Clocks in the Rocks
Lion head in ivory, Kostenki 1. Despite being tiny, this sculpture is realistic and vivacious. Marl soft, chalky limestone , height 15 mm. Kunstkamera, St Petersburg Lion head. Ralph Frenken Source and text: A collection of stone tools from Kostenki 1. Note the classic Kostenki shouldered or tanged point on the extreme right of the middle row of the photo on the right – Don Photo: Vladimir Gorodnjanski Sculptures of mammoths, Kostenki 1. The domed head and sloping back of an adult mammoth is quite distinctive. Marl soft, chalky limestone and red ochre, height left 28 mm, height right 37 mm.
Radiometric dating is a means of determining the “age” of a mineral specimen by determining the relative amounts present of certain radioactive elements. By “age” we mean the elapsed time from when the mineral specimen was formed. Radioactive elements “decay” that is, change into other elements by “half lives. The formula for the fraction remaining is one-half raised to the power given by the number of years divided by the half-life in other words raised to a power equal to the number of half-lives.
Researchers then quantify the number of cells that died with and without argon treatment.
Riddle of the Bones When did they live? Sampling ancient volcanic ash from Hadar, Ethiopia Lucy and other members of her species, Australopithecus afarensis, lived between 3. They are believed to be the most ancient common ancestor , or “stem” species, from which all later hominids sprang. How do we know when they lived? Estimating the age of hominid fossils is usually a painstaking, two-part process, involving both “absolute” and “relative” dating.
A sample of volcanic ash, for instance, can be given an absolute date of 3.
I have just completed the data reduction on a low potassium basalt from the Medicine Lake, California, the basalt of Tionesta. The recent development of small volume low-background noble gas extraction systems and low-background high-sensitivity mass spectrometers have improved our ability to more accurately and precisely date geologic events. However, the dating of Quaternary, low potassium rocks continues to test the limits of the method because of small quantities of radiogenic argon and large atmospheric argon contamination.
In these early studies the vertical succession of sedimentary rocks and structures were used to date geologic units and events relatively.
Marl soft, chalky limestone , height 15 mm.
Ultra-high-vacuum techniques have been incorporated in the argon extraction apparatus and in a new mass spectrometer especially designed for these researches. It is found that, because of these improvements, the radiogenic argon in small and young samples can be measured with precision. Analytical data for a group of rocks and mineral separates from the Yellowknife subprovince of the Canadian Shield are presented. Results show that micas retain more argon than feldspars and that orthoclase feldspars are more retentive than plagioclase feldspars.
Potassium-argon dates for biotites from the region are consistent and in good agreement with earlier age determinations, suggesting that biotite may retain radiogenic argon quantitatively. A very short time for emplacement of the Yellowknife granite series, ranging from hornblende-biotite diorite to muscovite granite, is inferred. Results given for two unseparated granites and a feldspar phenocryst from the Sierra Nevada batholith confirm earlier lead-alpha activity determinations and an age near m.
Data on mica separates from this region are needed, however. Results on a chondrite meteorite specimen of the Forest City Fall, Iowa, confirm to a remarkable degree earlier data on another specimen from another laboratory and thus confirm a potassium-argon age close to m.
Used in fluorescent lights and in welding, this element gets its name from the Greek word for “lazy,” an homage to how little it reacts to form compounds. But in space, argon is made in stars, when a two hydrogen nuclei, or alpha-particles, fuse with silicon The result is the isotope argon Isotopes of an element have varying numbers of neutrons in the nucleus. Though inert, argon is far from rare; it makes up 0.
By Chemicool’s calculations, that translates to 65 trillion metric tons — and the number increases over time as potassium decays.
Silicate rocks, like quartz, are particularly good at trapping electrons.
Space-filling model of argon fluorohydride Argon’s complete octet of electrons indicates full s and p subshells. This full valence shell makes argon very stable and extremely resistant to bonding with other elements. Before , argon and the other noble gases were considered to be chemically inert and unable to form compounds; however, compounds of the heavier noble gases have since been synthesized.
The first argon compound with tungsten pentacarbonyl, W CO 5Ar, was isolated in However it was not widely recognised at that time. This discovery caused the recognition that argon could form weakly bound compounds, even though it was not the first. It forms at pressures between 4. About , tonnes of argon are produced worldwide every year. Because of this, it is used in potassium—argon dating to determine the age of rocks. Cylinders containing argon gas for use in extinguishing fire without damaging server equipment Argon has several desirable properties: Argon is a chemically inert gas.
Argon is the cheapest alternative when nitrogen is not sufficiently inert. Argon has low thermal conductivity. Other noble gases would be equally suitable for most of these applications, but argon is by far the cheapest.
With time, it became apparent that this classification scheme was much too simple. A fourth category, known as spontaneous fission, also had to be added to describe the process by which certain radioactive nuclides decompose into fragments of different weight. Alpha decay is usually restricted to the heavier elements in the periodic table.
This implies that some of them were originally computed using less accurate values, which is similar to Slusher’s point.
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.
This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points. Since there doesn’t seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate.
However, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old. If these dates are correct, this calls the Biblical account of a recent creation of life into question.
After study and discussion of this question, I now believe that the claimed accuracy of radiometric dating methods is a result of a great misunderstanding of the data, and that the various methods hardly ever agree with each other, and often do not agree with the assumed ages of the rocks in which they are found. I believe that there is a great need for this information to be made known, so I am making this article available in the hopes that it will enlighten others who are considering these questions.
See this page in: Hungarian , Russian , Spanish People who ask about carbon 14C dating usually want to know about the radiometric  dating methods that are claimed to give millions and billions of years—carbon dating can only give thousands of years. People wonder how millions of years could be squeezed into the biblical account of history.
What controversy exists in using radioactive dating?
Although the stable isotopes argon and argon make up all but a trace of this element in the universe, the third stable isotope, argon , makes up Argon and argon make up 0. The gas slowly leaks into the atmosphere from the rocks in which it is still being formed. Argon is isolated on a large scale by the fractional distillation of liquid air. It is used in gas-filled electric light bulbs, radio tubes, and Geiger counters.
It also is widely utilized as an inert atmosphere for arc-welding metals, such as aluminum and stainless steel ; for the production and fabrication of metals, such as titanium , zirconium , and uranium ; and for growing crystals of semiconductors , such as silicon and germanium. An electric discharge through argon at low pressure appears pale red and at high pressure, steely blue. The outermost valence shell of argon has eight electrons , making it exceedingly stable and, thus, chemically inert.
Argon atoms do not combine with one another; nor have they been observed to combine chemically with atoms of any other element. Argon atoms have been trapped mechanically in cagelike cavities among molecules of other substances, as in crystals of ice or the organic compound hydroquinone called argon clathrates.