41. Radiometric Dating Gives Unreliable Results - EvoWiki radiometric dating gives unreliable results. From EvoWiki, the Evolution Education Wiki. Claim radiometric dating gives unreliable results. http://www.evowiki.org/wiki.phtml?title=Radiometric_dating_gives_unreliable_resu

42. Paleosols radiometric dating, Paleosols and the Geologic Column Three strikes against Young Earth Creationism by Joe Meert Original Verison Fall 1999, Updated Nov 20 http://baby.indstate.edu/gga/pmag/paleosol.htm

Radiometric Dating, Paleosols and the Geologic Column Three strikes against Young Earth Creationism by Joe Meert Original Verison Fall 1999, Updated Nov 20, 2000 Figure 1: Paleosol located between the 1470 Ma Butler Hill Granite and the Cambrian Lamotte Sandstone. Photo taken by author in Missouri along State Highway 67 FOLLOW THIS LINK

43. Radiometric Dating EARTH SCIENCE LAB radiometric dating. radiometric dating Graphical Method. 1, 736, 1472, 2, 918, 6426, 3, 528, 12144, radiometric dating - Mathematical Method. http://www.bhc.edu/academics/science/harwoodr/Geol101/Labs/radiometric/

defaultStatus="BHC Geology Lab" EARTH SCIENCE LAB Radiometric Dating Radiometric Dating - Graphical Method The purpose of this portion of this exercise is to practice determining radiometric ages using graphical techniques and mathematical techniques. Consult your lab manual and materials for details. Complete columns 1 and 2 in the table below. For example, after one half-life 0.5 of the original parent isotope remains, 0.5 of the sample is now the daughter isotope. After two half-lives 0.25 of the original parent isotope remains, 0.75 of the sample is now the daughter isotope. Complete column 3. Divide the value in column 2 by the value in column 1. Enter the appropriate value in the space provided. Once all values have been entered, check you answers by clicking on Grade Daughter/Parent Ratio. (Note: Only column 3 will be graded) Half-Lives Elapsed 1. Parent Isotope 2. Daughter Isotope 3. Daughter/Parent Ratio For samples 1, 2 and 3 determine the N D /N P ratio in the table below (calculate and enter each value to 2 decimal places - 3.454 is entered as 3.45; 12 is entered as 12.00; All values less than 1 must have a "0" in front of the decimal - 0.35, 0.50, etc.). N P is the number of parent atoms. N

44. Radiometric Dating Methods radiometric dating Methods. Sean D. Pitman MD. © December 2003. History of radiometric dating. Radioactive Parent. Stable Daughter. Half life. Potassium 40. http://naturalselection.0catch.com/Files/Radiometric Dating.html

Radiometric Dating Methods Sean D. Pitman M.D. © December 2003 History of Radiometric Dating Radioactive Parent Stable Daughter Half life Potassium 40 Argon 40 1.25 billion yrs Rubidium 87 Strontium 87 48.8 billion yrs Thorium 232 Lead 208 14 billion years Uranium 235 Lead 207 704 million years Uranium 238 Lead 206 4.47 billion years Carbon 14 Nitrogen 14 5730 years The radioactivity of is unusual, in that two processes take place: b-decay: electron capture: 11.2% At the time that Darwin's On the Origin of Species was published, the earth was "scientifically" determined to be 100 million years old. By 1932, it was found to be 1.6 billion years old. In 1947, science firmly established that the earth was 3.4 billion years old. Finally in 1976, it was discovered that the earth is "really" 4.6 billion years old What happened? The study of geology grew out of field studies associated with mining and engineering during the sixteenth to nineteenth centuries.

45. Capturing The Night: Astrophotography By Andy Weeks PotassiumArgon radiometric dating. Other radiometric dating Techniques. There are over 40 radiometric dating in use today. Can all these techniques be wrong? http://www.nightskypix.com/radiometric.htm

The Age of Life, Radiometric Dating, and Tree Rings By Andy Weeks Introduction Is life younger than 7,000 years as is the claim of Young-Earth Creationists ? Others like some Jehovah’s Witnesses and Bible Students believe that the creative days of Genesis are each 7,000-years in length . Do these conclusions agree with scientific data of our modern day? We will examine the arguments for both the 24-hour creative days as well as 7,000-year creative days. When these have been understood we will cross examine them in the light of scientific evidence and see how long life on our Earth has been here. If the evidence points to less than 23,000 years as Bible Students believe, then we can conclude that the 7,000-year creative day is correct. If the evidence points to less than 7,000-years then we can conclude that the 24-hour creative day is correct and perhaps embrace creationist claims. We will seek to prove that advanced life ahs indeed been around not only for many thousands of years and point even to millions of years. Carbon Radio Dating One way to ascertain out how long life has been on our Earth is through radiometric dating.

46. CalendarHome.com - Radiometric Dating - Calendar Encyclopedia radiometric dating. From Wikipedia, the free encyclopedia. Probably the best known form of radiometric dating is radiocarbon dating, which uses carbon14. http://encyclopedia.calendarhome.com/Radiometric_dating.htm

The Calendar Home Page! The Calendar Store Free Calendars! Calendar Links Radiometric dating From Wikipedia, the free encyclopedia. Radiometric dating is the determination of the date at which materials were formed by analyzing the decay of radioactive isotopes that were incorporated into the material when it was created and which presumably have not diffused out. Probably the best known form of radiometric dating is radiocarbon dating , which uses carbon Rubidum-Strontium dating is also popular. Most materials decay radioactively to some extent, but the decay rates of most are so long that, for all practical purposes, they can be considered inert. The remainder are said to be radioactive . Radioactive materials can decay in any of several ways, emitting either a particle or radiation and changing to a different element or isotope. The decay rate of radioactive materials does not depend on temperature , chemical environment, or similar factors. For dating purposes, the important parameter is the half-life of the reaction - the time it takes for half the material to decay. Half lives of various isotopes vary from microseconds to billions of years. Materials useful for radiometric dating have half lives from a few thousand to a few billion years. Some types of radiometric dating assume that the initial proportions of a radioactive substance and its decay product are known. The decay product should not be a small-molecule gas that can leak out, and must itself have a long enough half life that it will be present in significant amounts. In addition, the initial element and the decay product should not be produced or depleted in significant amounts by other reactions. The procedures used to isolate and analyze the reaction products must be straightforward and reliable.

47. Radiometric Dating - The Numbers Game Volume 4 Spring Edition 2004. radiometric dating The Numbers Game. Rain Makers. Homepage. Cutting Edge radiometric dating The Numbers Game. The Helium Enigma. http://www.creationequation.com/RadiometricDating_TheNumbersGame.htm

Volume #4 Spring Edition 200 Radiometric Dating: The Numbers Game Rain Makers Homepage About this Website Cutting Edge Radiometric Dating: The Numbers Game The Helium Enigma Missing Links, ... 425 Million-Years of Stasis Chimps Not Our Kin 150 million reasons why... Human Brain Surgeon Speaks Evolutionism's Dr. Mastropaolo Superstitious Nonsense Dr. Russ Humphreys Physicist Looks at Earth's Magnetic Field Reality Check Evolutionism's "Flaws" & "Holes" Tampered Evidence, HokieScience Scopes Trial Scoop The Gavel Heard Round the World Hot Links Archives Warren L. Johns, Esq. Scrutinizing Time Measurements " Ultimately, the Darwinian theory of evolution is no more nor less than the great cosmogenic myth of the twentieth century." Michael Denton Jim Croce's 1970's ballad, Time in a Bottle , inspired the romantic dreams of a generation. Earlier in that century of the atom, geochronologists reached deep into the bottle to decipher time, exploring clues hidden in rocks. Isotopes of forms of elements like uranium (U) and potassium (P) undergo radioactive decay to produce daughter elements. Radiometric isotope ratios between parent and daughter elements are analyzed to interpret the ages of rocks. Crowned with the lofty title, "Radiometric Dating," (or "Absolute Dating,") the process resonates authenticity, inspiring confidence.

48. Leibniz-Labor The LeibnizLabor for radiometric dating and Isotope Research was established 1994 at the Christian-Albrechts University in Kiel, Germany. http://www.uni-kiel.de:8080/leibniz/indexe.htm

Leibniz-Labor for Radiometric Dating and Isotope Research Diese Seite gibt es auch in deutscher Sprache The Lab How to find us Description of the lab Telephone and e-Mail list Recent pricelist, datasheets, etc. Job Announcement News What are we doing? The radiocarbon method C-14-AMS dating Conventional C-14 dating Stable isotope measurements Gamma-ray spectroscopy Recent publications Services we offer Institutes at the CAU Institute of Geology and Palaeontology Institute for Ocean Sciences Special Research Project 313 Archeological Institute (German language only) Geomar Other C links Centre for Isotope Research (RUG) National Ocean Sciences AMS Oxford Radiocarbon Accelerator Unit Quaternary Isotope Lab UW ... Radiocarbon Webinfo For questions, comments and corrections of embarrassing errors, please contact: pgrootes@leibniz.uni-kiel.de Last update: November 6th, 2003 (MH)

49. The NSDL Scout Report For Physical Sciences-- Volume 3, Number 5 Topic In Depth. radiometric dating. 1 radiometric dating How do we determine the age of a rock? http//www.dc.peachnet.edu/~pgore http://scout.cs.wisc.edu/Reports/NSDL/PhysSci/2004/ps-040305-topicindepth.php

@import url("ginclude/ScoutPageStructure.css"); @import url("ginclude/ScoutContentStructure.css"); Home The Scout Report Archives Projects ... Feedback Log In: Password: Forget your password? Create a Log In Topic In Depth Printable Page Internet Scout Project NSDL Scout Reports Physical Sciences ... Topic In Depth Radiometric Dating 1 Radiometric Dating: How do we determine the age of a rock? http://www.dc.peachnet.edu/~pgore/geology/geo102/radio.htm 2 Museum Victoria: 2 Radiometric Dating http://www.museum.vic.gov.au/scidiscovery/radioactivity/radio_dating.asp 3 University of Central Arkansas: Radiometric Dating http://faculty.uca.edu/~benw/sci3410/pres/radiometrics/ 4 Tulane University: Radiometric Dating http://www.tulane.edu/~sanelson/eens211/radiometric_dating.htm 5 Marine Reservoir Correction Database http://www.qub.ac.uk/arcpal/marine/ 6 Scottish Universities Research and Reactor Centre http://www.gla.ac.uk/centres/surrc/index.html 7 Countertop Chemistry Experiment 32: Radioactive Decay of Candium http://www.science-house.org/learn/CountertopChem/exp32.html

50. Physical Geology Lecture - Radiometric Dating of NE. radiometric dating internal clocks in rocks. This assumption can be tested for. Systems commonly used for radiometric dating, with half lives. http://maps.unomaha.edu/Maher/geo117/part2/117radiometric.html

Physical Geology (GEOL 1170) Lecture, H. D. Maher Jr., Univ. of NE Radiometric dating - internal clocks in rocks. Geochronology: the science of dating geologic materials. Basics of radioactive decay and isotopic dating. Radioactive decay occurs at an exponential rate, meaning that it can be described in terms of a half life. After one half live, half of the original radioactive isotope material in the system under consideration decays. Another half life and half of the remaining material decays, and so on. This is for unforced decay. Forced decay is when the isotopic material is packed densely enough that a decay in one unstable atom sends out a particle that hits another atom and causes it to decay. If it is packed too densely there is a run away reaction and one of those unpopular mushroom clouds or mneltdowns. Normal concentrations of radioactive material on earth are well below the levels where forced decay occurs so we can use the relatively simple mathematics of exponential decay to describe the process. the rate of decay is constant for earthly P-T conditions. A major assumption is that the rock or mineral being dated has been a closed system so that no parent isotope or daughter product has escaped or been added. This assumption can be tested for.

51. Radiometric Dating radiometric dating. radiometric dating. During the 19th century, and even well into the twentieth, geological chronology was very crude. http://www.palaeos.com/Geochronology/radiometric_dating.htm

Palæos: Geochronology GEOCHRONOLOGY Radiometric Dating Home Palaeont- ology Evolution ... Page Back Unit Back Geochronology Home Geological Time Scale Geochronology Glossary Page Next Unit Next Unit Up References Paleontology Radiometric Dating Geochronology Main Page Historical discovery of the geological timescale Stratigraphy Radiometric dating (you are here) Different Time-Scales Radiometric Dating Carbon-14 Dating Other forms of Radiometric Dating ... Links Different Time-Scales Different world-views have different time-scales as regards the history of the Earth and the universe. Buddhist , Jain and Hindu cosmologies describe the universe as a never-ending series of cycles each lasting millions or billions of years. The Greeks had the "great year" of 24,500 years, based on the precession of the equinoxes. The time-scale of the fundamentalist or Creationist Judeo-Christian is based on a word-for-word reading of the first book of the Bible, and assumes a total age of the earth and the cosmos of a mere 5 or 6,000 (some Creationists allow 10,000) years. Astronomy and Geology, working on scientific data built up over the last two centuries or so, assumes the Earth to be very ancient, more in keeping with the eastern than the western (Graeco-Judeo-Christian) perspectives. However, whereas the

52. Radiometric-for-beginners radiometric dating for Beginners Version 1.0 Copyright © 1999 by Ken Harding last update March 24, 1999 radiometric dating is accurate. http://evolution.mbdojo.com/radiometric-for-beginners.htm

Radiometric Dating for Beginners Version 1.0 Ken Harding [last update: March 24, 1999] here is one important factor on which the theory of evolution depends: for evolution to take place, hundreds of millions of years must pass, and so the earth has to be very ancient. This is one idea that creationists must attack, both for the need to undermine evolutionary biology, and for the need to support the literalist interpretation of the biblical age of around 6000 years. Therefore, not only does biology come under creationist attack, but so does the science of geology. One of the most frequent criticisms from creationists is the criticism of Radiometric Dating methods- the means by which we know that the earth is incredibly old. The fact that radiometric dating is so far beyond the average person's level of scientific education is leverage for the creationists. Most people simply don't have the training to understand the topic. The casual dropping of unsubstantiated statements like “Radiometric dating is full of errors and is unreliable” is an all-too-frequent tactic of creationists that their followers instantly buy into. Check into what creationists say before accepting their statements at face value! Radiometric dating is accurate. But don't take my word for it. Christians who are not biblical literalists are actively engaged in science which promotes radiometric dating. Listen to the

53. Radiometric Dating radiometric dating. Probably the best known form of radiometric dating is radiocarbon dating, which uses carbon14. Rubidum-Strontium dating is also popular. http://www.fact-index.com/r/ra/radiometric_dating.html

Main Page See live article Alphabetical index Radiometric dating Radiometric dating is the determination of the date at which materials were formed by analyzing the decay of radioactive isotopes that were incorporated into the material when it was created and which presumably have not diffused out. Probably the best known form of radiometric dating is radiocarbon dating , which uses carbon Rubidum-Strontium dating is also popular. Most materials decay radioactively to some extent, but the decay rates of most are so long that, for all practical purposes, they can be considered inert. The remainder are said to be radioactive . Radioactive materials can decay in any of several ways, emitting either a particle or radiation and changing to a different element or isotope. The decay rate of radioactive materials does not depend on temperature , chemical environment, or similar factors. For dating purposes, the important parameter is the half-life of the reaction - the time it takes for half the material to decay. Half lives of various isotopes vary from microseconds to billions of years. Materials useful for radiometric dating have half lives from a few thousand to a few billion years. Some types of radiometric dating assume that the initial proportions of a radioactive substance and its decay product are known. The decay product should not be a small-molecule gas that can leak out, and must itself have a long enough half life that it will be present in significant amounts. In addition, the initial element and the decay product should not be produced or depleted in significant amounts by other reactions. The procedures used to isolate and analyze the reaction products must be straightforward and reliable.

54. How Do Geologists Date Rocks? Radiometric Dating How do geologists date rocks? radiometric dating! A commonly used radiometric dating technique relies on the breakdown of potassium ( 40 K) to argon ( 40 Ar). http://wrgis.wr.usgs.gov/docs/parks/gtime/radiom.html

How do geologists date rocks? Radiometric dating! Radioactive elements were incorporated into the Earth when the Solar System formed. All rocks and minerals contain tiny amounts of these radioactive elements. Radioactive elements are unstable; they breakdown spontaneously into more stable atoms over time, a process known as radioactive decay. Radioactive decay occurs at a constant rate, specific to each radioactive isotope . Since the 1950s, geologists have used radioactive elements as natural "clocks" for determining numerical ages of certain types of rocks. Radiometric clocks are "set" when each rock forms. "Forms" means the moment an igneous rock solidifies from magma, a sedimentary rock layer is deposited, or a rock heated by metamorphism cools off. It's this resetting process that gives us the ability to date rocks that formed at different times in earth history. A commonly used radiometric dating technique relies on the breakdown of potassium ( K) to argon ( Ar). In igneous rocks, the potassium-argon "clock" is set the moment the rock first crystallizes from magma. Precise measurements of the amount of

55. === Radiometric Dating === Home / dating / radiometric dating. The best information on radiometric dating can be found at these sites. radiometric datingthe process of determining http://www.dating-singles-action.com/dating/radiometric_dating.htm

Singles Dating Directory Asian Brides Dating Mail Order Brides Marriage ... radiometric dating The best information on radiometric dating can be found at these sites Radiometric Dating Radiometric Dating How do we determine the age of a rock? Relative ... than B" Absolute dating Quantify the date in years. Radiometric Dating Principles of Radiometric Dating Naturally-occurring radioactive materials break down ... Educational materials on the topic. http://www.dc.peachnet.edu/~pgore/geology/geo102/radio.htm 9 A Radiometric Dating Resource List A Radiometric Dating Resource List updated & links checked ... debate" is the right word) is always radiometric dating. There are lots of ways to guesstimate ... But they didn't know how old. Radiometric dating actually allows the measurement ... Large annotated directory of internet resources on radiocarbon and other radioactive dating methods, including creationists' views and scientific critiques of those views. http://www.tim-thompson.com/radiometric.html Geologic Time: Radiometric Time Scale RADIOMETRIC TIME SCALE The discovery ... Earth materials. Precise dating has been accomplished since ... shale are related to the radiometric time scale by bracketing ... zones that are determined by dating appropriately selected igneous ... Discusses the uses of limitations of different radiometric dating techniques.

56. The Unreliability Of Radiometric Dating Beta version this article is being revised and updated. The Unreliability of radiometric dating By Jon Covey, BA, MT(ASCP) Edited by Anita Millen, MD, MPH, MA. http://www.creationinthecrossfire.com/documents/Radiomentric Dating/Radiometric

Beta version: this article is being revised and updated. The Unreliability of Radiometric Dating By Jon Covey, B.A., MT(ASCP) Edited by Anita Millen, M.D., M.P.H., M.A. Most people, including scientists, assume that radioactive dating methods, such as Carbon-14 or Uranium, are very reliable. Because of this, they view young earth creationists as foolish—akin to those who believe in a flat earth. Many think all one has to do to date a rock is put it into a machine, then the machine will count the radioactive decay incidents and convert it into a date we can understand. Few people are aware of the assumptions that must be made and the widely differing dates that can be obtained from samples of the same rock, vastly older or younger than the "accepted" age of the rock based on the fossil record of the geological layer from which it came. Philosophical predisposition, whether creationist or evolutionist, determines the assumptions made. Most people, including most scientists, are unaware of the pitfalls in the radiometric dating methods. The Young-Earth View Died with Lord Kelvin The Encyclopaedia Britannica (1997 CD-ROM) gave this account: Age of the Earth , Harold Slusher and Thomas Gamwell reexamined the time required for the earth cooling to its present temperature. They made five calculations for the cooling time based on a range of estimates, starting with presently known stores of radioactive materials in the earth. They concluded that even with unrealistically high estimates the earth could not have been cooling for more than one billion years. [Slusher]

57. The Unreliability Of Radiometric Dating The Unreliability of radiometric dating. Most people, including most scientists, are unaware of the pitfalls in the radiometric dating methods. http://www.creationinthecrossfire.com/Articles/Radiometric Dating.html

The Unreliability of Radiometric Dating By Jon Covey, B.A., MT(ASCP) Edited by Anita Millen, M.D., M.P.H., M.A. Most people, including scientists, assume that radioactive dating methods, such as Carbon-14 or Uranium, are very reliable. Because of this, they view young earth creationists as foolish—akin to those who believe in a flat earth. Many think all one has to do to date a rock is put it into a machine, then the machine will count the radioactive decay incidents and convert it into a date we can understand. Few people are aware of the assumptions that must be made and the widely differing dates that can be obtained from samples of the same rock, vastly older or younger than the "accepted" age of the rock based on the fossil record of the geological layer from which it came. Philosophical predisposition, whether creationist or evolutionist, determines the assumptions made. Most people, including most scientists, are unaware of the pitfalls in the radiometric dating methods. The Young-Earth View Died with Lord Kelvin The Encyclopaedia Britannica (1997 CD-ROM) gave this account: Age of the Earth , Harold Slusher and Thomas Gamwell reexamined the time required for the earth cooling to its present temperature. They made five calculations for the cooling time based on a range of estimates, starting with presently known stores of radioactive materials in the earth. They concluded that even with unrealistically high estimates the earth could not have been cooling for more than one billion years. [Slusher]

58. One Of The Main Objections To Radiometric Dating One of the main objections to radiometric dating (on the part of young earth creationists) is that radiometric ages do not agree with each other or that http://gondwanaresearch.com/radiomet.htm

Consistent Radiometric dates by Joe Meert Created Jan 2000 Updated January 6, 2004 (links fixed, added) O ne of the main objections to radiometric dating (on the part of young earth creationists) is that radiometric ages do not agree with each other or that contamination renders ages meaningless. In fact, the claim is partially true. Early mass spectrometers were not as sensitive as machines today and the methods for separating, cleaning and analysis were less sophisticated. Although ye-creationists like Snelling talk about contamination of isotopic systems as if it were a foreign concept to modern geology, most geochronologists a Rock/Location Method Age +/- Error Reference 1. Fen Complex, Norway-A Ar/ Ar 588 +/- 10 Ma Meert et al, 1998 2. Fen Complex, Norway-B Ar/ Ar 578 +/- 10 Ma Meert et al., 1998 3. Fen complex, Norway K-Ar whole rock 575 +/- 25 Ma (average) Verschure et al., 1983 4. Fen Complex, Norway Rb-Sr isochron (phlogopite) 578 +/- 24 Ma Dahlgren, 1994

59. Paleosols radiometric dating, Paleosols and the Geologic Column Three strikes against Young Earth Creationism by Joe Meert Original Verison Fall 1999, Updated November http://gondwanaresearch.com/hp/paleosol.htm

Radiometric Dating, Paleosols and the Geologic Column Three strikes against Young Earth Creationism by Joe Meert Original Verison Fall 1999, Updated November 2003 Figure 1 : Paleosol located between the 1470 Ma Butler Hill Granite and the Cambrian Lamotte Sandstone. Photo taken by author in Missouri along State Highway 67. The weathered granite is overlain by a shaly regolith and the Lamotte sandstone overlaps this irregular surface. This photo is updated as the old photo was improperly formatted (the update was made solely to provide proper perspective and to highlight the absurdity of Tas Walker's 'analysis' rather than to Walker's blustering about 'changing the story'). Also shown below (click for a larger version) is a photo of the paleosol taken from the other side of the road. Figure 2: Click to enlarge. 100 dpi photo of the same outcrop taken from the opposite side of the road showing from bottom to top (regolith of Butler Hill Granite, dark paleosol formed on top of the granite, shaly Lamotte Formation (basal), Lamotte sandstone (top). A geologist hammer is shown for scale. Photo courtesy E. Kisvarsanyi et al. TAS WALKER'S BLUNDER FROM THE ANTIPODES DISCUSSED HERE here are several concepts in Geology that are anathema to young-earth (ye) creationism because they pose such a difficult problem for the concept of a young earth. The collective observations from:

60. Radiometric Dating - Reference Library radiometric dating. Probably the best known form of radiometric dating is radiocarbon dating, which uses carbon14. Rubidum-Strontium dating is also popular. http://www.campusprogram.com/reference/en/wikipedia/r/ra/radiometric_dating.html

Reference Library: Encyclopedia Main Page See live article Alphabetical index Radiometric dating Radiometric dating is the determination of the date at which materials were formed by analyzing the decay of radioactive isotopes that were incorporated into the material when it was created and which presumably have not diffused out. Probably the best known form of radiometric dating is radiocarbon dating , which uses carbon Rubidum-Strontium dating is also popular. Most materials decay radioactively to some extent, but the decay rates of most are so long that, for all practical purposes, they can be considered inert. The remainder are said to be radioactive . Radioactive materials can decay in any of several ways, emitting either a particle or radiation and changing to a different element or isotope. The decay rate of radioactive materials does not depend on temperature , chemical environment, or similar factors. For dating purposes, the important parameter is the half-life of the reaction - the time it takes for half the material to decay. Half lives of various isotopes vary from microseconds to billions of years. Materials useful for radiometric dating have half lives from a few thousand to a few billion years. Some types of radiometric dating assume that the initial proportions of a radioactive substance and its decay product are known. The decay product should not be a small-molecule gas that can leak out, and must itself have a long enough half life that it will be present in significant amounts. In addition, the initial element and the decay product should not be produced or depleted in significant amounts by other reactions. The procedures used to isolate and analyze the reaction products must be straightforward and reliable.

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