Geologic Time Quiz

Atoms with the same number of protons but differ in the number of neutrons.

when certain unstable nuclei spontaneously break apart or decay

The amount of time it takes for ½ of the nuclei in a sample to decay to a stable isotope

a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.

dating materials using the sequence or order in which events occurred

the forces and processes that we observe today have been at work for a very long time

in an undeformed sequence of sedimentary rocks, each bed is older than the one above it and younger than the one below it

means that layers of sediment are generally deposited in a horizontal position (layers)

when a fault cuts through rock layers, or when magma intrudes other rocks and crystallizes, we can assume that the fault or intrusion is younger than the rocks affected

rocks containing inclusions are younger than the inclusions they contain