A summary of the physical phenomena involved in radiocarbon dating is given. Laboratory procedure determines the amount of radioactiue carbon a sample contains now. Calculation of an age requires an assumption concerning the relative amount of radioactive carbon in the environment at the time the organism from which sample was derived was living. The year A.D. 1850 is chosen as a standard since up to then man had not contaminated the air by either adding carbon dioxide from industrial fuel or neutrons from atomic explosions. Thus a decrease to one half of the amount found in A.D. 1850 samples indicates a radiocarbon age of 5730 years. Correlation with tree-ring dating shows a fair degree of accuracy to about 59 B.C. Attempts to correlate Bristlecone Pine growth-rings with radiocarbon age show a discrepancy of 500 to 1000 years, the pine ages being that much older than Carbon-14 ages. Reliable conversion between historical age and radiocarbon age goes back only 3-4000 years. Though only approximations, farming increased rapidly in 1200 “years” from 7,200 to 5,000 B.P. Evidently prior to the Flood the relative amount of Carbon-14 in the air was only about 1/1000 of its present value. Several theories for increase in Carbon-14 are given.