Another universally recognized constraint is the level of carbon-14 in geologically old material.Although the existence of a very low level of carbon-14 in ancient or antediluvian fossil material, for example Pennsylvanian coal (conventional age ~350,000,000 years) is controversial (see discussion below), it is universally agreed that the level of carbon-14 in such materials is at least very low, if not non-existent.

Cal Pal-Online is developed to give a quick reference.

For more detailed results, graphical output and different 14C calibration methods, download and use Cal Pal-Beyond the Ghost.

In this paper I will discuss eight categories of carbon-14 models and their experimental implications.

Six, or three-quarters of these, are creationist models.

The model initially proposed was strictly uniformitarian (Libby 1955).

This simple model is no longer supported by any worker in the field.The C/C ratio in the biosphere had been slowly dropping over the 100-200 years prior to the nuclear age, apparently due to the introduction of essentially "dead" carbon from the use of fossil fuels (coal, oil, natural gas, etc. The C/C ratio between 15, or the increase between 16, has not been correlated with any causative human activity.Recent, more precise measurements of the half-life of carbon-14 are closer to 5730 years than to the 5568-year half-life used in earlier calculations.The calibration algorithm will calculate the same results as Cal Pal-Beyond the Ghost.Due to programming details there will be minor differences.According to this model, plants that get their carbon from the atmosphere would incorporate carbon with a constant C/C ratio.