Carbon, Radiometric Dating - CSI
Geologists do not use carbon-based radiometric dating to determine the age of rocks. Carbon dating only works for objects that are younger. earth's history, carbon dating,dinosaurs,fossils,dinosaur bone dates. Yet, when carbon-containing rocks or bones are tested they always contain c Understanding how scientists date rocks and the age of the earth. 3. Scientific State/write the underlying assumption in the carbon dating method and how.
Typically commonly occurring fossils that had a widespread geographic distribution such as brachiopods, trilobites, and ammonites work best as index fossils. If the fossil you are trying to date occurs alongside one of these index fossils, then the fossil you are dating must fall into the age range of the index fossil.
Sometimes multiple index fossils can be used. In a hypothetical example, a rock formation contains fossils of a type of brachiopod known to occur between and million years.
The same rock formation also contains a type of trilobite that was known to live to million years ago. Since the rock formation contains both types of fossils the ago of the rock formation must be in the overlapping date range of to million years. Studying the layers of rock or strata can also be useful. Layers of rock are deposited sequentially.
If a layer of rock containing the fossil is higher up in the sequence that another layer, you know that layer must be younger in age.
This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks. Absolute Dating Absolute dating is used to determine a precise age of a rock or fossil through radiometric dating methods. This uses radioactive minerals that occur in rocks and fossils almost like a geological clock. So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks.
The atoms in some chemical elements have different forms, called isotopes.
18.5D: Carbon Dating and Estimating Fossil Age
These isotopes break down at a constant rate over time through radioactive decay. By measuring the ratio of the amount of the original parent isotope to the amount of the daughter isotopes that it breaks down into an age can be determined. We define the rate of this radioactive decay in half-lives. 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.
- How do geologists use carbon dating to find the age of rocks?
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.
Dating Fossils – How Are Fossils Dated?
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. 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. 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.
Dating Fossils – How Are Fossils Dated? - stelmaschuk.info
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. As the magma chamber is depleted in daughter products, subsequent lava flows and ash beds would have younger dates. It does suggest at least one aspect of the problem that could be researched more thoroughly. The problems inherent in radiometric dating often cause them to be so unreliable that they contradict one another rather than validating each other.