Radiometric dating of rocks and fossils

Carbon, Radiometric Dating and Index Fossils - Creation Studies Institute

radiometric dating of rocks and fossils

Dating in geology may be relative or absolute. Relative dating is done by observing fossils, as described above, and recording which fossil is younger, which is. All of these methods measure the amount of radioactive decay of chemical (like DNA) decays rapidly, the molecular clock method can't date very old fossils. The short half-life of carbon means it cannot be used to date fossils that are . All radiometric dating methods use this basic principle to extrapolate the age of.

radiometric dating of rocks and fossils

Also, many fossils are contaminated with carbon from the environment during collection or preservation procedures. Scientists attempt to check the accuracy of carbon dating by comparing carbon dating data to data from other dating methods. Other methods scientists use include counting rock layers and tree rings.

radiometric dating of rocks and fossils

When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age. Scientists now realize that production of carbon has not been constant over the years, but has changed as the radiation from the sun has fluctuated.

Nuclear tests, nuclear reactors and the use of nuclear weapons have also changed the composition of radioisotopes in the air over the last few decades. This human nuclear activity will make precise dating of fossils from our lifetime very difficult due to contamination of the normal radioisotope composition of the earth with addition artificially produced radioactive atoms.

The various confounding factors that can adversely affect the accuracy of carbon dating methods are evident in many of the other radioisotope dating methods.

Although the half-life of some of them are more consistent with the evolutionary worldview of millions to billions of years, the assumptions used in radiometric dating put the results of all radiometric dating methods in doubt.

The following is an article on this subject. These isotopes have longer half-lives and so are found in greater abundance in older fossils. Some of these other isotopes include: The assumptions are similar to the assumptions used in carbon dating. The mathematical premise undergirding the use of these elements in radiometric dating contains the similar confounding factors that we find in carbon dating method. Most scientists today believe that life has existed on the earth for billions of years.

This belief in long ages for the earth and the evolution of all life is based entirely on the hypothetical and non-empirical Theory of Evolution. All dating methods that support this theory are embraced, while any evidence to the contrary, e. Prior to radiometric dating, evolution scientists used index fossils a. A paleontologist would take the discovered fossil to a geologist who would ask the paleontologist what other fossils searching for an index fossil were found near their discovery.

If it sounds like circular reasoning, it is because this process in reality is based upon circular reasoning. Henry Morris as follows: These long time periods are computed by measuring the ratio of daughter to parent substance in a rock, and inferring an age based on this ratio. This age is computed under the assumption that the parent substance say, uranium gradually decays to the daughter substance say, leadso the higher the ratio of lead to uranium, the older the rock must be.

While there are many problems with such dating methods, such as parent or daughter substances entering or leaving the rock, e.

radiometric dating of rocks and fossils

Geologists assert that generally speaking, older dates are found deeper down in the geologic column, which they take as evidence that radiometric dating is giving true ages, since it is apparent that rocks that are deeper must be older. But even if it is true that older radiometric dates are found lower down in the geologic column which is open to questionthis can potentially be explained by processes occurring in magma chambers which cause the lava erupting earlier to appear older than the lava erupting later.

Lava erupting earlier would come from the top of the magma chamber, and lava erupting later would come from lower down. A number of processes could cause the parent substance to be depleted at the top of the magma chamber, or the daughter product to be enriched, both of which would cause the lava erupting earlier to appear very old according to radiometric dating, and lava erupting later to appear younger.

Other possible confounding variables are the mechanisms that can alter daughter-to-parent ratios.

Accuracy of Fossils and Dating Methods

We can see that many varieties of minerals are produced from the same magma by the different processes of crystallization, and these different minerals may have very different compositions. It is possible that the ratio of daughter to parent substances for radiometric dating could differ in the different minerals.

Clearly, it is important to have a good understanding of these processes in order to evaluate the reliability of radiometric dating.

radiometric dating of rocks and fossils

Other confounding factors such as contamination and fractionation issues are frankly acknowledged by the geologic community, but are not taken into consideration when the accuracy and validity of these dating methods are examined. The following quotation from Elaine G. Kennedy addresses this problem. Contamination and fractionation issues are frankly acknowledged by the geologic community.

For example, if a magma chamber does not have homogeneously mixed isotopes, lighter daughter products could accumulate in the upper portion of the chamber. If this occurs, initial volcanic eruptions would have a preponderance of daughter products relative to the parent isotopes. Such a distribution would give the appearance of age.

Stratigraphy, the study of rock layers, led to paleontology, the study of fossils. Then, geologists began to build up the stratigraphic column, the familiar listing of divisions of geological time — Jurassic, Cretaceous, Tertiary, and so on.

Each time unit was characterized by particular fossils. The scheme worked all round the world, without fail. From the s onwards, geologists noted how fossils became more complex through time. The oldest rocks contained no fossils, then came simple sea creatures, then more complex ones like fishes, then came life on land, then reptiles, then mammals, and finally humans. Accuracy of the fossils Fossils prove that humans did not exist alongside dinosaurs.

Sincepaleontologists, or fossil experts, have searched the world for fossils. In the past years they have not found any fossils that Darwin would not have expected. Darwin and his contemporaries could never have imagined the improvements in resolution of stratigraphy that have come sincenor guessed what fossils were to be found in the southern continents, nor predicted the huge increase in the number of amateur and professional paleontologists worldwide.

All these labors have not led to a single unexpected finding such as a human fossil from the time of the dinosaurs, or a Jurassic dinosaur in the same rocks as Silurian trilobites. Scientists now use phylogeny, mathematics, and other computations to date fossils.

ActionBioscience - promoting bioscience literacy

Paleontologists now apply sophisticated mathematical techniques to assess the relative quality of particular fossil successions, as well as the entire fossil record. These demonstrate that, of course, we do not know everything and clearly never willbut we know enough. Today, innovative techniques provide further confirmation and understanding of the history of life.

Biologists actually have at their disposal several independent ways of looking at the history of life - not only from the order of fossils in the rocks, but also through phylogenetic trees. Phylogenetic trees are the family trees of particular groups of plants or animals, showing how all the species relate to each other. Phylogenetic trees are drawn up mathematically, using lists of morphological external form or molecular gene sequence characters. Modern phylogenetic trees have no input from stratigraphy, so they can be used in a broad way to make comparisons between tree shape and stratigraphy.

The majority of test cases show good agreement, so the fossil record tells the same story as the molecules enclosed in living organisms. Accuracy of dating Dating in geology may be relative or absolute.

Dating | The Smithsonian Institution's Human Origins Program

Relative dating is done by observing fossils, as described above, and recording which fossil is younger, which is older. The discovery of means for absolute dating in the early s was a huge advance.

The methods are all based on radioactive decay: Fossils may be dated by calculating the rate of decay of certain elements.

How Do Paleontologists Date Fossils? - Secrets of the Underground

Certain naturally occurring elements are radioactive, and they decay, or break down, at predictable rates. Chemists measure the half-life of such elements, i. Sometimes, one isotope, or naturally occurring form, of an element decays into another, more stable form of the same element.

By comparing the proportions of parent to daughter element in a rock sample, and knowing the half-life, the age can be calculated. Older fossils cannot be dated by carbon methods and require radiometric dating. Scientists can use different chemicals for absolute dating: The best-known absolute dating technique is carbon dating, which archaeologists prefer to use.

However, the half-life of carbon is only years, so the method cannot be used for materials older than about 70, years. Subtle differences in the relative proportions of the two isotopes can give good dates for rocks of any age. Scientists can check their accuracy by using different isotopes. The first radiometric dates, generated aboutshowed that the Earth was hundreds of millions, or billions, of years old. Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates.

Age estimates can be cross-tested by using different isotope pairs. Results from different techniques, often measured in rival labs, continually confirm each other.