See more information about "Strata" Smith and his original geologic map of England.Information about Simon Winchester's delightful biography of Smith, The Map That Changed the World is available at Tree-Ring dating is based on the principle that the growth rings on certain species of trees reflect variations in seasonal and annual rainfall.
Because of the distortions and lies spread by fundamentalists about scientific dating there is a need for a centralized source of information on the topic.
A few examples of such lies are presented at the very bottom of this page.
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.
Using relative dating principles and the position of layers within rock, it is possible to reconstruct the sequence of geologic events that have occurred at a site.
In the image below, cliffs along the Snake River show signs of volcanic activity and deposition.
The thick, dark, gray layer at the bottom is made of basalt. You have just used the principle of superposition to interpret the relative ages of the layers.
This principle states that in a sequence of undisturbed sedimentary layers or lava flows, the oldest layers are at the bottom.
This is made up of numerous regional tree-ring chronologies, particularly in the medieval and post-medieval periods, for which the laboratory now has more than 200 reference chronologies from many areas. By comparing the proportion of K-40 to Ar-40 in a sample of volcanic rock, and knowing the decay rate of K-40, the date that the rock formed can be determined.