Radiocarbon datingalso called carbon dating, uses the unstable isotope carbon 14 C and the stable isotope carbon 12 C. The wavy rock is a old metamorphic gneiss, A and F are faults, B is an igneous granite, D is a basaltic dike, and C and E are sedimentary strata. This is common in uranium-bearing mineral grains such as apatite. Fission track dating has also been used as a second clock to confirm dates obtained by other methods. Another radioisotopic dating method involves carbon and is useful for dating archaeologically important samples containing organic substances like wood or bone. Foraminifera, microscopic creatures with hard shells.
Relative dating is used to arrange geological events, and the rocks they leave behind, in a sequence.
7 Geologic Time
Burrows dug by tunneling organisms tell of their presence and mode of life. The British naturalist Charles Darwin recognized that life forms evolve into progeny life forms. Simulation of half-life. Dinosaur tracks testify to their presence and movement over an area, and even provide information about their size, gait, speed, and behavior. Index fossils used for biostratigraphic correlation. Up to that point ammonoids were the only standard for Triassic correlationso cross-referencing micro- and macro- index fossils enhanced the reliability of biostratigraphic correlation for either type.