How Science Figured Out the Age of Earth

David H. Bailey does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment. In one respect, science and religion have been largely reconciled since the 19th century, when geologists such as Charles Lyell recognised the evidence for a very old Earth. Within a few decades, most mainstream religious denominations accepted this view as well. But, much to the consternation of scientists, young-Earth creationism , which holds Earth is only about 6, years old, continues to be promoted in some quarters, and remains very popular with the public, especially in the United States. By contrast, and more representative of OECD countries, only about half as many Canadians espouse such beliefs. Such notions, of course, differ vastly to the findings of modern science, which pegs the age of the earth at 4. While there are numerous experimental methods used to determine geologic ages, the most frequently employed technique is radiometric dating , based on measurements of various radioactive isotopes in rocks. The phenomenon of radioactivity is rooted in the fundamental laws of physics and follows simple mathematical formulae, taught to all calculus students. Dating schemes based on rates of radioactivity have been refined and scrutinised over several decades, and the latest high-tech equipment permits reliable results to be obtained even with microscopic rock samples.

How Do Scientists Measure Earth Age?

An Essay on Radiometric Dating. Radiometric dating methods are the strongest direct evidence that geologists have for the age of the Earth. All these methods point to Earth being very, very old — several billions of years old. Young-Earth creationists — that is, creationists who believe that Earth is no more than 10, years old — are fond of attacking radiometric dating methods as being full of inaccuracies and riddled with sources of error.

Mesozoic bone consistently yields a falsely young radiocarbon “date” of a few thousand Taking advantage of the popularity of dinosaurs, young-Earth However, corrective calibration techniques and other procedures can.

You may have heard that the Earth is 4. This was calculated by taking precise measurements of things in the dirt and in meteorites and using the principles of radioactive decay to determine an age. This page will show you how that was done. Radioactive nuclides decay with a half-life. If the half-life of a material is years and you have 1 kg of it, years from now you will only have 0. The rest will have decayed into a different nuclide called a daughter nuclide. Several radioactive nuclides exist in nature with half-lives long enough to be useful for geologic dating.

This nuclide decays to Strontium Sr87 with a half-life of Imagine going way back in time and looking at some lava that is cooling to become a rock. This is shown schematically in Figure 1. At this point, its radiometric clock starts ticking. Figure 1.

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As has been seen, the geologic time scale is based on stratified rock assemblages that contain a fossil record. For the most part, these fossils allow various forms of information from the rock succession to be viewed in terms of their relative position in the sequence. Approximately the first 87 percent of Earth history occurred before the evolutionary development of shell-bearing organisms.

The result of this mineralogic control on the preservability of organic remains in the rock record is that the geologic time scale—essentially a measure of biologic changes through time—takes in only the last 13 percent of Earth history. Although the span of time preceding the Cambrian period—the Precambrian —is nearly devoid of characteristic fossil remains and coincides with some of the primary rocks of certain early workers, it must, nevertheless, be evaluated in its temporal context.

Zircon Chronology: Dating the Oldest Material on Earth of Florida are expert practitioners of several techniques that can extract precise age information from zircons. He goes on to explain that there are two ways to tell time in geology.

Since the early twentieth century scientists have found ways to accurately measure geological time. The discovery of radioactivity in uranium by the French physicist, Henri Becquerel , in paved the way of measuring absolute time. Shortly after Becquerel’s find, Marie Curie , a French chemist, isolated another highly radioactive element, radium. The realisation that radioactive materials emit rays indicated a constant change of those materials from one element to another.

The New Zealand physicist Ernest Rutherford , suggested in that the exact age of a rock could be measured by means of radioactivity. For the first time he was able to exactly measure the age of a uranium mineral. When Rutherford announced his findings it soon became clear that Earth is millions of years old. These scientists and many more after them discovered that atoms of uranium, radium and several other radioactive materials are unstable and disintegrate spontaneously and consistently forming atoms of different elements and emitting radiation, a form of energy in the process.

Compare and contrast relative age dating and radiometric dating

Earth is about 4. Geologists divide this age into major and minor units of time that describe the kinds of geological processes and life forms that existed in them. Earth’s geologic record was formed by constant change, just like those that occur routinely today. Though some events were catastrophic, much of Earth’s geology was influenced by normal weather, erosion, and other processes spread over very long geologic ages.

Accurate dating of the geologic ages is fundamental to the study of geology and paleontology, and provides important context to the life sciences, meteorology, oceanography, geophysics, and hydrology.

Geologists generally know the age of a rock by determining the age of the group of rocks, Relative dating techniques provide geologists abundant evidence of the January 1 Earth formed; April 7 Life (bacteria and blue-green algae) first.

Your email address is used to log in and will not be shared or sold. Read our privacy policy. If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition. Sign up for our email newsletter for the latest science news. The good dates are confirmed using at least two different methods, ideally involving multiple independent labs for each method to cross-check results.

Sometimes only one method is possible, reducing the confidence researchers have in the results. Kidding aside, dating a find is crucial for understanding its significance and relation to other fossils or artifacts. Methods fall into one of two categories: relative or absolute.

How Do Scientists Date Fossils?

Planet Earth doesn’t have a birth certificate to record its formation, which means scientists spent hundreds of years struggling to determine the age of the planet. So, just how old is Earth? By dating the rocks in Earth’s ever-changing crust, as well as the rocks in Earth’s neighbors, such as the moon and visiting meteorites, scientists have calculated that Earth is 4. Related: How Big is Earth?

With the help of new physical and chemical dating methods, scientists are finally beginning to discover how and when archaic species became well, us.

How Old is That Rock? How can you tell the age of a rock or to which geologic time period it belongs? One way is to look at any fossils the rock may contain. If any of the fossils are unique to one of the geologic time periods, then the rock was formed during that particular time period. Another way is to use the “What’s on top? When you find layers of rocks in a cliff or hillside, younger rocks are on top of older rocks.

But these two methods only give the relative age of rocks–which are younger and which are older. How do we find out how old a rock is in years? Or how do we know how long ago a particular group of fossilized creatures lived? The age of a rock in years is called its absolute age. Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock. When rocks are formed, small amounts of radioactive elements usually get included. As time passes, the “parent” radioactive elements change at a regular rate into non-radioactive “daughter” elements.

Dating: an analytical task

When paleontologist Mary Schweitzer found soft tissue in a Tyrannosaurus rex fossil , her discovery raised an obvious question — how the tissue could have survived so long? The bone was 68 million years old, and conventional wisdom about fossilization is that all soft tissue, from blood to brains , decomposes. Only hard parts, like bones and teeth, can become fossils. But for some people, the discovery raised a different question. How do scientists know the bones are really 68 million years old?

Today’s knowledge of fossil ages comes primarily from radiometric dating , also known as radioactive dating.

For Wagner [7], absolute methods are those allowing to fix the age of an The deep ocean contains the majority ( %) of the Earth carbon.

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FOSSILS: how fossils are dated