These are K-Ar data obtained on glauconite, a potassium-bearing clay mineral that forms in some marine sediment. Woodmorappe fails to mention, however, that these data were obtained as part of a controlled experiment to test, on samples of known age, the applicability of the K-Ar method to glauconite and to illite, another clay mineral. He also neglects to mention that most of the 89 K-Ar ages reported in their study agree very well with the expected ages. Evernden and others 43 found that these clay minerals are extremely susceptible to argon loss when heated even slightly, such as occurs when sedimentary rocks are deeply buried. As a result, glauconite is used for dating only with extreme caution.
How Old is the Earth
K–Ar dating - Wikipedia
Lucy and Selam's species climbed trees October 25, Australopithecus afarensis the species of the well-known "Lucy" skeleton was an upright walking species, but the question of whether it also spent much of its time in trees has been the subject of much debate, partly because The findings, published this week in the Proceedings of the National Human-like walking mechanics evolved before the genus Homo April 23, Ever since scientists realized that humans evolved from a succession of primate ancestors, the public imagination has been focused on the inflection point when those ancestors switched from ape-like shuffling to walking upright On their own 2 feet: Study shows changes in anatomy would have made walking easier without reducing muscles for climbing in early hominins April 3, An international team of researchers has found evidence that suggests evolutionary changes in anatomy would have made walking more economical without reducing utility of muscles for climbing in early hominins. A review of African fossils June 6, If "Lucy" wasn't alone, who else was in her neighborhood?
Radiometric Dating and the Geological Time Scale
Radioactive decay[ edit ] Example of a radioactive decay chain from lead Pb to lead Pb. The final decay product, lead Pb , is stable and can no longer undergo spontaneous radioactive decay. All ordinary matter is made up of combinations of chemical elements , each with its own atomic number , indicating the number of protons in the atomic nucleus.
Everything Worth Knowing About Scientific Dating Methods This dating scene is dead. The good dates are confirmed using at least two different methods, ideally involving multiple independent labs for each method to cross-check results. Sometimes only one method is possible, reducing the confidence researchers have in the results.