of tree growth-rings) and stratigraphy (dating on the basis of sediment layers in mud or sedimentary rock).
Such calibrated dates are expressed as cal BP, where "cal" indicates "calibrated years", or "calendar years", before 1950.
Because the present changes every year, archaeologists, by convention, use A.
(Before the Present) is the number of years before the present.
For example, the entry of humans into the New World during the Pleistocene (Ice Age) is thought to have occurred by about 15,000 years ago, or 15 ka (which is equivalent to approximately 13,000 B.
ka (, thousand years) signifies "thousand calendar years ago," and it is used most often in geological, paleontological, and archaeological reporting to assign a general date to events that occurred a very long time ago.
This has to do with the fact that the level of atmospheric radiocarbon (carbon-14 or C) has not been strictly constant during the span of time that can be radiocarbon-dated.
Radiocarbon years ago may be abbreviated " The Northern hemisphere curve from INTCAL13.