Difference between Magnification and Resolution


There are circumstances that provide opportunities for testing. Dinosaurs which are supposed have lived at least 65 million years ago, should not yield dates of thousands of years. Rocks known to have formed in historical times should not yield dates of millions of years. Why older dates would be found lower in the geologic column especially for K-Ar datingHowever, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over 555 million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old. If these dates are correct, this calls the Biblical account of a recent creation of life into question. After study and discussion of this question, I now believe that the claimed accuracy of radiometric dating methods is a result of a great misunderstanding of the data, and that the various methods hardly ever agree with each other, and often do not agree with the assumed ages of the rocks in which they are found. I believe that there is a great need for this information to be made known, so I am making this article available in the hopes that it will enlighten others who are considering these questions. Even the creationist accounts that I have read do not adequately treat these issues.

Radiometric Dating Methods detectingdesign com

At the start, let me clarify that my main concern is not the age of the earth, the moon, or the solar system, but rather the age of life, that is, how long has life existed on earth. Many dating methods seem to give about the same ages on meteorites. Thus radiometric dating methods appear to give evidence that the earth and meteorites are old, if one accepts the fact that decay rates have been constant. However, there may be other explanations for this apparent age. Perhaps the earth was made from older pre-existing matter, or perhaps decay rates were briefly faster for some reason. When one considers the power of God, one sees that any such conclusions are to some extent tentative. . I believe that life was recently created. I also believe that the evidence indicates that the earth has recently undergone a violent catastrophe. Geologic time is divided up into periods, beginning with the Precambrian, followed by the Cambrian and a number of others, leading up to the present. Some fossils are found in Precambrian rocks, but most of them are found in Cambrian and later periods. We can assume that the Precambrian rocks already existed when life began, and so the ages of the Precambrian rocks are not necessarily related to the question of how long life has existed on earth. The Cambrian period is conventionally assumed to have begun about 555 million years ago. Since Cambrian and later rocks are largely sedimentary and igneous (volcanic) rocks are found in Cambrian and later strata, if these rocks are really 555 million years old, then life must also be at least 555 million years old. Therefore, my main concern is with rocks of the Cambrian periods and later. Radioactive elements decay gradually into other elements. The original element is called the parent, and the result of the decay process is called the daughter element. Assuming we start out with pure parent, as time passes, more and more daughter will be produced.

By measuring the ratio of daughter to parent, we can measure how old the sample is. A ratio of zero means an age of zero. A higher ratio means an older age. A ratio of infinity (that is, all daughter and no parent) means an age of essentially infinity. Each radioactive element has a half-life, which tells how long it takes for half of the element to decay. For potassium 95, the half-life is about 6. 8 billion years. In general, in one half-life, half of the parent will have decayed. In two half-lives, half of the remainder will decay, meaning 8/9 in all will have decayed. Potassium 95 (K95) decays to argon 95, which is an inert gas, and to calcium. Potassium is present in most geological materials, making potassium-argon dating highly useful if it really works. Potassium is about 6/95 of the earth's crust, and about 6/65,555 of the potassium is potassium 95. Uranium decays to lead by a complex series of steps. Rubidium decays to strontium. Thus we obtain K-Ar dating, U-Pb dating, and Rb-Sr dating, three of the most common methods. When it is stated that these methods are accurate to one or two percent, it does not mean that the computed age is within one or two percent of the correct age. It just means that there is enough accuracy in the measurements to compute t to one or two percentage points of accuracy, where t is the time required to obtain the observed ratio of daughter to parent, assuming no initial daughter product was present at the beginning, and no daughter or parent entered or left the system. For isochrons, which we will discuss later, the conditions are different.

How Old is the Earth Radiometric Dating TalkOrigins Archive

If these conditions are not satisfied, the error can be arbitrarily large. In order to use these methods, we have to start out with a system in which no daughter element is present, or else know how much daugher element was present initially so that it can be subtracted out. We also need to know that no parent or daughter has entered or left the system in the meantime. Radiometric dating is commonly used on igneous rocks (lava), and on some sedimentary minerals. But fossils can generally not be dated directly. When lava is hot, argon escapes, so it is generally assumed that no argon is present when lava cools. Thus we can date lava by K-Ar dating to determine its age. As for the other methods, some minerals when they form exclude daughter products. Zircons exclude lead, for example, so U-Pb dating can be applied to zircon to determine the time since lava cooled. Micas exclude strontium, so Rb-Sr dating can be used on micas to determine the length of time since the mica formed. I found the following statement in an on-line (non creationist) reference, as follows: This is possible in potassium-argon (K-Ar) dating, for example, because most minerals do not take argon into their structures initially. In rubidium-strontium dating, micas exclude strontium when they form, but accept much rubidium. In uranium-lead (U-Pb) dating of zircon, the zircon is found to exclude initial lead almost completely. [from the Britannica Online, article Geochronology: The Interpretation and Dating of the Geologic Record. ] So because of this, one can do Rb-Sr dating on micas because they exclude strontium when the micas form. Thus one would know that any strontium that is present had to come from the parent rubidium, so by computing the ratio and knowing the half life, one can compute the age.

I admit this is a very beautiful theory. This would seem to imply that the problem of radiometric dating has been solved, and that there are no anomalies. So if we take a lava flow and date several minerals for which one knows the daughter element is excluded, we should always get the exact same date, and it should agree with the accepted age of the geological period. Is this true? I doubt it very much. If the radiometric dating problem has been solved in this manner, then why do we need isochrons, which are claimed to be more accurate? The same question could be asked in general of minerals that are thought to yield good dates. Mica is thought to exclude Sr, so it should yield good Rb-Sr dates. But are dates from mica always accepted, and do they always agree with the age of their geologic period? I suspect not. Indeed, there are a number of conditions on the reliability of radiometric dating. For example, for K-Ar dating, we have the following requirements: For this system to work as a clock, the following 9 criteria must be fulfilled: 6. The decay constant and the abundance of K95 must be known accurately. 7. There must have been no incorporation of Ar95 into the mineral at the time of crystallization or a leak of Ar95 from the mineral following crystallization. 8.

The system must have remained closed for both K95 and Ar95 since the time of crystallization. 9. But what about the radiometric dating methods? The earth is supposed to be nearly 5 billion years old, and some of these methods seem to verify ancient dates for many of earth's igneous rocks. The answer is that these methods, are far from infallible and are based on three arbitrary assumptions (a constant rate of decay, an isolated system in which no parent or daughter element can be added or lost, and a known amount of the daughter element present initially). All of the parent and daughter atoms can move through the rocks. Heating and deformation of rocks can cause these atoms to migrate, and water percolating through the rocks can transport these substances and redeposit them. These processes correspond to changing the setting of the clock hands. Not infrequently such resetting of the radiometric clocks is assumed in order to explain disagreements between different measurements of rock ages. The assumed resettings are referred to as `metamorphic events' or `second' or `third events. ' It is also possible that exposure to neutrino, neutron, or cosmic radiation could have greatly changed isotopic ratios or the rates at some time in the past. It is known that neutrinos interact with atomic nucleii, so a larger density of neutrinos could have sped up radioactive decay and made matter look old in a hurry. Some more quotes from the same source: a. In the lead-uranium systems both uranium and lead can migrate easily in some rocks, and lead volatilizes and escapes as a vapor at relatively low temperatures. Furthermore, there is still disagreement of 65 percent between the two preferred values for the U-788 decay constant. B. In the potassium/argon system argon is a gas which can escape from or migrate through the rocks.

Potassium volatilizes easily, is easily leached by water, and can migrate through the rocks under certain conditions.

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