Methods scientific dating
However, human beings love to see factual precision, and we want to know how old something is.
Please remember that all dating methods, even those termed "absolute," are subject to margins of error. That is a very small amount of possible error range. Modern studies almost always use two or more methods to confirm dating work and to build confidence in the results obtained.
Relative dating methods are used to determine only if one sample is older or younger than another.
Absolute dating methods are used to determine an actual date in years for the age of an object.
Using the potassium-argon method, Fitch and Miller were the first to measure the age of the tuff.
Their result of 212–230 million years did not agree with the age of the fossils (elephant, pig, ape and tools) so they rejected the date.
This new date agreed with the appearance of the new skull.This method is based on the assumption (which nearly always holds true) that deeper layers of rock were deposited earlier in Earth's history, and thus are older than more shallow layers.The successive layers of rock represent successive intervals of time.Later, this date was confirmed by two other dating methods (paleomagnetism and fission tracks), and was widely accepted.Then Richard Leakey found a skull (called KNM-ER 1470) the KBS tuff, a skull that looked far too modern to be 3 million years old.
Far from being data, these dates are actually interpretations of the data.