How do we know the Earth is Old? Biologos vs. Creation Ministries International

Biologos released a poster which really steamed two writers for Creation Ministries International. The poster details why academic scientists in physical and biological fields agree that the Earth must be older than 7,000 years (if you doubt that they do believe that, feel free to visit this link and read a very strong endorsement of an Old Earth from a very very illustrious collection of the world’s top academic scientists). Now I do not agree with everything that Biologos says, but I certainly like them much much more than I like Creation Ministries.

Creation Ministries published a paper delivering refutations of Biologos’ claims. Let’s look at the Biologos claims (BL), look at the CMI response (CMI), and see what we think.

Opening Statement

BL: There are several reliable ways to accurately estimate the age of materials on earth. Some methods measure radioactive atoms that decay at steady and predictable rates; others count layers that grow or are deposited in recognizable yearly patterns.

CMI: … There is only one way to reliably know the age of anything and that is by eyewitness testimony, on the basis of their written records…so how are the ages established? They are assumed, … all such ages rely on unprovable assumptions about the past. … a person can obtain any age that they like depending on the assumptions that they make. The methods described in this poster are … ‘observe and extrapolate’ methods of dating. These methods rely on three basic assumptions—(1) we can somehow know the initial conditions of the system from present observations, (2) the rate of change in the system currently observed is constant and measurable, and (3) the system is sufficiently resistant to interference that we are warranted in extrapolating the rate of change back thousands, millions, or even billions of years based on a few decades’ worth of data.

Science and Religion: If the only way to know the age of anything reliably is to have eyewitness testimony, consider this: do you have a clock in your house? Of course you do. And do you watch it all day? Of course not, you have a job or go to school, you have hobbies and other pass times. So when you get home at the end of the day, how do you know your clock is still accurate if nobody was there to eyewitness it?

You do make an assumption there. Your clock works on mechanical or electrical processes that operate with a predictable rhythm and pattern; you assume that even when you aren’t looking your clock continues to operate in the same way because the physical processes controlling it are constant.

We use that assumption, plus a fact about the world – that when my clock is working under the guidance of physical laws it keeps accurate time – to infer that my clock which was accurate this morning is still accurate this evening. Inference means something is very likely to be true. So long as the laws of physics governing it operate uniformly, the clock will keep time.

So all we assume here is that the laws of physics don’t make an exception for time or place – they are constant and predictable. That assumption is a perfectly valid and safe one to make. Life would be chaotically unpredictable if it wasn’t. In fact, every observation that has ever been made by anyone is consistent with the statement that physical laws and causality operate consistently with no exception for time or place. Nobody can produce an observation to the contrary.

In fact, if it were the case that we could not trust physical laws to be constant absolutely no science could be done! If causality could not be relied upon the world would be absolute chaos, you couldn’t even be sure you wouldn’t fall right through the floor at any moment.

As for the validity of each of the ‘assumptions’ in dating methods, we shall examine CMIs claims one by one.

So CMI can’t knock-em-down and drag-em-out with this argument. Assumptions like “the laws of physics make no exception for time or place” will not end up being fatal because, best we can tell (and we have spent a long time checking), that’s completely accurate and any special exceptions to physical laws behave in predictable, measurable ways.

Radiometric Dating

BL: Radioactive dating is based on the measurement of unstable types of atoms (isotopes) that decay at a predictable rate. There are many different radioactive atoms, each with its own rate of decay. Old rocks require dating using isotopes that decay slowly, because faster decaying isotopes have already gone.

CMI: .. all ‘ages’ calculated from these dating methods are based on assumptions about the past. In the case of radiometric dating the assumptions are: (1) we know the rock’s initial conditions, (2) the rock has remained a closed system for millions/billions of years, and (3) the radioactive decay rate of the isotope in question has remained constant all that time. All three assumptions are known to be unreliable…part of the standard dating procedure is to check the calculated ‘age’ against what is expected, and to change the assumptions so the result makes sense.

S&R: That’s actually false CMI.Those three things are not assumptions, all of them have been tested or can be tested experimentally.

Radioactive dating in a nutshell: Isotopes have a “half-life”, a physical property that predicts their decay rates. Randomly, all isotopes will shoot out alpha, beta, or gamma radiation. When they do, they turn into simpler isotopes or elements. Those simpler elements themselves have a half-life. Half-life is the time it takes half of a sample to undergo radioactive decay (but the sample is not gone in 2 half-lives, it is half the size after 1 half-life, a quarter the size after 2 half-lives, an eight the size after 3 and so on.) The initial element is called the parent isotope, and the element it decays into is called the daughter. So the ratio of parent to daughter tells us how many half-lives have passed.

‘Assumption’ 3, that decay rates are constant, has consistently been shown to be true. As long as the isotope is in the same inertial frame of reference as the observer (and all isotopes on Earth are in the same frame of reference) they undergo decay at the same rate. In fact, experiments have specifically tried to change the decay rates of isotopes under extremely high energy conditions in particle accelerators, but were unsuccessful. It may be possible in theory to change decay rates by increasing absorption rates, but the energy and pressure needed would have only existed in the big bang at a time when the universe was too high energy for atoms to exist.

Assumption 1, that we know the initial conditions, isn’t always true. But we don’t use or rely on radioactive dating techniques when it isn’t true. And the age of the Earth is based on a known quantity.

The oldest estimates of the age of the Earth using radiometric testing use Zircon crystals. Zircon is not a “rock” which is a mixture of many different elements and isotopes. Zircon is a “mineral”, a solid mass of a single ion (ZrSiO4). Zircon always forms the same way when it precipitates out of molten igneous rock.

Zircon crystals trap uranium suspended in Igneous magma when they form. Because of the charge and structure of Zircon crystals, they very conveniently do not allow lead inside of them when they form. Zircon forms all the time in volcanic magma today and we can, and have, examined fresh zircon in great detail. It invariably rejects lead.

Lead is what uranium ultimately degrades in to through a very long decay chain. So we know that zircon traps uranium and doesn’t trap lead. We know that uranium will eventually decay into lead. So if we find lead inside of a zircon crystal, we can chalk it up to radioactive decay; there is no other way for lead to get inside the crystal.

‘Assumption’ 2 – our samples are not contaminated with lead from somewhere else. Geo Physicists take great care to prevent this – they are careful not to select samples that are exposed to the elements for example, but instead they dig deep into the Earth where contamination is less likely. But there are better ways to tell if a sample is contaminated than that.

Zircon incorporates uranium in predictable quantities around 10 parts per million. It doesn’t matter that zircon doesn’t incorporate the same amount of uranium every time because it is the ratio of uranium to lead we are interested in. If a sample were contaminated it would be quickly apparent for two reasons.

First, there would be too much lead. There is very little uranium in zircon by percentage, so a daunting amount of lead must have come from somewhere else.

Secondly, it would be the wrong isotope of lead. This is important. Lead has several stable isotopes; Pb 204, 206, 207 and 208. If you find a piece of lead in the world it will be a predictable mixture of these four isotopes, with each isotope appearing in a predictable ratio based on its stability. But only three isotopes, Pb 206, 207, and 208 are part of the decay chain from Uranium into lead. In other words, the presence of Pb 204 instantly tells you that there is contamination.

But even that is not fatal! This is important, and CMI does not understand it, so read carefully. Because naturally occurring lead is a predictable mixture of those 4 isotopes, if you know how much lead 204 is in the sample, you also know how much of the other isotopes contaminated the sample! So we can still rely on radiometric dating because the contamination can be controlled for using more complicated mathematical models.

And that is exactly what it means when CMI says that part of the process is to predict the initial age and change the assumptions based on what is found. This is a process of selecting a model which either accounts for contamination or does not. We assume an uncontaminated sample, because we chose it carefully. If we find lead 204, we know that there was contamination so we have to change that assumption.

More complicated models have a greater degree of uncertainty, but that uncertainty is still only millions of years – in other words, the data can’t tell us if the Earth is 4.41 billion years old or 4.39 billion years old because of sampling error. That is a lot of years, but it tells us for certain that the Earth is at least 4.39 billion years and no older than 4.41 billion years.

So, like the clock in my house, using this dating method is based on only one assumption – that the laws of physics are constant. If they were not, no science could be done. The other three ‘assumptions’ are directly testable, and have been tested and accounted for in dating the Earth.

Listen, that section was complicated, especially if you don’t have a background in science. Please go back and read it once more if you are at all unsure what it said. It will be very important.

Missing Isotopes

BL: Experiments that collide atoms at high speed have allowed scientists to determine what isotopes would have been formed in stars and supernova events. Looking for these isotopes in nature, we find only the very long-lived varieties. The short lived isotopes are “missing” because the Earth is old enough for them to have decayed away. The longest-lived missing isotopes require at least 1 billion years to decay below detectable levels.

CMI: If [the scientists] did not observe it we know they are telling a story. It is just their subjective opinion … the claim here simply begs the question…why should we accept that all the isotopes in the universe formed billions of years ago in supernova events? There is in fact a decided lack of supernova remnants that should exist if the universe were billions of years old…If we accept that God created the earth in six days some 6,000 years ago as the Bible describes, why would God have created short-lived, highly radioactive, and harmful radionuclides? And even if he did create them, it’s likely that accelerated nuclear decay during Creation Week would have neutralized such radionuclides…

S&R Again, scientists have specifically tried to increase the rate of radioactive decay. It cannot be done under the laws of physics as we know them, so accelerated nuclear decay is not possible. If CMI is invoking miracles then their arguments cannot refute actual science. Miracles are fully outside the realm of science.

“It is just their subjective opinion” – that’s not correct. It is their inference based on evidence and known laws of physics and chemistry. Opinions are our subjective beliefs. Inferences are stronger than that, they are based on evidence and they are rationally considered. This is not like reading Hamlet, where in your opinion he was insane and in mine he was faking insanity. There is a right answer and there are ways to find it out with varying degrees of trustworthiness. the scientific method is one very trustworthy technique.

The postulate is also not question begging; it starts with a theory that is supported by evidence, and it finds further corroborating evidence! Being right is not question begging!

Based on astrophysical observations scientists say that “all the matter around came from high energy collisions in stars and super novae.” To test this, they simulate those high energy events in particle collides and see what comes out. They then see what kind of elements they find in nature. Those elements look exactly the same, except some are missing!

You would of course expect some isotopes to have decayed away by now, even the creationists thinks so. Theory corroborated! So we can see what’s missing and use that information to guess at when the raw materials for the Earth were first formed based on established knowledge and only one assumption: that physical laws have been constant.

And guess what? When we date the universe this way it gives us the same age we get from dating the Earth with radiometric U-Pb dating of Zircon crystals! That isn’t question begging, it’s evidence that the theory is correct! And not only that, two different processes conceived and tested independently by different people based only on one assumption (that the laws of physics are constant) gave us the same age!

The Creationist answer is not science. God made the universe without all those elements – why? And how would you tell if it was God or radioactive decay? Well we can SEE radioactive decay happening all the time. Can you see God? No, God is not something science can engage with. The creationist answer must be taken on faith. All we take on faith is that the laws of physics make no exception for time or place, something we must believe if we are to understand the most basic causal relationships, and something which is glaringly well established.

Radiometric Dating of Rocks and Meteorites

BL: The oldest rocks on earth come from the interior of continents, where erosion has exposed the deep crystalline basement rock. These rocks are over 3 billion years old, with the oldest being almost 4.5 billion. Multiple meteorites have also been dated, with the oldest consistently falling close to 4.5 billion years of age.

CMI: Consistently falling close to 4.5 billion years (Ga) of age? …There are many examples for most of the radiometric methods where dates in both terrestrial rocks and meteorites are significantly older than 4.5 Ga, even though they appear to be verified by the numerous ‘reliability criteria’ that geochronologists employ … these dates are interpreted in such a way as to conform to the accepted secular history of the earth … One typical rationalization is to invoke open-system behaviour in the rocks. Such anomalies are never considered a problem but presumed to explain more about the history of the rock, all of which is speculation and none of which has been observed! (Note for interest that the erosion of the interior of the continents was caused by the receding waters of Noah’s Flood.)

S&R: This has already been covered. Unquestionably different radiometric dating techniques have different applications and uses, and just as a screwdriver makes a poor hammer if you use an inappropriate technique you will find incorrect results.

As discussed above, these rocks date older because of exposure to naturally occurring lead. You can tell that lead occurred naturally because there will be Pb 204, which is not part of the U-Pb decay chain. This tells you you are dealing with an open system.

Knowing that naturally occurring (non-radiometric) lead always has a predictable ratio of the four stable isotopes, you can use the quantity of Pb 204 to tell how much of the other Lead isotopes contaminated the sample. It was never observed, but we know it to be the case that Pb 204 is never found inside of Zircon, so it must have gotten there from outside.

So at first we would have gotten a very old date and also found lead 204. Because it is established fact that Zircon rejects lead, including lead 204, and because it is established fact that nothing in a Zircon crystal decays into lead 204, we must adjust our model. This is not tinkering with the numbers after the fact to make the data fit, it is procedural science based on established facts and known physical laws.

As for erosion of the interior of the Earth during the flood, there are layers upon layers of rock which water cannot permeate. Artisan springs in the mountains occur where water is trapped between two such layers in a semi permeable stone and those layers are bent by geological processes. Most of the crust of the Earth is water tight, especially the igneous rocks we find Zircon in. And meteorites were not on Earth during the flood were they? So aging or contamination due to a worldwide flood is insufficient to discredit U-Pb dating of Zircon or meteorites.

Counting Methods

BL: Counting methods are based on observation of natural processes that produce a distinct layer with the passing of each year. For many tree species, slow growth in winter and rapid growth in summer produce a distinct annual tree ring. Some lakes produce annual sediment deposits called varves. Glaciers also preserve a record of annual sediment depositions between winter and summer.

CMI: .. what is being counted [is]not years. … It is now clear that multiple rings and layers are regularly produced in a single year, depending on such factors as climate and hydraulic conditions… some of these methods are calibrated against radiometric dating methods, which is tacit admission that the methods are not reliable..and … the calibrations introduce a calibration bias that stretches the timescale to fit the long age paradigm. All these techniques … ignore the effects of Noah’s Flood. …this annuls the assumptions behind these methods and is a factor that the long-agers are not even prepared to consider.

S&R: Actually, these calibrations are done because C14 dating has a unique problem – we know the decay rate, but the starting amount has changed over time. More on that later.  As for the specifics of each method, we shall see, but they will all boil down to exactly one assumption: that the seasons changed from summer to winter in the past, which is a specific instance of the assumption that physical laws operate with no regard for place or time.

The orbit of the Earth and the Seasons in a nutshell: The Earth orbits the Sun; it follows an elliptical orbit obeying laws of gravitation that were laid out by Newton and Kepler. As it orbits the sun the Earth also spins about its axis.

However, the axis of rotation is tilted. As the Earth orbits the sun, that tilted axis results in a summer and a winter in the Northern and the Southern hemisphere depending on which side is angled towards the sun. This rotation can be explained and measured using Newton’s laws of motion and the conservation of angular momentum.

The exact angle of the Earth’s tilt varies over time. This can cause more intense summers and winters. Over the past 100,000 years the angle of Earth’s tilt has changed about 7 degrees (it now sits as 23 degrees, but it was closer to 30). This means that summers are cooler now, but not by a phenomenal amount.

The important thing is that these changes in the cycles of the Earth are controlled by physical laws. Further, the cycles have been very stable over Earth’s history and virtually static over the past 100,000 years.

Tree Rings

BL: The oldest living trees have more than 4,000 rings. Because annual growth varies with yearly climate differences, the ring pattern of a tree core of known age can be matched with a tree core of unknown age (perhaps taken from a beam in an ancient cliff dwelling) to extend the ring count back in time. This process, known as cross correlation, allows reliable counting back to about 12,000 rings.

CMI: There is widespread evidence that many trees…produce multiple growth rings per year depending on environmental conditions. … further, the past climate patterns after the Flood were significantly different from what we have today, causing major uncertainty in tree ring dating. .. the extremes between different seasons were muted and the environment was in general much wetter, which would have produced faster growth rates. Therefore, growth rings would not have been correlated with seasonal extremes, but more likely with individual storm surges. Moreover, researchers construct long ‘chronologies’ from … fallen logs on the ground … and this is usually constrained by carbon dating the tree cores. This is … circular reasoning. Further, matching the tree ring pattern between separate samples is a highly subjective and flexible process. Without independent confirmation of the dates (which is best done by eyewitness testimony), this method is nothing but circular reasoning.

S&R: The evidence of multiple rings you are referring to comes from research done by the same community of researchers who date the trees! They understand how to look at tree rings because they wrote the academic literature on the point! Saying that the people who invented reading tree rings can’t read tree rings because of something in their own literature is actually silly.

Generally, trees grow in the summer and stagnate in the winter. This creates areas of dense wood when the tree grows slowly and areas of less dense wood when the tree is growing quickly. Of course quickly for a tree is still not that quickly. But this process produces bands on the inside of the trees. If the seasons are constant, these bands will alternate between light and dark each year.

A drought will produce years with relatively thin bands, and a rainy year will produce thick ones. We can see this using eyewitness evidence. Trees that were alive during the droughts of the 1930s have skinny bands in those years.

Trees were not always correlated using radiometric dating (which is not circular reasoning anyway. Radiometric dating confirmed what was already known about tree ring dating, proving it is also a reliable way to date trees). It is thought that rainy years affect all trees in roughly the same way and droughts affect all trees in roughly the same way. Imagine two trees alive in the 1930s. One died in 1945, the other in 1985. The tree that lived to the 1980s will have the skinny drought rings of the 1930s in the middle, while the one that lived to the 40s will have the skinny drought rings on the outside. And we can use this to date trees in an area, using overlapping patterns and counting backwards, moving from from tree to tree as needed.

To call this highly subjective is incorrect. It is difficult and requires an expert eye; one must know very astutely what to look for. And you need a microscope, which not everyone at CMI owns. But assuming that 1. The seasons are constant (which is based on what we know about astrophysics,) and 2. Trees in the same area are affected the same way by the same weather (why wouldn’t they be?) there is nothing wrong with relying on this science which is exactly why it was later independently corroborated by radiometric dating.

So as long as we believe that in the past winter changed to summer every year (which everything about astrophysics tells us is true) then using tree rings is perfectly sensible, as they just are a visual representation of these annual changes.

As for Noah’s flood, there is absolutely no compelling geological evidence that such an event took place. Why are fossils layered from simple to complex? Why are there angular unconformities in sedimentary rock? Why is erosion not uniform world wide? Why did the ancient oceans have different salinity when they should have mixed into a solution? Why didn’t all the trees drown simultaneously?


BL: Layers with actively forming varves can be found with 100,000 or more layers. Each lake sits on complex rock layers that have their own history. Based on these modern lakes, the age of the Earth must be older than 100,000 years. In ancient lake deposits now turned to rock (such as the well-known Green River Formation), millions of layers are preserved, suggesting the Earth’s age exceeds several million years.

CMI: Varves are a favourite of long-agers, and have been since they were selectively defined as annual layers, this is merely another case of question-begging in favour of millions of years. First, there is experimental and observational evidence that demonstrates that layers form automatically when sediment composed of different sized particles is deposited from moving water. Moreover, multiple layers are deposited at the same time and they give the appearance of varves but are not annual layers. Second, for these varves to produce the sort of ‘clock’ that is here supposed we have to assume that the environmental conditions remained stable enough to produce this pattern over 100,000 years in the case of modern lakes, and for millions of years in the case of the Green River Formation. The evidence from so-called varves is consistent with the biblical timescale of thousands of years

S&R: Varves form along rivers and lakes. In the winter months, water levels drop and in the summer water levels climb. During rainy times, water runs down into lakes and rivers carrying sediment with it. During the dry times, the sediment has a chance to rest and get compacted. This produces bands in the rock based on annual seasonal changes; like tree rings we can see when there was growth and change happening and when there was stagnation based on alternating layers of sediment. These layers alternated based on rain and water-level, which is itself based on the seasons. That is why varves were defined as annual bands. The observation, not the definition, came first.

Layers do form when moving water deposits sediment,but a verve does not form every time it rains. Varve layers are very large and thick, far too thick for a single rainfall to carry enough sediment to create a layer. A varve is the sum of a season of rain, not a single storm.

You do get a thick layer of sediment in a flood, but those layers do not look like varves. They look ordered, from heaviest sediment at the bottom to the lightest at the top. Varves are uniform. If all the Earth was covered in water which suddenly dried up we would not find varves as a result.

CMI is right in that we have to assume that the changing seasons each year also changed for the last million years. That is a perfectly reasonable thing to think based on everything we know about astrophysics (which is alot). Noah’s flood would not have produced the regular, rhythmic pattern of varves we find today. It would have dropped tonnes of sediment all at once in order of heaviest to lightest everywhere in the world. That isn’t something we find.

Again, we are making exactly one ‘assumption’, that the seasons are a constant (which is an instance of ‘the laws of physics are a constant).

Ice Cores

BL: Ice cores from Greenland and Antarctica preserve the longest record of snow deposition. In Greenland, the annual layering can be visibly counted down to about 50,000 layers. In Antarctica, the annual snowfall is less than Greenland, causing less thinning of the layers due to compactions, resulting in more than 400,000 measured layers.

CMI: One problem is with the identification of the layers. Another is that multiple layers formed each year depending on environmental changes, especially in the earlier, deeper parts of the core. It’s the deeper parts of the core where the layers are increasingly difficult to identify, and this significantly affects the reliability of the ice core ‘data’. The interpretation of the cores, driven by the long-age philosophy, has many problems. They are better interpreted as forming after Noah’s Flood during the Ice Age and beyond.

S&R: Antarctica and Greenland both have summer and winter. In summer, the top layer of ice and snow melts a bit during the day. In the winter, snow accumulates. Next summer, this new snow melts a bit. This pattern alternates over years as the glaciers build. When the snow accumulates a light colored band appears and when the snow melts into ice a dark colored band of thick ice appears. When you look at a 50,000 year ice core with the naked eye it is hard to see the individual bands (It doesn’t snow much in these places, so each band is small) but if you examine one with a microscope the bands are visible plain as day. Here’s an example – the light bands are accumulation periods and the dark ones are melting periods. Can you identify the layers? Is it as hard as CMI made you think?

Ice core sample showing bands of annual accumulation

Even if dating the bottom of the ice core is difficult, That’s the oldest part. We count DOWN from the top layer, this year’s layer, backwards to age the core. Even if the very oldest layers run together, the vast vast majority of the core is not. We can tell clear as day the 10,000th layer from the 10,001st layer.

Also, the core gives us more data than the number and size of layers. It also has air bubbles trapped in it. We can look at those air bubbles and measure atmospheric carbon dioxide. That allows us to corroborate our results between other cores and, you guessed it, all the cores gel perfectly.

Not only that, but years where there was a lot of snow melting also tend to be years where the tree rings grew quickly! That is, we can find consistent patterns about the global climate which corroborates tree ring data. When two separate, independent methods produce the same results it is very indicative that those results are correct.


BL: Cave growths forming in regions where local climate varies seasonally between wet and dry or cold and warm will form an annual layer similar to tree rings. In some cases, cave formations preserve more than 200,000 annual laminations.

CMI: The description “annual” here is unobserved, subjective speculation … Long-term climate changes affect the rates at which the speleothems form within caves, and the climate changed considerably after the Flood….Moreover, the speleothems formed after the cave itself was carved …The initial carving of the caves is explained by upwelling of hydrothermal solutions, which would have occurred during and after the Flood.

S&R: Again, while we cannot observe the steleothems accumulating in the past, we know how they accumulate today. During the wet, rainy period of the year sediment continually drips down through the cave and is deposited in the form of moist steleothems. In the dry season those structures harden. We can see it happening, we can watch new rings being added all the time at the rate of one per year, with each ring corresponding to the cycle of winter and summer.

Now there is absolutely no reason to think that those structures formed in a different way in the near past. Each year there is exactly one winter season and one summer season as the result of the tilting of the Earth as part of its orbit and Earth’s orbit has been stagnant for a long time. There’s nothing even remotely compelling to make us think that these processes used to be different over the period that the steleothems formed.

Further, steleothems accumulate more in wetter years because more water comes bringing more sediment with it. And, if you didn’t guess, years where steleothems grew quickly also turn out to be years where trees grew quickly. The two methods of dating correlate nicely in research done by independent researchers.

So again, the only thing that we are assuming is that the seasons continue to operate the way they do now. The seasons change as a result of the orbit of the Earth, which is itself operated on by gravitation. So unless the Earth had a drastically different orbit recently there is no reason to think that steleothems are unreliable.

Ocean Spreading and Dating

BL: Satellites measuring distances between continents show that they’re moving. Africa is currently moving away from North America at a rate of about 1 inch per year. New Ocean floor is created at the Mid-Atlantic Ridge as the continents move apart. This creates a testing opportunity for the reliability of radioactive dating. If the radioactive dating works reliably, the calculated rates using the radioactively determined ages should be approximately 1 inch per year—and they are!

CMI: This is an impressive claim but again we need to ask ourselves what has actually been observed. There is no reference to where this test has actually been reported in the literature, so it is an unsubstantiated assertion. This claim suggests that the rate of plate movement has remained constant for millions of years. However, the satellite data only goes back a few decades. Is it valid to extrapolate today’s rate over thousands of kilometres? This is an open question in the creationist literature …The Catastrophic Plate Tectonics model assumes the general pattern of relative age preserved in the radiometric signature of the ocean basins but shows how this can be interpreted within the biblical timeframe.

S&R: Now we haven’t been asking for references to the academic literature to this point, we’ve been taking the science as given for the sake of argument. This makes the creationist look cornered. But in fact there are lots of experiments on the ocean floor one can find that demonstrate this and other geological principles. It is demonstrated by radiometric dating that on average an inch of ocean floor corresponds to one year. This isn’t done inch by inch of course, that would be too difficult and time consuming, and traveling kilometers between samples still shows the effect just as clearly.

Actually, plate tectonics can also be traced further back than what satellite data allows using ocean floor studies. When new ocean floor forms at the spreading center, it is new liquid rock turning into basalt. It forms like any igneous rock, containing normal minerals like zircon, silicon, lead, cobalt, iron, and nickel.

As you know, iron, nickel, and cobalt are magnetic. And it just so happens that when there ferromagnetic materials precipitate out of magma they are free to move around the fluid rock until the other precipitates trap them (but iron precipitates out early, so it is free for some time before this happens). So where do magnets want to point? you got it, North! They behave exactly the way a compass does.

Now what do you suppose it looks like if we look at the magnetic minerals in the ocean floor? If they all formed at one time, all the magnets should be facing due North. But as it turns out, they are not! Each inch you move makes the magnets further and further out of line with Earth’s North Pole; if you move towards the center of the spreading zone the magnets get more and more aligned with the north pole until, at the center, they are perfectly aligned.

Further, every million years or so the Earth’s magnetic poles switch! Craziness! You can tell when it happened because if you look at the ocean floor’s magnetic elements they are in bands that flip every million inches! Craziness, right? And because this pattern of geomagnetic inversion is predictable, it acts like a time traveling ocean floor speedometer.

You also find the exact same thing when you look at volcanoes; magma builds up in layers of rock, and some layers are magnetically inverted.So known major eruptions also help corroborate this dating method’s reliability.

And, if you want to guess, radiometric dating places inverted rock on the Ocean floor in the same time periods as inverted rock on Earth’s surface! Once again, the time measurements between radioactive dating, ocean spreading, and geomagnetic inversions all line up neatly. And how could the flood have changed the magnetic poles of the Earth or made the Ocean spread faster?

Correlating Radiometric and Other methods of Dating

BL: Counting tree rings and varves assumes that each layer represents 1 year. Radioactive dating assumes decay rates have been constant over time. We can put all these to the test at the same time by combining the data. When we compare the carbon-14 content of cross-correlated tree rings and varve samples from Lake Suigetsu in Japan, they confirm the validity of radioactive dating methods.

CMI: Actually the results from the different methods do not agree. The researchers produced a calibration curve for carbon-14 in order to adjust for the discrepancies between the methods. But what they are unable to correct for are factors that affect all methods, and there is one such factor which they have ignored—Noah’s Flood. This event upset the carbon balance on earth which means increasingly larger corrections are needed for carbon-14 results as we approach the date of the Flood

S&R: Varves and tree ring data lined up with each other but did not gel perfectly with C14, so calibration was needed.

Carbon, like lead and uranium, has several stable isotopes. Carbon 12 and Carbon 13 are very stable, but Carbon 14 is not.Carbon 14 has a well known half-life of roughly 5,700 years.

C14 is produced when cosmic rays hit the atmosphere; it forms part of the air around us and permeates into the oceans. Living things breath in the air and drink the water, which is part carbon. And that carbon is a mixture of Carbon 12, C13 and C14. So Carbon 14 gets into living things based on how much C14 is produced in the atmosphere.

Once a living thing dies, it stops taking in carbon. This means that no more carbon 14 is taken in. The C14 in the organism then starts to undergo radioactive decay, and it has a short half life (making it only useful in dating living things that are no more than 45,000 years old or so). We know how much C14 is lost each year, so we can tell how far apart two living things died using C14 – this is the distance in “uncalibrated years”. All we do is measure how much C14 is left in a thing, knowing that when it died the carbon in its body would have been a mixture of all the carbon isotopes based on their relative abundance.

The problem is that atmospheric C14 has not been constant; it is produced by cosmic rays, which fluctuate in intensity based on how active the sun is. The sun goes through very very long cycles of rising and descending activity. So we can know how much more carbon 14 one thing has left than another.

So we can’t directly measure how much C14 was in the atmosphere at any point in the past. We could see how much was left over, but without knowing the initial quantities that didn’t mean much. We could tell that tree A was 100 years older than tree B, but we could not tell their absolute age in “calibrated years”.

So we used other dating methods in combination with C14 dating. If we date the different layers of a tree or a varve or a speleothem, knowing that each layer is a single year, we can measure the C14. Knowing the decay rate of C14 is easy, so we can figure out how much C14 would have decayed in that period. From those two pieces of information we can measure how much C14 there was initially! Later we could use ice cores to see if our math worked; air bubbles trapped in the ice cores had ancient C14 stuck in them, and the air bubbles had the right amount of C14 based on data from speleothems.

So yes, C14 dating had to be “calibrated”. This was done to bring it into alignment with dating instruments that we knew to be accurate. This is not because the dating method was unreliable but because the initial quantity of C14 was unknown. But because the decay rate is constant and because we know contamination is impossible in this instance (C14 is found in the air and it moves into water and living things. Dead things don’t absorb C14) it follows that we can figure out the initial levels of carbon 14 by using other dating methods. The changes in atmospheric C14 over time is what we wanted to know all along – that was the point of calibration.

So Calibration of C14 was not done to make several methods of dating line up fraudulently or arbitrarily. It was done to establish an absolute timeline against which C14 can be measured. C14 dating can now work in either calibrated or uncalibrated years depending on the needs of the researcher; that is, we now can say that X is so many uncalibrated years older than Y, OR we can say that X is so many years old absolutely!

As for Noah’s flood affecting the C14 distribution, this makes no sense. C14 forms when cosmic rays interact with the atmosphere 10 to 15 kilometers above the Earth, which is the tropopause. Weather conditions in troposphere do not affect either the stratosphere or the tropopause, so even a lot of rain clouds would not affect C14 production. Unless the building of the flood caused more cosmic rays to hit the Earth there would not be more C14.

Confirming Radiometric Dating with Known Historical Events

BL: Radioactive dating methods applied to deposits of known age, such as ash from the 79 AD eruption of Mount Vesuvius in Italy, have yielded correct ages.

CMI: A test based on eyewitness reports is the only valid test for radiometric dating. All the above ‘cross-checking’ methods compare methods that all use the same basic assumptions, so they are not independent tests of reliability. They could all be influenced by an unidentified factor, or cases of confirmation bias. Concerning this confirmation with Mount Vesuvius …  The article proves the dating methods are not independent. In this case, they collected a sample of sanidine from pumice of known age based on historical eyewitness reports of the 24 August 79 AD eruption … Their total argon gas results gave an age of 3,300 years, which they knew was wrong because the correct answer was 1,918 years. So, using the known age they calculated the amount of ‘excess’ argon. The paper is a warning to researchers to watch out for excess argon.

S&R: Again, this misinterpretation of radiometric dating is based on a misunderstand of how radiometric dating works. When igneous magma is expelled from the Earth it contains Potassium 40 which degrades into Argon 40, but the magma also contains naturally occurring Argon 40.

Argon 40 passes through the liquid rock whereas potassium 40 doesn’t – so K 40 ends up getting trapped in air bubbles while Ar 40 vents out of the magma. So if you find an air bubble in magma you know that when it formed it contained only K 40, and any AR 40 is from radioactive decay.

Unfortunately, contamination is a problem once again. Ar 36 and Ar 40 occur naturally in the air and often contaminate samples. Fortunately, we can use math to solve this problem the same way we did with Zircon.

Naturally occurring argon has a well known decay chain. Further, argon in the air always occurs in the same ratio of Ar40 to Ar36. We can measure how much K-40 there is in a sample and how much of each of the different argon isotopes are found in the same sample, that’s easy enough. Then, using some complicated math, we can find out how much K-40 there was originally and how much AR-40 there was originally was. The math is the same as is used finding out how much naturally occurring lead is in Zircon,

So yes, extra Argon is a problem – but determining how much extra argon there is is not a question of wild speculation but complicated and reliable mathematics. The problem with “extra Argon” is easily solved because the extra Argon is the wrong kind of Argon.

Closing Points

BL: Through various scientific methods, we can test, retest, and cross-examine to find the right answer.

CMI: And here is the fundamental assumption on display for how we can supposedly know that the earth is old—science will tell us the story. … But does it? Consider Jesus’ miracle at Cana of turning water into wine. We could conduct chemical tests on the wine,… But because numerous people saw that the wine was water mere seconds before, any inference we make about a vineyard origin of the wine from the chemical analysis will be wrong. …This is why we need to begin with God’s eyewitness testimony when we investigate natural history…BioLogos has presented a very brief and misleading version of what actually goes on in these methods, presented the interpretations of these methods for chronology as ‘reliable evidence’, and proclaimed old-age chronology correct by fiat. Most of their ‘cross-checking’ methods beg the question in favour of long-age assumptions. The one independent test for long-age dating methods, historical witness, proves to be the one standard these methods fail against…What we don’t accept are the assumptions long-agers make about the past. We don’t accept that prehistory is a given. We don’t accept that natural processes (and in some cases, their rates) have basically remained the same throughout history. We don’t accept that we can implicitly trust forensic science to ‘tell’ us about this prehistory. And we don’t believe that nature is all that matters for natural history.

S&R: Big finish! CMI says that science is wrong about all miracles and that may just be true. Luckily zircon crystals do not form by miracle. Zircons do not exclude all lead and incorporate uranium by miracle. Uranium does not turn into some lead isotopes and not others by miracle.The clock on my wall does not run on miracles. We are not talking about miracles, we are talking about natural causes and physical laws in the world we live in. If we cannot depend on the laws of causality and physics to be constant we cannot do science. If we cannot depend on causality we cannot even make a single prediction about the future!

The cross checking, as we saw, was not question begging but mutually corroborating. These cross checks also gel with historic eyewitness testimony (contrary to misapprehensions by CMI about how radiometric dating works – Argon 40 is not the same as Argon 36.) The only assumptions we are making are about the constancy of physics; the constancy of natural processes is entailed by the constancy of physics and does not need to be assumed if physical laws are reliable.

Physical laws are known to be constants; they make no exceptions for time or place. Decay rates are constant – we have tried to change them using the most powerful particle collisions since the big bang but weren’t able to. The orbit of the Earth and the seasons have not undergone any significant changes for as long as the Earth as been solid on the outside, meaning the seasons have been roughly constant for that period.

We don’t accept that prehistory is a given – there are mountains of evidence as should be clear from the above discussion.

We don’t accept that natural processes (and in some cases, their rates) have basically remained the same throughout history – fundamental properties of matter make no exception for time or place. The laws of physics (natural processes being a simple instantiation of one such law, gravitation) make no exception for time or place. Causality makes no exception for time or place. These are not assumptions – they are the sum of every observation ever made! Nobody has ever made an observation which has contradicted these points!

We don’t accept that we can implicitly trust forensic science to ‘tell’ us about this prehistory – you’re not being asked to implicitly trust anything. You’re asked to make observations about the world and accept that physical laws are constant (which has all the evidence in the world behind it). The observations, in tandem with the prolonged operation of physical laws, are what you trust. That trust is not implicit, not should it be. It is based on evidence, rationality, and scientific argumentation.

And we don’t believe that nature is all that matters for natural history.

After all the allegations of question begging we just heard, that’s how you’re going to close this argument CMI? What is it matters to the history of the universe which is not the universe or any part of it? Because if it’s something outside the universe that fundamentally begs the question against science; science can only deal with the things that make up the universe, and you’re saying that whatever controls events in the universe is the sort of thing which can never be seen, tested, or observed by anyone ever no matter what (but never the less that thing is undoubtedly real and the only valid topic in science class?)

To put it bluntly, saying that nature is not all that matters to natural history is very literally self contradictory. I put an emphasis on that because it’s so very rare to argue against someone who makes such a ridiculously incorrect point.

If you don’t believe that physical laws apply to the universe constantly you don’t believe science is at all possible. If you think that whatever controls the universe is something outside of it you have no reason to believe in causality. No evidence can possibly stand for either of those propositions because that evidence would be the fundamental opposite of what we mean when we say the word evidence.


2 thoughts on “How do we know the Earth is Old? Biologos vs. Creation Ministries International

  1. Natural Historian

    Wow, a very thorough analysis. I had seen the infographic and the CMI response and your responses are excellent. CMI’s responses are all canned responses to these evidences of an old with nothing original really. I see that one of the authors if Tas Walker a prolific writer for CMI but what caught my eye was the other author is someone with a bachelors in “natural resource management” and is an editor for their technical journal and has written articles himself. That editors of their technical journal have such little experience just amazes but doesn’t really surprise me when I read the articles. Joel

    1. 4n0nymous Post author

      Thank you, that’s gratifying to hear. I tried hard to keep my research tight and my responses concise, which made for quite a time consuming post. I agree that, while CMI boasts quite a lot about the qualifications of its staff and its writers, my experience has been that much is left to be desired in the quality of CMI’s publications. Problems with incomplete scientific knowledge or grossly out-dated science abound; those are not the worst of CMI’s problems by a long-shot, but with such an expert staff bad science is undoubtedly the least forgivable of their problems.


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