Radiocarbon dating of rock
Results from different techniques, often measured in rival labs, continually confirm each other.Every few years, new geologic time scales are published, providing the latest dates for major time lines.Other critics, perhaps more familiar with the data, question certain aspects of the quality of the fossil record and of its dating.These skeptics do not provide scientific evidence for their views.Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data.The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them: Fossil sequences were recognized and established in their broad outlines long before Charles Darwin had even thought of evolution.
Age estimates can be cross-tested by using different isotope pairs.This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks. Some do not change with time and form stable isotopes (i.e.those that form during chemical reactions without breaking down).Early geologists, in the 1700s and 1800s, noticed how fossils seemed to occur in sequences: certain assemblages of fossils were always found below other assemblages. Since 1859, paleontologists, or fossil experts, have searched the world for fossils.In the past 150 years they have not found any fossils that Darwin would not have expected.