Radiometric dating is often used to “prove” rocks are millions of years old. Once you understand the basic science, however, you can see how wrong assumptions lead to incorrect dates.
Most people think that radioactive dating has proven the earth is billions of years old. Yet this view is based on a misunderstanding of how radiometric dating works. Part 1 (in the previous issue) explained how scientists observe unstable atoms changing into stable atoms in the present. Part 2 explains how scientists run into problems when they make assumptions about what happened in the unobserved past.
The Hourglass “Clock”—An Analogy for Dating Rocks
An hourglass is a helpful analogy to explain how geologists calculate the ages of rocks. When we look at sand in an hourglass, we can estimate how much time has passed based on the amount of sand that has fallen to the bottom.
The reliability of radiometric dating is subject to three unprovable assumptions that every geologist must make when using the radioactive “clock”.
Radioactive rocks offer a similar “clock.” Radioactive atoms, such as uranium (the parent isotopes), decay into stable atoms, such as lead (the daughter isotopes), at a measurable rate. To date a radioactive rock, geologists first measure the “sand grains” in the top glass bowl (the parent radioisotope, such as uranium-238 or potassium-40).
They also measure the sand grains in the bottom bowl (the daughter isotope, such as lead-206 or argon-40, respectively). Based on these observations and the known rate of radioactive decay, they estimate the time it has taken for the daughter isotope to accumulate in the rock.
However, unlike the hourglass whose accuracy can be tested by turning it upside down and comparing it to trustworthy clocks, the reliability of the radioactive “clock” is subject to three unprovable assumptions. No geologist was present when the rocks were formed to see their contents, and no geologist was present to measure how fast the radioactive “clock” has been running through the millions of years that supposedly passed after the rock was formed.
Assumption 1: Conditions at Time Zero
No geologists were present when most rocks formed, so they cannot test whether the original rocks already contained daughter isotopes alongside their parent radioisotopes. For example, with regard to the volcanic lavas that erupted, flowed, and cooled to form rocks in the unobserved past, evolutionary geologists simply assume that none of the daughter argon-40 atoms was in the lava rocks.
For the other radioactive “clocks,” it is assumed that by analyzing multiple samples of a rock body, or unit, today it is possible to determine how much of the daughter isotopes (lead, strontium, or neodymium) were present when the rock formed (via the so-called isochron technique, which is still based on unproven assumptions 2 and 3).
Yet lava flows that have occurred in the present have been tested soon after they erupted, and they invariably contained much more argon-40 than expected.1 For example, when a sample of the lava in the Mt. St. Helens crater (that had been observed to form and cool in 1986) (Figure 1) was analyzed in 1996, it contained so much argon-40 that it had a calculated “age” of 350,000 years!2 Similarly, lava flows on the sides of Mt. Ngauruhoe, New Zealand (Figure 2), known to be less than 50 years old, yielded “ages” of up to 3.5 million years.3
So it is logical to conclude that if recent lava flows of known age yield incorrect old potassium-argon ages due to the extra argon-40 that they inherited from the erupting volcanoes, then ancient lava flows of unknown ages could likewise have inherited extra argon-40 and yield excessively old ages.
There are similar problems with the other radioactive “clocks.” For example, consider the dating of Grand Canyon’s basalts (rocks formed by lava cooling at the earth’s surface). We find places on the North Rim where volcanoes erupted after the Canyon was formed, sending lavas cascading over the walls and down into the Canyon.
Obviously, these eruptions took place very recently, after the Canyon’s layers were deposited (Figure 3). These basalts yield ages of up to 1 million years based on the amounts of potassium and argon isotopes in the rocks. But when we date the rocks using the rubidium and strontium isotopes, we get an age of 1.143 billion years. This is the same age that we get for the basalt layers deep below the walls of the eastern Grand Canyon.4
How could both lavas—one at the top and one at the bottom of the Canyon—be the same age based on these parent and daughter isotopes? One solution is that both the recent and early lava flows inherited the same rubidium-strontium chemistry—not age—from the same source, deep in the earth’s upper mantle. This source already had both rubidium and strontium.
To make matters even worse for the claimed reliability of these radiometric dating methods, these same basalts that flowed from the top of the Canyon yield a samarium-neodymium age of about 916 million years,5 and a uranium-lead age of about 2.6 billion years!6
Assumption 2: No Contamination
The problems with contamination, as with inheritance, are already well-documented in the textbooks on radioactive dating of rocks.7 Unlike the hourglass, where its two bowls are sealed, the radioactive “clock” in rocks is open to contamination by gain or loss of parent or daughter isotopes because of waters flowing in the ground from rainfall and from the molten rocks beneath volcanoes. Similarly, as molten lava rises through a conduit from deep inside the earth to be erupted through a volcano, pieces of the conduit wallrocks and their isotopes can mix into the lava and contaminate it.
Because of such contamination, the less than 50-year-old lava flows at Mt. Ngauruhoe, New Zealand (Figure 4), yield a rubidium-strontium “age” of 133 million years, a samarium-neodymium “age” of 197 million years, and a uranium-lead “age” of 3.908 billion years!8
Assumption 3: Constant Decay Rate
Physicists have carefully measured the radioactive decay rates of parent radioisotopes in laboratories over the last 100 or so years and have found them to be essentially constant (within the measurement error margins). Furthermore, they have not been able to significantly change these decay rates by heat, pressure, or electrical and magnetic fields. So geologists have assumed these radioactive decay rates have been constant for billions of years.
However, this is an enormous extrapolation of seven orders of magnitude back through immense spans of unobserved time without any concrete proof that such an extrapolation is credible. Nevertheless, geologists insist the radioactive decay rates have always been constant, because it makes these radioactive clocks “work”!
New evidence, however, has recently been discovered that can only be explained by the radioactive decay rates not having been constant in the past.9 For example, the radioactive decay of uranium in tiny crystals in a New Mexico granite (Figure 5) yields a uranium-lead “age” of 1.5 billion years. Yet the same uranium decay also produced abundant helium, but only 6,000 years worth of that helium was found to have leaked out of the tiny crystals.
This means that the uranium must have decayed very rapidly over the same 6,000 years that the helium was leaking. The rate of uranium decay must have been at least 250,000 times faster than today’s measured rate! For more details see Don DeYoung’s Thousands . . . Not Billions (Master Books, Green Forest, Arkansas, 2005), pages 65–78.
If these clocks are based on faulty assumptions and yield unreliable results, then scientists should not trust or promote the claimed radioactive “ages.”
The assumptions on which the radioactive dating is based are not only unprovable but plagued with problems. As this article has illustrated, rocks may have inherited parent and daughter isotopes from their sources, or they may have been contaminated when they moved through other rocks to their current locations. Or inflowing water may have mixed isotopes into the rocks. In addition, the radioactive decay rates have not been constant.
So if these clocks are based on faulty assumptions and yield unreliable results, then scientists should not trust or promote the claimed radioactive “ages” of countless millions of years, especially since they contradict the true history of the universe as recorded in God’s Word.
Previous Article BonesNextArticle Creation on Display
October – December 2009
When it comes to God’s marvelous creation, nothing compares to the amazing design of the human body. From the protective garment of skin to the engineering of our bones and new discoveries about our brain, this issue is packed with testimony to the Master Designer.Browse IssueSubscribe
Most scientists and many Christians believe that the radiometric dating methods prove that the earth is 4.5 billion years old. Recent research shows otherwise.
Knowing this first: that scoffers will come in the last days, walking according to their own lusts, and saying, “Where is the promise of His coming? For since the fathers fell asleep, all things continue as they were from the beginning of creation.” For this they willfully forget: that by the word of God the heavens were of old, and the earth standing out of water and in the water, by which the world that then existed perished, being flooded with water.
—2 Peter 3:3–6
What You Will Learn
Most scientists and many Christians believe that the radiometric dating methods prove that the earth is 4.5 billion years old. The textbooks speak of the radiometric dating techniques, and the dates themselves, as factual information. Far from being data, these dates are actually interpretations of the data. As discussed before, the assumptions influence the interpretation of the data. There are three main assumptions that must be made to accept radiometric dating methods. These must be accepted on faith in uniformitarian and naturalistic frameworks.
Recent research by a team of creation scientists known as the RATE (Radioisotopes and the Age of The Earth) group has demonstrated the unreliability of radiometric dating techniques. Even the use of isochron dating, which is supposed to eliminate some initial condition assumptions, produces dates that are not reliable. Despite the fact that there are many scientific problems with radiometric dating, there is a more significant problem. The Bible gives a much different picture and explains that relying on man’s reasoning is foolishness. A fear of God and reverence for His Word is the beginning of wisdom. Starting with the Bible and developing a model for dating events in earth history will lead us to the truth. The Bible gives us a much more reliable history of the earth as it was recorded by God.
What Your Textbook Says about Dating Methods
What We Really Know about Dating Methods
When someone mentions scientific dating methods, the first thing to come to mind for most people is carbon dating. However, there are many methods that can be used to determine the age of the earth or other objects. The textbooks focus on relative dating, based on the layering of the rocks, and radiometric dating.
Relative ages are assigned to rocks based on the idea that rock layers lower in the strata were deposited before rock layers that are higher. Creationists do not necessarily disagree with this concept, but it can only be applied to layers that are found in one location and/or can be determined to have been deposited in a continuous layer over a very wide area. There is also a difference in the timescale used to explain the layers. Determining the relative age of a rock layer is based on the assumption that you know the ages of the rocks surrounding it. Uniformitarian geologists use so-called absolute dating methods to determine the ages of the surrounding rocks.
Certain types of rocks, especially those that form from magma (igneous), contain radioactive isotopes of different elements. It is possible to measure the ratio of the different radioactive parent isotopes and their daughter isotopes in a rock, but the ratios are not dates or ages. The dates must be inferred based on assumptions about the ratios. Some of the common isotope pairs used are K-Ar, Rb-Sr, Pb-Pb, and U-Pb.
- Radiometric Dating
- Using ratios of isotopes produced in radioactive decay to calculate an age of the specimen based on assumed rates of decay and other assumptions.
Carbon-14 dating is another common technique, but it can only be used on carbon-containing things that were once alive. The method of calculating radiometric dates is like using an hourglass. You can use the hourglass to tell time if you know several things: the amount of sand in the top of the hourglass when it started flowing, the rate that the sand flows through the hole in the middle, and that the quantity of sand in each chamber has not been tampered with. If any of these three conditions is not accurately known, the hourglass will give an inaccurate measure of time.
Radiometric dating is based on the fact that radioactive isotopes decay to form isotopes of different elements. The starting isotope is called the parent and the end-product is called the daughter. The time it takes for one half of the parent atoms to decay to the daughter atoms is called the half-life. If certain things are known, it is possible to calculate the amount of time since the parent isotope began to decay. For example, if you began with 1 gram of carbon-14, after 5,730 years you would be left with 0.50 g and only 0.25 g after 11,460 years. The reason this age may not be a true age—even though it is commonly called an absolute age—is that it is based on several crucial assumptions. Most radiometric dating techniques must make three assumptions:
- The rate of radioactive decay is known and has been constant since the rock formed.
- There has been no loss or gain of the parent or daughter isotopes from the rock.
- The amounts of parent and daughter isotopes present when the rock formed are known.
The major problem with the first assumption is that there is no way to prove that the decay rate was not different at some point in the past. The claimed “fact” that decay rates have always been constant is actually an inference based on a uniformitarian assumption. It is true that radioisotope decay rates are stable today and are not largely affected by external conditions like change in temperature and pressure, but that does not mean that the rate has always been constant.
Recent research by a creation science group known as RATE (Radioisotopes and the Age of The Earth) has produced evidence of accelerated rates of decay at some point (or points) in the past. Creation scientists suggest that there are two possible times that God supernaturally intervened on a global scale—during Creation Week and the Flood. It is not unreasonable to assume that God used the energy of accelerated radioactive decay to initiate and drive the major geologic changes in the earth that accompanied the Flood.
Evidence for the period of accelerated decay is found in zircon crystals. Zircon crystals in granite contain radioactive uranium-238, which decays into lead over time. As the uranium decays, helium is produced in the crystals. Helium escapes from the crystals at a known, measurable rate. If those rocks were over a billion years old, as evolutionists claim, the helium should have leaked out of the rock. The presence of lots of helium in the crystals is evidence in support of a young earth.
Other important findings of the RATE project include detecting carbon-14 in coal and diamonds. If these substances were really millions or billions of years old respectively, there should be no carbon-14 left in them. Carbon-14 has a half-life of 5,730 years. With the most accurate mass spectrometers, the oldest calculated age of items containing carbon-14 is about 80,000 years. Diamonds are assumed to be many billions of years old and should contain no detectable carbon-14 as it would have all decayed to nitrogen-14 long ago. The same is true of coal which was supposedly deposited hundreds of millions of years ago, according to the evolutionary model. The presence of carbon-14 in these materials clearly supports the idea of a young earth as described by the Bible.
The assumption that there has been no loss or gain of the isotopes in the rock (assumption 2) does not take into account the impact of weathering by surface and ground waters and the diffusion of gases. It is impossible to know to what degree the parent and daughter products have been added to or removed from the rocks over the alleged millions or billions of years.
The final assumption (assumption 3) does not take into account the fact that isotopes can be inherited from the source areas of magmas and/or from surrounding rocks as the magmas pass through the mantle and crust of the earth. Uniformitarian geologists do make efforts to eliminate errors, but the fact that rocks of known recent age give dates of millions, and even billions, of years supports the claim that radiometric dating cannot provide accurate “absolute” dates. Also, samples taken a few feet apart can give ages that differ by many hundreds of millions of years.
Many people do not realize that fossils themselves are usually not directly dated. Instead, layers that contain datable igneous rocks above or below a fossil-bearing layer are used to estimate the age of the fossil. The age of the fossil can be estimated within the range of the layers above and below it. In some cases, the ages are correlated to other rock layers of supposedly known age or by using index fossils. These methods assume that the distribution of index fossils and the correlation of strata are well understood on a global scale.
Another finding of the RATE team is very intriguing. The team took samples of diabase, an igneous rock, and tested them using various radiometric dating techniques. If the dating methods are all objective and reliable, then they should give similar dates. The rocks were tested as whole-rock samples using K-Ar dating and also separated into individual minerals. The whole-rock and separated mineral samples allow a method known as isochron dating to be done. This method is supposed to eliminate the assumption that the initial concentration of the daughter element is zero.
Despite removing this assumption, the RATE team has shown that this method is not reliable. Dating the Cardenas Basalt, a layer near the bottom of Grand Canyon, and a volcanic layer from near the top of Grand Canyon produced an amazing result. Based on the law of superposition, the lower layers in the canyon should be older than the upper layers (unless there was an intrusion or other event that changed the order). Using isochron dating from a respected lab, the lower rocks were dated at 1.07 billion years and the upper, and presumably younger rocks, were dated at 1.34 billion years. There is an obvious discordance (disagreement) in the data. So the question becomes, “Can we trust the dates given in the textbooks if the techniques are not objective?” (More information on the RATE research can be found in article 4:3.)
Because these dates are based on methods with multiple assumptions, and are contrary to the Bible, we must reject that they are accurate. Despite the fact that a majority of scientists and even many theologians accept the dates, God’s Word must be our ultimate authority.
There are many other methods that can be used to establish ages for parts of the earth and the solar system. These methods will be discussed in the following chapter. Regardless of what method we use, we must start with assumptions and interpret the facts accordingly. Understanding what those assumptions are is important. If we are not aware of the assumptions that are being used, we can easily be deceived. We should always start with the Bible, the ultimate source of truth.
When we try to use man’s ideas and assumptions to understand nature, we are forgetting that Proverbs 2:1–6 tells us:
My son, if you receive my words, and treasure my commands within you,
So that you incline your ear to wisdom, and apply your heart to understanding;
Yes, if you cry out for discernment, and lift up your voice for understanding,
If you seek her as silver, and search for her as for hidden treasures;
Then you will understand the fear of the Lord, and find the knowledge of God.
Reference Article Summaries
4:1 Does radiometric dating prove the earth is old?
Proponents of evolution suggest that radiometric dating has proven that the earth is between 4.5 and 4.6 billion years old. But what is this age based on? A straightforward reading of the Bible shows that the earth was created in six days about 6,000 years ago. Radiometric dating uses ratios of isotopes in rocks to infer the age of the rock.
Scientists use a mix of observational data and assumptions about the past to determine the radiometric age of a rock. Comparing the amount of a parent isotope to the amount of its daughter isotope and knowing the rate of change from parent into daughter (known as the half-life), the age of the rock can be determined. However, there are several assumptions that must be made in this process.
The three critical assumptions are:
- The initial conditions of the rock sample are accurately known.
- The amount of parent or daughter elements in a sample has not been altered by processes other than radioactive decay.
- The decay rate (or half–life) of the parent isotope has remained constant since the rock was formed.
An hourglass can be used as an analogy to explain the assumptions. An hourglass can be used to tell time only if we know how much sand was in each chamber at the beginning, that there was no sand added or removed from either chamber, and that the sand falls at a constant rate. If any of these factors is not known, the time given may not be accurate. The same goes for the dating of rocks using radioisotopes. Assumption 1 was proven false when scientists from the RATE group had rocks of known age dated. These rocks were dated at up to 3.5 million years old when none of them were older than 70 years. How can we trust this method to tell us the age of rocks when the data do not match with observations?
Isochron dating is supposed to remove the assumption of initial conditions, but some different assumptions are necessary. If radiometric dating techniques are objective and accurate, then comparing the single–sample dates to the isochron dates should give similar results. In the RATE report there were dates that differed by up to a billion years. One volcanic rock layer from the top of Grand Canyon was dated 270 million years older than the oldest rocks below it near the bottom of the canyon.
Other case studies by the RATE group show dates that vary greatly depending on the sample and dating technique used. The most reasonable explanation seems to be that the rates of decay have been different at some point in the past. This is supported by the presence of large amounts of helium in some minerals. If there had been more than a billion years since the rocks had formed, the helium should have leaked out of the rocks by now. The presence of helium seems to support the recent accelerated decay of the isotopes, leaving a large amount of helium trapped in the rocks.
The Bible presents a very different picture of the age of the earth when compared to radiometric dating using evolutionary assumptions. It is better to use the infallible Word of God for our scientific assumptions than to compromise it with man’s ideas.
4:2 Doesn’t carbon-14 dating disprove the Bible?
Radiometric dating is a technique that uses the change of one isotope, the parent, to another, the daughter, to determine the amount of time since the decay began. Carbon-14 is supposed to allow dating of objects up to 60,000 years. If these dates were true, they would seem to discredit the biblical account of a young earth of about 6,000 years.
Since the Bible is the inspired Word of God, we should examine the validity of the standard interpretation of carbon-14 dating by asking several questions:
- Is the explanation of the data derived from empirical, observational science, or an interpretation of past events (historical science)?
- Are there any assumptions involved in the dating method?
- Are the dates provided by carbon-14 dating consistent with what we observe?
- Do all scientists accept the carbon-14 dating method as reliable and accurate?
Carbon-14 dating is used to date things that were once living. The unstable carbon-14 decays to stable nitrogen-14 as one of its neutrons is converted to a proton through beta decay. Carbon-14 is constantly supplied as high energy neutrons collide with nitrogen-14 in the upper atmosphere. This carbon-14 combines with oxygen to form carbon dioxide and is taken in by plants and then animals. Each living thing should have roughly the same ratio of radioactive carbon-14 to normal carbon-12.
When an organism dies, it no longer takes in carbon-14, and the decay process begins. Assuming that the rate of decay and the starting amount of carbon-14 is known, this decay process can be used as a clock. However, the ratio of carbon isotopes is not constant and can be affected by the earth’s magnetic field strength and the amount of plant and animal matter in the biosphere. The plants and animals buried in the recent Flood could account for a large change in the ratios and demonstrate the false assumption of carbon equilibrium.
The RATE group has also documented carbon-14 in coal and diamonds that are supposed to be millions to billions of years old. If these items were truly more than 100,000 years old, there should be no detectable carbon-14 present in them. These findings point to the age of the earth being much younger than evolutionary scientists would suggest.
4:3 Radioisotopes and the age of the earth
A long-term research project involving several creation scientists has produced intriguing new evidence in support of an earth that is thousands of years old rather than many billions. Some of the findings are summarized below.
The presence of fission tracks and radiohalos in crystals demonstrates that hundreds of millions of years worth of radioactive decay has occurred in a very short period. Because the Bible indicates the earth is young (about 6,000 years old), this large quantity of nuclear decay must have occurred at much faster rates than those measured today.
Using various radiometric dating methods to measure the ages of rock samples consistently produced ages that varied greatly. This may be explained by the different parent atoms having decayed at different rates in the past—an explanation not allowed by evolutionists. These changes in decay rates could be accounted for by very small changes in the binding forces within the nuclei of the parent atoms.
Research has been done to demonstrate that many of the assumptions used in radiometric dating are false. Starting from biblical assumptions regarding the Flood and Creation can provide a new framework for interpreting current scientific data.
4:4 Tree rings and biblical chronology
Bristlecone pines are the oldest living things on the earth. Native to the mountains of California and Nevada, the oldest tree has been dated at 4,600 years old. By correlating the rings with dead wood found near the trees and beams from local buildings, a chronology of 11,300 rings has been suggested. However, this does not necessarily correlate to years because multiple rings can grow in one year.
The 4,600 year age of the oldest tree, named Methuselah, corresponds to the date of the Flood given by Ussher and others. If Methuselah began growing shortly after the Flood, then it stands as a record that confirms the Bible.
4:5 Are there half a million years in the sediments of Lake Van?
Lake Van is a salt lake in Turkey that uniformitarian scientists believe holds a record of the last 800,000 years of the earth’s climate. The layers of sediment are up to 400 meters thick and were supposedly laid down one layer at a time each year. Evolutionists assume the layers, called varves, roughly correspond to years based on assumptions about present processes.
Varves are also used to date other lakes around the world to the time of the last ice age—supposedly 10,000 years ago. Many other alleged varve deposits challenge the biblical timescale and must be reinterpreted within the creationist framework. The repeating layers should be referred to as rhythmites and simply represent successive deposits over time. These different layers can be deposited as particles of different size and density settle out of flowing water. Studies at Lake Walensee, Switzerland, showed over 300 layers forming in 160 years. Different areas had different patterns and were not able to be correlated directly.
Other studies have shown multiple layers forming as the result of light rainfall, increasing river flow, and increased snowmelt. Underwater turbidity currents are often interpreted as varves, but they form many layers rapidly. It is common, therefore, for multiple layers to form in a single year.
All of these layers can be explained within the Flood model as catastrophic melting and drainage events deposited many layers over a short period of time during localized residual catastrophism in the immediate aftermath of the Flood. Uniformitarian geologists assume the slow rate of deposition as observed today for the past. However, in many cases they really have not observed the present sedimentation rate, and in some cases where they have used sediment traps, not all the deposition has been recorded. Creationists, on the other hand, can postulate much higher rates in the past due to the Flood, localized residual post-Flood catastrophism, and/or a rapid post-Flood Ice Age—the rate tapering off to the present slow rate.
Questions to Consider
- Do radiometric dating techniques always show that rocks lower in the geologic layers are older than rocks that are higher?
- If radiometric dating on rocks known to be only a few years old yields dates of millions of years, why should we trust that the techniques can be used to accurately date rocks of unknown ages?
- In radiometric dating techniques, how do we know how much parent material the sample started with? How do we know none of the parent or daughter isotope was added or removed? How do we know the decay rate is constant?
- When items are carbon-14 dated, how do we know how much carbon-14 was initially present in the sample? Could the ratio of carbon-14 to carbon-12 have been different at different times in earth’s history? How can scientists accurately adjust their calculations if the isotope ratios were never observed and recorded?
- What assumptions are involved in radiometric dating?
Tools for Digging Deeper
Evolution: The Fossils Still Say No! by Duane Gish
The Geology Book by John Morris
The New Answers Book by Ken Ham et al.
The New Answers Book 2 by Ken Ham et al.
Radioisotopes and the Age of the Earth Volume 1 (Technical) by ICR
Radioisotopes and the Age of the Earth Volume 2 (Technical) by ICR
Thousands . . . Not Billions by Don DeYoung
Previous Chapter Origin of the Solar SystemNextChapter Age of the Solar System
Evolution Exposed: Earth Science
In this follow-up to the best-selling Evolution Exposed: Biology, students will learn how to respectfully counter the evolutionary bias and indoctrination in astronomical and geological evolution.Read OnlineBuy Book