The remarkable diversification of life, indicated by the fossil record, that occurred at the beginning of the Cambrian Period.
carbon-14 (14C) dating
A radiometric dating process that can tell us the age of organic material containing carbon originally extracted from the atmosphere.
The boundary surface between two rock bodies (as between two stratigraphic formations, between an igneous intrusion and adjacent rock, between two igneous rock bodies, or between rocks juxtaposed by a fault).
The process of defining the age relations between the strata at one locality and the strata at another.
A means of determining the relative age of rock by looking at which rock or structure cuts another; the feature that has been cut is older.
The principle that the assemblage of fossil species in a given sequence of sedimentary strata differs from that found in older sequences or in younger sequences; a given species appears at a certain level and then disappears (goes extinct) at a higher level.
A composite stratigraphic chart that represents the entirety of the Earth's history.
Different versions of a given element that have the same atomic number but different atomic weights.
The science of dating geologic events in years by measuring the ratio of parent radioactive atoms to daughter product atoms.
The age of a rock or structure as specified in years; referred to as รabsolute ageร in older literature.
The interval of geologic time between Earth's formation about 4.57 Ga and the beginning of the Phanerozoic Eon 542 Ma.
The process by which a radioactive atom undergoes fission or releases particles thereby transforming into a element.
A cross-section diagram of a sequence of strata summarizing information about the sequence.
A recognizable layer of a specific sedimentary rock type or set of rock types, deposited during a certain time interval, that can be traced over a broad region.
The principle that younger layers of sediment are deposited on older layers of sediment; thus, in a sequence of strata, the oldest layer is at the base.
A boundary between two different rock sequences representing an interval of time during which strata were not deposited and/or were eroded.