absolute age
the numerical age, in years, of a rock or object
eon
longest subdivision in the geological time scale
epoch
next-smaller division of geologic time, but smaller than a period
era
a large division of geologic time, but smaller than a period
faulting
a break in a body of rock along which one block moves relative to another
folding
the bending of rock layers due to stress
fossil record
the history of life in geologic past as indicated by the traces or remains of living things
geologic time scale
a chart that divides Earth's history into different time units based on changes in the rocks and fossils
inclusion
a piece of an older rock that becomes a part of a new rock
index fossils
a fossil representation of a species that existed on Earth for a short length of time, was abundant, and inhabited many locations
Law of Superstition
principle states that younger rocks lie above older rocks if the layers have not been disturbed
period
a unit of geologic time smaller than an era
radioactive dating
the process by which an unstable element naturally changes into another element that is stable
relative age
the age of rocks and geologic features compared with other nearby rocks and features