The field relationships, as they are called, are of primary importance and all radiometric dates are evaluated against them.
For example, a geologist may examine a cutting where the rocks appear as shown in Figure 1.
When living things die, they stop taking in carbon-14, and the radioactive clock is "set"!
Creationists would generally agree with the above methods and use them in their geological work.From his research, our evolutionary geologist may have discovered that other geologists believe that Sedimentary Rocks A are 200 million years old and Sedimentary Rocks B are 30 million years old.His geological cross-section may look something like Figure 2.Clearly, Sedimentary Rocks A were deposited and deformed before the Volcanic Dyke intruded them.C and counting the amount of each) allows one to date the death of the once-living things.
Perhaps you have heard of Ice Man, a man living in the Alps who died and was entombed in glacial ice until recently when the ice moved and melted.
Radioactive elements were incorporated into the Earth when the Solar System formed.
All rocks and minerals contain tiny amounts of these radioactive elements.
Carbon-14 is a method used for young (less than 50,000 year old) sedimentary rocks.
This method relies on the uptake of a naturally occurring radioactive isotope of carbon, carbon-14 by all living things.
Here he can see that some curved sedimentary rocks have been cut vertically by a sheet of volcanic rock called a dyke.