Radiometric dating high school
Evolution, working in tandem with geologic ages, can explain why we have index fossils, but evolution is needed to make the index fossils useful for dating strata.While we're on this subject, you might wish to know the odds of arranging the Precambrian era, the seven geologic periods of the Paleozoic (Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian), the three periods of the Mesozoic (Triassic, Jurassic, Cretaceous), and the two periods of the Cenozoic (Paleogene, Neogene or Tertiary, Quaternary) in their proper order by pure chance.One would think that the flood sediments (gathered from the four corners of the old antediluvian world) and their associated igneous rock (formed during the flood) would all register very little radiometric age.At the very least we would expect random fluctuations if the radiometric methods were totally at sea.Your chances are 6.2 billion to one of getting the right order for all thirteen.And, when you consider that each period can also be divided into "upper, middle, and lower," the odds of arranging them in the correct order by pure chance become astronomical. It has correctly placed the Cambrian between the Precambrian and the Ordovician, the Ordovician between the Cambrian and the Silurian, the Silurian between the Ordovician and the Devonian, and so forth.The depth at which either is found can vary dramatically.
(The principle of superposition was recognized as early as 1669 by Steno.) Reverend Benjamin Richardson and Reverend Joseph Townsend were a couple of early geologists involved in this work. Obviously, even Lyell was not pushing evolution at the time.Any kind of object clearly restricted to a specific point in the geologic column would do just fine.