Fig. 23-5 Uranium-235 and uranium-238 each decay by a series of α particle and β emissions to a stable isotope of lead. Thorium-232 and plutonium-241 have similar multistep decay chains. (From Dickerson and Geis, Chemistry, Matter, and the Universe.)
Fig. 23-8 Plot of carbon-14 decay rate (in counts per minute per gram of carbon from the sample) against the age of the sample in years. This plot is prepared from the equation t = 18.600 log10(15.3/d). It is what is called a semilog plot. Although the vertical axis is marked in units of d, it is really measured in equal units of log10d. Such historically datable points as the Ptolemaic period and the period of Sneferu in Egypt permit us to check the whole concept of radiocarbon dating. The agreement is excellent.