Exponential and logarithmic functions, algebraic operations, graphs Age of the Earth: Introduction How can we tell how old the Earth is? Certain natural phenomena or processes, such as Earth’s year-long solar orbit, and the resulting annual climatic variations that govern the growth of tree rings, can be used as “natural clocks. Can we find in rocks a natural clock that has been operating since they formed? It was discovered that some chemical elements, notably uranium and thorium, are strongly radioactive. These elements occur naturally in nearly all rocks, and they account for the radioactivity you could observe with a Geiger counter. The radioactive decay process can be described simply as the transformation of an unstable radioactive atom called the parent to a new atom called the daughter that may differ in atomic number, atomic mass, or both. The transformation occurs either by loss of particles from, or addition of particles to, the parent nucleus. In some parent-daughter pairs, the daughter is still radioactive and subject to further decay to a new daughter.
Dinosaurs disappeared about 65 million years ago. That corn cob found in an ancient Native American fire pit is 1, years old. How do scientists actually know these ages? Geologic age dating—assigning an age to materials—is an entire discipline of its own. In a way this field, called geochronology, is some of the purest detective work earth scientists do.
The generally accepted age for the Earth and the rest of the solar system is about billion years (plus or minus about 1%). This value is derived from several.
Relative dating Studies of strata , the layering of rocks and earth, gave naturalists an appreciation that Earth may have been through many changes during its existence. These layers often contained fossilized remains of unknown creatures, leading some to interpret a progression of organisms from layer to layer. Lomonosov’s ideas were mostly speculative. In the Comte du Buffon tried to obtain a value for the age of Earth using an experiment: He created a small globe that resembled Earth in composition and then measured its rate of cooling.
This led him to estimate that Earth was about 75, years old. Other naturalists used these hypotheses to construct a history of Earth , though their timelines were inexact as they did not know how long it took to lay down stratigraphic layers. This was a challenge to the traditional view, which saw the history of Earth as static,[ citation needed ] with changes brought about by intermittent catastrophes.
Many naturalists were influenced by Lyell to become “uniformitarians” who believed that changes were constant and uniform. His calculations did not account for heat produced via radioactive decay a process then unknown to science or, more significantly, convection inside the Earth, which allows more heat to escape from the interior to warm rocks near the surface.
Can we use radioactive carbon dating to determine the age of the earth? The answer is no, we can’t. The reason is twofold.
The age of billion years found for the Solar System and Earth is consistent with current calculations of 11 to 13 billion years for the age of the Milky Way Galaxy (based on the stage of evolution of globular cluster stars) and the age of 10 to 15 billion years for the age of the Universe (based on the recession of distant galaxies).
General considerations Distinctions between relative-age and absolute-age measurements Local relationships on a single outcrop or archaeological site can often be interpreted to deduce the sequence in which the materials were assembled. This then can be used to deduce the sequence of events and processes that took place or the history of that brief period of time as recorded in the rocks or soil. For example, the presence of recycled bricks at an archaeological site indicates the sequence in which the structures were built.
Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence. Although with clever detective work many complex time sequences or relative ages can be deduced, the ability to show that objects at two separated sites were formed at the same time requires additional information.
A coin, vessel, or other common artifact could link two archaeological sites, but the possibility of recycling would have to be considered. It should be emphasized that linking sites together is essential if the nature of an ancient society is to be understood, as the information at a single location may be relatively insignificant by itself. Similarly, in geologic studies, vast quantities of information from widely spaced outcrops have to be integrated.
Some method of correlating rock units must be found. In the ideal case, the geologist will discover a single rock unit with a unique collection of easily observed attributes called a marker horizon that can be found at widely spaced localities. Any feature, including colour variations, textures, fossil content, mineralogy , or any unusual combinations of these can be used. It is only by correlations that the conditions on different parts of Earth at any particular stage in its history can be deduced.
For example, back in , Lord Kelvin calculated how long Earth might have taken to cool from its original molten state. He concluded that Earth was born 20 to million years ago. Their message proved difficult to decipher. How old is Earth? However, from working with layer upon layer of rock laid down on Earth over long time spans, early 20th century scientists came to believe Earth not millions of years old — but billions of years old.
Florian Cajori, author of the article “The Age of the Sun and the Earth,” was a historian of science and, especially, of mathematics, and Ray Lankester, whom he quotes, was a zoologist. H. N.
The stable form of carbon is carbon 12 and the radioactive isotope carbon 14 decays over time into nitrogen 14 and other particles. Carbon is naturally in all living organisms and is replenished in the tissues by eating other organisms or by breathing air that contains carbon. At any particular time all living organisms have approximately the same ratio of carbon 12 to carbon 14 in their tissues.
When an organism dies it ceases to replenish carbon in its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon Experts can compare the ratio of carbon 12 to carbon 14 in dead material to the ratio when the organism was alive to estimate the date of its death. Radiocarbon dating can be used on samples of bone, cloth, wood and plant fibers. The half-life of a radioactive isotope describes the amount of time that it takes half of the isotope in a sample to decay.
In the case of radiocarbon dating, the half-life of carbon 14 is 5, years. This half life is a relatively small number, which means that carbon 14 dating is not particularly helpful for very recent deaths and deaths more than 50, years ago. After 5, years, the amount of carbon 14 left in the body is half of the original amount. If the amount of carbon 14 is halved every 5, years, it will not take very long to reach an amount that is too small to analyze.
Dating Here of some of the well-tested methods of dating used in the study of early humans: Potassium-argon dating, Argon-argon dating, Carbon or Radiocarbon , and Uranium series. All of these methods measure the amount of radioactive decay of chemical elements; the decay occurs in a consistent manner, like a clock, over long periods of time.
In the s, Earth’s age crept up toward 3 billion years, making it for a time even older than the universe, which was then estimated to be about billion years old.
Tools are objects that make our lives easier. A computer or smart phone are examples of modern-day tools. Paleolithic is a word that comes from the two Greek words palaios, meaning old, and lithos, meaning stone. Using a hammer stone for flaking. Which stone do you think is harder, the object stone, or the hammer stone? The first stone tools were used to meet people’s three basic needs of food, shelter, and clothing. These were difficult times; there were no stores to buy food, and people had to cooperate in small groups to make clothing and shelter.
To hunt for food, early humans formed spears, first by sharpening the ends of sticks, but later by attaching a sharp stone spear-tip to wood using animal sinew. A tool made up of more than one material is called a composite tool. Flaking was one of the first uses of technology. Technologies are tools and also skills that make our lives easier. Flaking involves using a hammer stone to form sharp edges on an object stone by striking it on its sides.
The Radiometric Dating Game Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium. On the surface, radiometric dating methods appear to give powerful support to the statement that life has existed on the earth for hundreds of millions, even billions, of years.
We are told that these methods are accurate to a few percent, and that there are many different methods. We are told that of all the radiometric dates that are measured, only a few percent are anomalous.
Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, including the age of fossilized life forms or the age of the Earth itself, and can also be used to date a wide range of natural and man-made materials.
The Oldest Living Thing: The oldest living thing on earth is either an Irish Oak or a Bristlecone pine. If we assume a growth rate of one tree ring per year, then the oldest trees are between 4, and 4, years old. Also, with regard to fossil tree rings, the author has been unable to find any documented instances of fossil trees having more than about rings.
This is significant since we are told that God literally made the Earth, and all that is in it, only about years before the Noachian Flood described in the Book of Genesis. In a Bristlecone Pine tree was discovered that has just over 5, tree rings. Helium in the Atmosphere: Helium is a byproduct of the radioactive decay of uranium as it decays into various different elements into its final stable element: As it decays, the helium not only accumulates in the rocks themselves, but also escapes from them and accumulates in the earth’s atmosphere.
They also know how much helium is currently in the atmosphere. If we use the same assumptions that radiometric dating experts make: