Radiometric dating of ordovician period
Misleading results can occur if the index fossils are incorrectly dated.
Stratigraphy and biostratigraphy can in general provide only relative dating (A was before B), which is often sufficient for studying evolution.
Strata are differentiated from each other by their different colors or compositions and are exposed in cliffs, quarries, and river banks.
Beds that preserve fossils typically lack the radioactive elements needed for radiometric dating (” radiocarbon dating ” or simply “carbon dating”).These are often characterised as the norm, rather than the exception.I thought it would be useful to present an example where the geology is simple, and unsurprisingly, the method does work well, to show the quality of data that would have to be invalidated before a major revision of the geologic time scale could be accepted by conventional scientists.For example, if fossils of B date to X million years ago and the calculated “family tree” says A was an ancestor of B, then A must have evolved earlier.It is also possible to estimate how long ago two living branches of a family tree diverged by assuming that DNA mutations accumulate at a constant rate.