Contents by minimum age
Yes, it really is 4.5 billion years old.
The evidence against a recent creation is overwhelming. There is perhaps no greater attack upon science and rational thought than the doctrine of a recent creation of the planet Earth and/or the universe. This article collects known evidence that places a minimum age of the Earth beyond the usual 6,000 years quoted by Young Earth creationists (YECs). Deep time is the idea, held to be credible by natural researchers since the early 19th century, that the Earth is millions or billions of years old, rather than the few thousand of young earth creationism. The accepted age of the Earth is about 4.54 billion years, while the entire universe is around 13.77 billion years.
These ages weren't just made up. They were devised from a range of experiments and observations made across multiple disciplines of science such as astronomy, geology, biology, palaeontology, chemistry, geomorphology and physics. They have been revised several times based on new evidence, but never to the degree of the many orders of magnitude required to bring them in line with Biblical literalism. YECs, however, ignore these experiments and evidence in favor of pseudoscience and their biblically-based view that the world was created by magic.
The entries below are listed in alphabetical order, while in the contents box they can be found listed by the approximate minimum they put on the age of the earth. It is also important to note that these dating methods are not mutually exclusive: where their range, accuracy and applicability overlap, the dates they produce are concordant with each other. It should be noted that YECs regularly claim that all types of radiometric dating are unreliable, going so far as to attempt to discredit the discipline through dishonest practices.
 Amino acid racemization
Amino acid racemization dating is a technique that is used to date fossilized objects up to several million years in age. The naturally occurring amino acid molecules usually possess a carbon centre with four different groups joining it; a hydrogen atom, the amino group, the acid group (hence the name of the class of molecule) and a side chain, which is what distinguishes amino acids. In three dimensional space, such a molecular topology can occupy one of two configurations. Convention labels these as D or L, which are referred to as stereoisomers and are essentially mirror images of each other. The ratio of these two isomers is initially unequal. With only one exception, naturally occurring amino acids used in polypeptide synthesis are in the L form. Over time this will decay to a more balanced state in a process called racemization, where the ratio between L and D stereoisomers will be equal (a racemic mixture).
Measuring the degree of racemization and other known quantities can show an estimated age of the sample. This is measured fairly unambiguously by the fact that different stereoisomers rotate plane polarised light in opposite directions (it is this interaction that determines the D and L labels) and so a ratio can be determined by contrasting an unknown sample with a pure D or L sample and a racemic mixture. By measuring the racemization of the amino acid isoleucine, for example, objects can be dated up to several million years old.
While it is true that there can be great variability on the rate at which amino acids undergo racemization, the changes in humidity, temperature, and acidity required to make the oldest known samples conform to a young earth (under 6000 years) view are completely unreasonable. Such conditions would destroy all traces of the amino acids rather than just leave a racemic mixture of the molecules behind.
 Baptistina asteroid family
The Baptistina asteroid family is a cluster of asteroids with similar orbits. This group was produced by a collision of an asteroid 60 kilometers in diameter with an asteroid 170 kilometers in diameter. Researchers from the Southwest Research Institute (SwRI) and the University of Prague have traced the orbits of these asteroids back from their current locations and estimated that the original collision happened 160 (±20) million years ago. 2011 data from the Wide-field Infrared Survey Explorer has revised the collision date to 80 million years ago.
 Continental drift
Based on the continuity of fossil deposits and other geological formations between the South American and African tectonic plates, there is much evidence that at some point in history the two continents were part of the same landmass. Because tectonic drift is an incredibly slow process, the separation of the two landmasses would have taken millions of years. With modern technology, this can be accurately quantified. Satellite data has shown that the two continents are moving at a rate of roughly 2 cm per year (roughly the speed of fingernail growth), which means that for these diverging continents to have been together at some point in history, as all the evidence shows, the drift must have been going on for at least 200 million years.
Corals are marine organisms that slowly deposit and grow upon the residues of their calcareous remains. These corals and residues gradually become structures known as coral reefs. This process of growth and deposition is extremely slow, and some of the larger reefs have been "growing" for hundreds of thousands of years. The Great Barrier Reef Marine Park Authority estimates that corals have been growing on the Great Barrier Reef for 25 million years, and that coral reef structures have existed on the Great Barrier Reef for at least 600,000 years.
 Cosmogenic nuclide dating
The influx of cosmic rays onto the earth continually produces a stream of cosmogenic nuclides in the atmosphere that will fall to the ground. By measuring the build-up of these nuclides on terrestrial surfaces, the length of time for which the surface has been exposed can be inferred. This technique can be used to date objects over millions of years old.
Dendrochronology is a method of dating based on annual tree growth patterns called tree rings. Tree rings are the result of changes in the tree's growth speed over the year, because trees (in normal conditions) grow faster in the summer and slower in the winter. Thus, a tree's age can be found by counting the rings. Dendrochronology is the only method on this list that can date events precisely to a single year.
Even dates derived from individual trees are contradictory to the recent creation doctrine, since the oldest trees are old enough to make a global flood impossible. However, it is possible to extend the chronology back by using many different trees. The thickness of tree rings varies with the local seasonal weather, so a sequence of thick ring, thin ring, thin ring, thick ring, thick ring, thick ring, thin ring, thick ring shared by two trees is strong evidence that the corresponding rings formed at the same time. Each individual tree only covers the span of time it was alive and growing, but as these spans overlap it is possible to match up overlapping sections and work backwards. By observing and analyzing the rings of many different trees from the same area, including fossil trees, the tree ring chronology has been pushed back in some areas as far as 11,700 years.
 Distant starlight
The fact that distant starlight can be seen from Earth has always been a major problem for the young Earth idea. Because the speed of light is finite, what you are actually seeing when you look at an object is an image of that object from the past. "From the past" here has a few caveats regarding the relativity of our concept of the past, the future, and now. In the BBC Horizon program What Time Is It? physicist and former pop-synth player Brian Cox suggested that, as information cannot travel faster than light, and that time and space are relative, it can be considered that the stars actually are what they look like "now", in a manner of speaking. Either way, though, the bottom line is still the same; the light has travelled a certain distance, for a certain time, before arriving on Earth to be seen by our eyes or telescopes. We can use this data to put a minimum time on the existence of the universe, by looking at how long some light has been travelling for.
On Earth, the delay caused by the speed of light is incredibly minor — when you look at an object a mile away, the light has been travelling for five microseconds. When you look at the Sun, you are seeing light that has been in transit for 8.3 minutes. It's more noticeable with sound and distant objects, but only because the light from things such as distant explosions or jet fighters is so much faster. There's still a delay and transit time for the information that says whatever made the light/sound must have been around that long ago to produce it.
On the cosmic scale of things, this delay is far from minor and really is noticeable. When astronomers look at the closest star to Earth (Alpha Centauri), which is roughly four light years away, they are seeing the star as it was four years ago from our perspective. When astronomers look at objects in the region of space known as the "Hubble ultra deep field", they are seeing the stars there as they were over ten billion years ago. Light we are receiving from these fields has been travelling for ten billion years, and the universe must have, therefore, existed long enough for that transit time to take place.
Therein lies the problem for young Earth creationism; if the universe is only 6,000 years old, how can objects billions of light years away — and therefore billions of years old — be seen?
There are a few creationist "zingers" to solve this problem, but are almost exclusively centred around pretending the problem doesn't exist. One is omphalism, which suggests the light was already in place and on its way 6,000 years ago, which is basically like saying that "6,000 years ago, the world was created 14 billion years ago", which is a form of Last Thursdayism. They also like time dilation fields and changing the speed of light, but this requires a lot of Goddidit to make it work, as there is zero evidence for why the speed of light should change. There are a lot of issues surrounding changing fundamental physical constants such as c, namely that according to E=mc2, increasing c to make the world 6,000 years old would lead to normal radioactive decay blowing the planet up. Qualified astrophysicist Jason Lisle came up with the "anisotropic synchrony convention", which exploits how to reliably measure of the speed of light, but suffers from special pleading in that it assumes a highly unlikely physical reality deriving from a mathematical quirk is literally true - and there is no additional evidence for such a thing.
Many places on Earth show evidence of erosion taking place over very long time periods. The Grand Canyon, for instance, would have taken millions of years to form using the normal rate of erosion seen in water. Nevertheless, Young Earthers insist it was cut in a few years following the Great Flood - but in order for this to happen the rocks of the Kaibab Plateau would have needed to have the solubility of granulated sugar, rather than the more solid stone that it's made of. VenomFangX of YouTube claimed that the Grand Canyon would have formed in about "5 minutes", which at the very least would require the water to travel 5-6 times the speed of sound.
In the case of the Yakima River in Washington State between Ellensburg and Yakima, the river meanders with many oxbows typical of a slow-moving river on a plain, yet it is set within a deep canyon with visible layers of erosion. The only possible explanation is that the pre-existing river maintained its original bed as slow tectonic forces caused the surrounding land to rise underneath and around it.
 Fission track dating
Fission track dating is a radiometric dating technique that can be used to determine the age of crystalline materials that contain uranium. As uranium decays, it sends out atomic fragments, which leave scars or "fission tracks" in crystalline structures. Because decaying uranium emits fragments at a constant rate, the number of fission tracks correlates to the age of the object. This method is generally held to be accurate, as it shows a high degree of concordance with other methods such as potassium-argon dating.
 Geomagnetic reversals
A geomagnetic reversal is a change in the polarity of the Earth's magnetic field. The frequency at which these reversals occur varies greatly, but they usually happen once every 50,000 to 800,000 years, and generally take thousands of years. This fact is obviously inconsistent with the notion of a young Earth; around 171 reversals are geologically documented, which would make the Earth at least 8.5 million years old.
There is a mathematical relationship between a star's mass, the rate at which it spins and the star's age. Stars spin at a lower rate as they age. The mathematical model has been tested against over 30 stars whose age was previously known using other techniques and is shown to be accurate within 10% for stars in the 1 billion to 4.6 billion years old range. 
The composition of the Sun changes as it ages. The differing composition changes the way sound waves behave inside the Sun. Using helioseismic methods (models of pressure waves in the sun), the age of the Sun can be inferred. Using this method, an Italian team came up with an age of 4.57 +/- 0.11 billion years.
 Human Y-chromosomal ancestry
The Y-chromosome, unlike most DNA, is inherited only from the father, which means that all DNA on the human Y chromosome comes from a single person. This does not mean that there was only one man alive at that time, but that a single man's Y-chromosomal DNA has out-competed the other strains and is now - not taking into account smaller and less drastic mutations - the only one left. Because the only factor affecting the makeup of the DNA on the chromosome is mutation, measuring mutation rates and extrapolating them backwards can tell you when this man lived. The most recent calculations put this common ancestor as having lived 340,000 years ago.
There is a female equivalent: Mitochondrial Eve. Since the mitochondria in sperm are in the tail (which does not enter the egg), the DNA contained therein comes from the egg. Mitochondrial Eve, similar to Y-chromosomal Adam, is the most recent woman with an unbroken female line of descendants. She is estimated to have lived from 99,000 to 200,000 years ago.
Hilariously, some creationists have taken this to mean that science has found the biblical Adam and Eve and evolution has thus been disproven. But they probably weren't contemporaries and almost certainly never met. They aren't even fixed people; if branches of Adam's male line or Eve's female line die off, the title shifts to whoever currently meets the definition.
 Ice layering
Ice layering is a phenomenon that is almost universally observed in ice sheets and glaciers where the average temperature does not rise above freezing.
Annual differences in temperature and irradiation cause ice to form differently from year to year, and this generates alternating layers of light and dark ice, much like tree rings. This method is considered a relatively accurate way to measure the age of an ice sheet, as only one layer will form per year. While there have been a few cases where several layers have formed per year, these incidents do not challenge the ability of ice layering to provide a minimum age, as these false layers can be discerned from the real thing upon close inspection.
Currently, the greatest number of layers found in a single ice sheet is over 700,000, which clearly contradicts the idea of an Earth less than 10,000 years old. Even if one were to assume an absurdly high average of ten layers per year, the age demonstrated by this method would still be far greater than that suggested by young Earth creationists.
Nevertheless, the minimum age of the Earth identified by these means is 160,000 years. (+/- 15,000 years.)
 Impact craters
The number of impact craters can provide a probable lower limit on the age of the Earth. Asteroid strikes that can produce craters on the order of kilometers across are extremely infrequent occurrences; the chance of an asteroid with an Earth-crossing orbit actually striking the planet has been estimated at 2.5 x 10−9 yr−1, and when multiplied by the estimated number of Earth-crossing asteroids this approximates about one collision for every 313,000 years. If this frequency is correct, the number of impact craters on Earth were it only a few thousand years old should be very few. The most logical number of observable >1km impact craters for a young Earth would in fact be something like zero — a number that is completely at odds with the observable evidence, since over one hundred such craters have been discovered .
Even if creationists were to present some scenario in which many dozens of large asteroids could hit the Earth in less than 6000 years, there are still tremendous problems with this idea. The largest asteroid impacts are some of the most catastrophic events the world has ever seen. In Antarctica there is a crater 500 km in diameter which is calculated to have been caused by an asteroid 48 km in diameter roughly 250 million years ago. How the life we see today could have survived such an incident (if it had occurred in the last 6000 years) is a serious problem for YECs; an asteroid impact that big would have led to the extinction of all medium to large size species, an event that — given the creationist model; short time frame, no evolution — the world would have never recovered from.
 Iron-manganese nodule growth
Beryllium-10 (10Be) produced by cosmic rays shows that iron-manganese nodule growth is one of the slowest geological phenomena. It takes several million years to form one centimeter (and some are the size of potatoes). Cosmic ray produced 10Be is produced by the interactions of protons and neutrons with nitrogen and oxygen. It then reaches the earth via snow or rain. Since it is reactive, it gets absorbed by detritus material, within a timespan of about 300 years- very short compared to its half-life. Thusly, 10Be is excellent for use in dating marine sediment.
 Lack of DNA in fossils
Deoxyribonucleic acid (DNA), the universal carrier of genetic information, is present in all organisms while they are alive. When they die, their DNA begins to decay under the influence of hydrolysis and oxidation. The speed of this decay varies on a number of factors. Sometimes, the DNA will be gone within one century, and in other conditions, it will persist for as many as one million years. The average amount of time detectable DNA will persist though is somewhere in the middle; given physiological salt concentrations, neutral pH, and a temperature of 15 °C, it would take around 100,000 years for all the DNA in a sample to decay to undetectable levels.
If fossils of the dinosaurs were less than 6,000 years old, detectable fragments of DNA should be present in a sizable percent of dinosaur fossils, especially in the Arctic and Antarctic regions where the decay of DNA can be slowed down 10-25 fold. A claim that soft tissues in a Tyrannosaurus fossil had been recovered in 2005 has since been shown to be mistaken, supporting the idea that dinosaur fossils are extremely old.
 Length of the prehistoric day
Measurements of the Earth's paleorotation rates go back to work by John H. Wells of Cornell University on Devonian (370 mya) corals' growth lines. He discovered that the year then had around 400 days, implying a day length of around 22 hours. Because the rate of change of the rotation of the Earth is relatively predictable—about 0.005 seconds per year—one can calculate the last time a year had 400 days, which was about 370 million years ago (which is also about the same as radiometric dating of the coral). More recent work, however, suggests that the Earth's day was 21.9 ± 0.4 hours long about 620 million years ago, a value derived from studying "tidal rhythmites" of Elatina and Reynella, Australia.
 Lunar retreat
South African rocks studied by geologist Ken Eriksson contain ancient tidal deposits indicating that at some point in the past, the Moon orbited "25-percent closer to Earth than it does today." The distance between the Earth and the Moon is 384,403 kilometers, so for Ken Eriksson's work to fit with a YEC timescale the Earth would have to have been receding at a speed greater than 15 kilometers per year. However, the Moon is currently receding from the Earth at a rate of 3.8 centimeters per year.
More recent work on Precambrian sediments gives more precise numbers. From Neoproterozoic (620 Mya) "tidal rhythmites" in Elatina and Reynella, Australia, the Moon's major axis had a value 0.965 ± 0.005 times its present-day value. That implies an average recession rate of 2.17 ± 0.31 cm/yr, a little more than half the present-day rate of 3.82 ± 0.07 cm/yr. Going back further to banded iron formations in Western Australia in the Paleoproterozoic (2450 Mya), one finds a major-axis ratio of 0.906 ± 0.029, and an average recession rate of 1.24 ± 0.71 cm/yr over most of the Proterozoic. So for whatever reason, the Moon is now outspiraling relatively rapidly, something that makes creationist-style extrapolation of it unjustified.
 Milankovitch astronomical cycles
Milankovitch cycles are cycles of variation of the influx of sunlight, cycles caused by orbit and spin precession effects. Not only does the Earth's spin precess, but also the Earth's orbit. Its perihelion precesses forward and its orbit pole precesses backward, but in complicated quasi-periodic Spirograph patterns that also involve its orbit eccentricity varying. Combined with its spin precession, we have three main kinds of effects:
- Perihelion Precession: over about 20,000 years, the Earth's perihelion time precesses through the seasons.
- Obliquity (Axial Tilt): over about 40,000 years, the Earth's orbit precession makes the Earth's obliquity vary between about 22.1 and 24.5 degrees. It is currently 23.44 degrees and decreasing.
- Eccentricity: over about 100,000 and 400,000 years, the Earth's eccentricity varies from nearly circular to as much as 0.0679 with an average of 0.034. It is currently 0.017 and decreasing.
These variations affect climate by making high-latitude summers sometimes hot, making them melt glaciers fast, and sometimes mild, making them melt glaciers slowly, letting them accumulate over the years. This explains the successful correlation between Milankovitch cycles and continental glaciers' comings and goings during the Pleistocene, the last 2.5 million years.
This work has been extended much further back in time. At first, one might ask if it is possible to do so. But from some calculations, the Earth's spin precession rate has been declining as its rotation rate has declined, but its orbit-precession rates have remained unchanged over at least 500 million years.. In fact, astronomical cycles have been used to improve the timescale from the Oligocene-Miocene boundary to the present. That boundary is now dated at 23.03 million years, to within 40,000 years. It has been more difficult to do that for the earlier Cenozoic, the Mesozoic, and especially the Paleozoic, since good cyclic sedimentary deposits have been more patchy. However, it has been possible to find evidence of astronomical cycles in some 1.4-billion-year-old (mid-Proterozoic) sediments.
 Naica megacrystals
The Naica Mine of Chihuahua, Mexico is the home of some of the largest gypsum crystals on earth. Specimens in the area have been found to exceed 11 meters in length and 1 meter in width. Based on classical crystal growth theory, these crystals are older than one million years.
 Nitrogen impurities in natural diamonds
Nitrogen is the most common impurity in natural diamonds, sometimes by as much as 1% by mass. Recently formed diamonds, however, have very little nitrogen content. A major way synthetic diamonds are distinguished from natural ones is on the basis of nitrogen permeation. It takes long periods and high pressures for the nitrogen atoms to be squeezed into the diamond lattice. Research on the kinetics of the nitrogen aggregation at the University of Reading have suggested that a certain type of diamond, Ia diamonds, spend 200-2000 million years in the upper mantle.
 Oxidizable carbon ratio dating
Oxidizable carbon ratio dating is a method for determining the absolute age of charcoal samples with relative accuracy. This dating method works by measuring the ratio of oxidizable carbon to organic carbon. When the sample is freshly burned, there will be no oxidizable carbon because it has been removed by the combustion process. Over time this will change and the amount of organic carbon will decrease to be replaced by oxidizable carbon at a linear rate. By measuring the ratio of these two allotropes, one can determine ages of over 20,000 years ago with a standard error under 3%.
The formation of permafrost (frozen ground) is a slow process. To be consistent with the young earth creationist model, which states that all sediment was deposited by the global flood, there would have to be absolutely no permafrost present at the end of the flood, because any permafrost that was present at the moment of creation would have been melted during the flood.
Because earth is a good insulator and permafrost forms downward from the surface, it would have taken much more than the few thousand years allotted by creation theory to produce some of the deepest permafrost. In the Prudhoe Bay oil fields of Alaska, the permafrost which extends over 600 meters into the ground is believed to have taken over 225,000 years to reach present depth.
 Petrified wood
The process in which wood is preserved by permineralization, commonly known as petrification, takes extensive amounts of time. Gerald E. Teachout from the South Dakota Department of Game has written that "the mineral replacement process is very slow, probably taking millions of years".
It is true that in the laboratory petrification can be achieved in a matter of months, but petrification is far slower in natural conditions.
 Radioactive decay
Radioactive decay is the constant predictable decay of unstable atoms into more stable isotopes or elements. Measurements of atomic decay are generally considered one of the most accurate ways of measuring the age of an object, and these measurements form the basis for the scientifically accepted age of the Earth. There are many different variations of the radiometric dating technique such as radiocarbon, argon-argon, iodine-xenon, lanthanum-barium, lead-lead, lutetium-hafnium, neon-neon, potassium-argon, rhenium-osmium, rubidium-strontium, samarium-neodymium, uranium-lead, uranium-lead-helium, uranium-thorium, and uranium-uranium, of which every single one will date objects far older than 10,000 years.
Because radiometric dating is one of the most commonly used methods of determining age, these techniques are under constant attack from young earth supporters. A few creationists, armed with only a cursory knowledge and a desire to think that they're better than scientific "experts", may misunderstand radiometric dating and just not believe it works. This is often accompanied by ignoring the high concordance of radiometric methods.
However, the most frequently used method of attack is to give examples of objects of known ages that were dated incorrectly. These instances are by far the exception rather than the rule and are usually due to unforeseen contamination or other errors that can be quickly identified and compensated for. This is not "cheating" and forcing results to conform to expectations as many young earth creationists may claim, it is making the data as accurate and precise as possible (if it is "cheating" then cleaning your camera lens to get a better and clearer picture is also cheating).
 Relativistic jets
A relativistic jet is a jet of plasma that is ejected from some quasars and galaxy centers that have powerful magnetic fields. It is conjectured that the jets are driven by the twisting of magnetic fields in an accretion disk (the plate-like cloud of matter) found encircling many celestial objects. In super-massive bodies, immensely strong magnetic fields force plasma from the accretion disk into a jet that shoots away perpendicular to the face of the disk. In some cases, these columns of plasma have been found to extend far enough to refute the idea of a young universe.
For example, the quasar PKS 1127-145 has a relativistic jet exceeding one million light years in length. Because the speed of light cannot be exceeded, this column must be over one million years old. Moreover, these jets are generally billions of light years from Earth, meaning they were at least a million years old several billion years ago due, again, to the speed of light.
 Rock varnish
Rock varnish is a coating that will form on exposed surface rocks. The varnish is formed as airborne dust accumulates on rock surfaces. This process is extremely slow; between 4 μm and 40 μm of material forms on the rock every thousand years, and instances of 40 μm of accumulation are very rare. Because the rate of accumulation is generally constant, measuring the depth of the varnish can provide dates for objects up to 250,000 years old.
 Seabed plankton layering
Fossils of dead plankton that layer on the ocean floor are used to gauge temperatures from the past, based on the chemical changes of Crenarchaeota, a primitive phylum of microbe. Much like ice layering and dendrochronology, researchers drill through the ocean floor to extract samples which indicate annual temperature fluctuations in the plankton fossils, or "chemical rings" as it were. A 2004 pioneering expedition to the Arctic Ocean near the North Pole collected samples dating back to over 56 million years of temperature dating.
 Sedimentary varves
Varves are laminated layers of sedimentary rock that are most commonly laid down in glacial lakes. In the summer, light colored coarse sediment is laid down, while in the winter, as the water freezes and calms, fine dark silt is laid down. This cycle produces alternating bands of dark and light which are clearly discernible and represent, as a pair, one full year. As is consistent with the old earth view, many millions of varves have been found in some places. The Green River formation in eastern Utah is home to an estimated twenty million years worth of sedimentary layers.
The creationist response is that, instead of once per year, these varves formed many hundreds of times per year. There is, however, much evidence against accelerated formation of varves.
- Pollen in varves is much more concentrated in the upper part of the dark layer, which is thought to represent spring. This is what would be expected if varves formed only once per year because pollen is much more common at this time.
- In Lake Suigetsu, Japan, there is a seasonal die-off of diatoms (calcareous algae) that will form layers in the bottom of the lake along with the sedimentary varves. If the 29 thousand varves in the lake formed more than once per year, there should be several sediment layers for every layer of deceased algae. However, for every one white layer of algae in Lake Suigetsu, there is only one varve.
- The varve thickness in the Green River formation correlates with both the 11 year sunspot cycle and the 21 thousand year orbital cycle of the earth.
 Space weathering
Space weathering is an effect that is observed on most asteroids. Extraterrestrial objects tend to develop a red tint as they age due to the effects of cosmic radiation and micrometeor impacts on their surfaces. Because this process proceeds at a constant rate, observing the color of an object can provide the basis for a generally reliable estimate. The ages provided by this dating technique exceed millions of years.
A stalactite is a mineral deposit that is usually - though not exclusively - found in limestone caves. They are formed on the ceilings of caverns by the slow deposition of calcium carbonate and other minerals as they drip, in solution, over the stalactite. These formations take extremely lengthy periods to form; the average growth rate is not much more than 0.1 mm per year (10 centimetres (4 inches!) per thousand years). With such a slow rate of formation, if the earth was less than ten thousand years old we would expect to see the largest stalactites being not much longer than one metre. In fact stalactites frequently reach from the ceiling to the floor of large caverns.
It is true that cases of accelerated growth have been observed in some stalactites, but rapid growths are only temporary, as the rapidly growing stalactites quickly deplete the surrounding limestone.
 Thermoluminescence dating
Thermoluminescence dating is a method for determining the age of objects containing crystalline minerals, such as ceramics or lava. These materials contain electrons that have been released from their atoms by ambient radiation, but have become trapped by imperfections in the mineral's structure. When one of these minerals is heated, the trapped electrons are discharged and produce light, and that light can be measured and compared with the level of surrounding radiation to establish the amount of time that has passed since the material was last heated (and its trapped electrons were last released).
Although this technique can date objects up to approximately 230,000 years ago, is only accurate on objects 300 to 10,000 years in age. This is, however, still over 4,000 years older than the creationist figure for the age of the earth.
 Uranium-Lead Dating
Uranium-lead dating is based on the idea that because Uranium 235 and Uranium 238 (both common isotopes) turn into lead, and we know how long it takes for both of these isotopes to do so, we can calculate the age of something by comparing the amount of uranium in that something to the amount of lead. Scientists who are dating the Earth commonly use zircons, which are durable and contain trace amounts of uranium. Clair Patterson was the first person to use this technique to figure out the age of the earth, achieving a result very near the current age of 4.54 billion years. Uranium Lead dating has a minimum age of over 700 million years for uranium 235 and 4.5 billion years for uranium 238
 Weathering rinds
Weathering rinds are layers of weathered material that develop on glacial rocks. The weathering is caused by the oxidation of magnesium and iron rich minerals, and the thickness of this layer correlates with the age of a sample. Certain weathering rinds on basalt and andesite rocks in the eastern United States are believed to have taken over 300,000 years to form.
 See also
- Lower limit on the age of the universe
- Radioactive decay
- The incontrovertible evidence for common descent
- Branches of science you have to ignore to believe in Young Earth Creationism
- 101 evidences for a young age of the earth and the universe - a "side by side" rebuttal.
- Chris Stassen (1996). " ".
- ↑ Note: The formation of an entire planet is a process spanning millions of years. Suggesting the earth is 4.54 billion years old does not imply a sudden point of creation — merely that the process that formed the planet began around that time.
- ↑ Kevin R. Henke. "Young-Earth Creationist 'Dating' of a Mt. St. Helens Dacite: The Failure of Austin and Swenson to Recognize Obviously Ancient Minerals". No Answers in Genesis.
- ↑ Michael D. Petraglia, Ravi Korisettar (1998). Early Human Behaviour in Global Context. Routledge Education. Page 63. ISBN 0415117631.
- ↑ Sherriff, Lucy (September 6, 2007). "Dino-killing asteroid traced back 160m years". The Register.
- ↑ Plotner, Tammy (2011). "Did Asteroid Baptistina Kill the Dinosaurs? Think other WISE..." Universe Today.
- ↑ 6.0 6.1 Laurie R. Godfrey (1983). "Scientists Confront Creationism". W. W. Norton & Company, Canada. Pages 35-36. ISBN 0393301540.
- ↑ Manz, Lorraine. Accessed January 21, 2007.
- ↑ Isaak, Mark (2004). "Claim CG010". TalkOrigins. http://www.talkorigins.org/indexcc/CG/CG010.html. Retrieved 2015-01-26.
- ↑  General scientific consensus had been 6 million years, but new research reported 17 million years as the time it took to form
- ↑ The Geologyof the Grand Canyon
- ↑ Why Do People Laugh at Creationists (Part 1)
- ↑ " "(Minnesota state university).
- ↑ Johns, Warren H. (1977). " "(Geoscience Research Institute). Retrieved on September 30, 2007.
- ↑ " " (2007, August 26), from Wikipedia, The Free Encyclopedia. Retrieved 07:37, October 6, 2007.
- ↑ " " (2015, January 5), from Phys.Org)
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- ↑ "An African American paternal lineage adds an extremely ancient root to the human Y chromosome phylogenetic tree". American Journal of Human Genetics 92 (3): 454
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