{"id":800,"date":"2013-04-07T18:51:34","date_gmt":"2013-04-07T23:51:34","guid":{"rendered":"https:\/\/skepticink.com\/smilodonsretreat\/?p=800"},"modified":"2013-04-07T18:51:34","modified_gmt":"2013-04-07T23:51:34","slug":"radiometric-dating-part-ii-isochrons","status":"publish","type":"post","link":"https:\/\/skepticink.com\/smilodonsretreat\/2013\/04\/07\/radiometric-dating-part-ii-isochrons\/","title":{"rendered":"Radiometric Dating &#8211; Part II Isochrons"},"content":{"rendered":"<p>We dealt with the issues around radiocarbon dating <a title=\"Assumptions of Radioactive Dating\" href=\"https:\/\/skepticink.com\/smilodonsretreat\/2013\/04\/05\/assumptions-of-radioactive-dating\/\">here<\/a>. \u00a0That leaves a bunch more to cover.<\/p>\n<blockquote>\n<ul>\n<li>That the atmosphere has had the same (all instead of Carbon 14) concentration in the past as now.\u00a0 Who knows?\u00a0 This is a false assumption. <span style=\"color: #339966\">Done<\/span><\/li>\n<li>That the production of parent isotopes has been constant.\u00a0 Again, who knows?\u00a0 This is a false assumption.<\/li>\n<li>That the original ratio and amounts of the isotope in the fossil or rock is known.\u00a0 This is based on current processes and assumes the rate of absorption was the same in the past.\u00a0 This is a false assumption.<\/li>\n<li>That the decay rate is constant.\u00a0 Many things are known to affect decay rates.\u00a0 This is a false assumption. <span style=\"color: #339966\">Done<\/span><\/li>\n<li>That no contamination has occurred.\u00a0 This is a false assumption.<\/li>\n<li>That no daughter (stable) element was originally in the fossil.\u00a0 This is a false assumption.<\/li>\n<li>That the decay rate was determined accurately.\u00a0 Decay rates are constantly being modified and criticized.\u00a0 This is a false assumption. \u00a0<span style=\"color: #339966\">Done<\/span><\/li>\n<li>That the only loss of the isotope is due to the decay process.\u00a0 This is a false assumption.<\/li>\n<\/ul>\n<\/blockquote>\n<p>Let&#8217;s deal with the rest. \u00a0We can do that, because these are not assumptions. \u00a0These are known issues with radiometric dating and have been dealt with ages ago.<\/p>\n<p>The first radiometric dating of rocks was done in 1907. \u00a0These weren&#8217;t very good because a lot of knowledge about radioactivity really wasn&#8217;t known then. \u00a0But even then, 26 rock samples\u00a0yielded\u00a0dates from 250 million years to 1.3 billion years of age.<\/p>\n<p>The concept of isotopes was discovered in 1913 and it wasn&#8217;t for another 17 years before scientists understood that neutrons were the reason for the difference in isotope mass and what caused certain atomic nuclei to be unstable.<\/p>\n<p>Also in the 30s, geologists finally accepted the use of physics in their field and begun to accept that the age of the Earth was actually a measurable concept.<\/p>\n<p>What about those issues above? \u00a0Well, there are two methods of using radiometric dating that deal with those issues.<\/p>\n<p>The first is exceedingly simple. \u00a0Use multiple testing methods on the same sample. \u00a0If there is a huge problem with one kind of dating or even all of them, then the resulting dates should be all over the place. \u00a0But that&#8217;s not what we see.<\/p>\n<blockquote>\n<table>\n<tbody>\n<tr>\n<th colspan=\"4\" align=\"left\">1. St. Severin (ordinary chondrite)<\/th>\n<\/tr>\n<tr>\n<td width=\"1em\"><\/td>\n<td>1.<\/td>\n<td>Pb-Pb isochron<\/td>\n<td>4.543 \u00b1 0.019 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>2.<\/td>\n<td>Sm-Nd isochron<\/td>\n<td>4.55\u2007 \u00b1 0.33 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>3.<\/td>\n<td>Rb-Sr isochron<\/td>\n<td>4.51\u2007 \u00b1 0.15 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>4.<\/td>\n<td>Re-Os isochron<\/td>\n<td>4.68\u2007 \u00b1 0.15 GY<\/td>\n<\/tr>\n<tr>\n<th colspan=\"4\" align=\"left\">2. Juvinas (basaltic achondrite)<\/th>\n<\/tr>\n<tr>\n<td><\/td>\n<td>1.<\/td>\n<td>Pb-Pb isochron<\/td>\n<td>4.556 \u00b1 0.012 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>2.<\/td>\n<td>Pb-Pb isochron<\/td>\n<td>4.540 \u00b1 0.001 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>3.<\/td>\n<td>Sm-Nd isochron<\/td>\n<td>4.56\u2007 \u00b1 0.08 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>4.<\/td>\n<td>Rb-Sr isochron<\/td>\n<td>4.50\u2007 \u00b1 0.07 GY<\/td>\n<\/tr>\n<tr>\n<th colspan=\"4\" align=\"left\">3. Allende (carbonaceous chondrite)<\/th>\n<\/tr>\n<tr>\n<td><\/td>\n<td>1.<\/td>\n<td>Pb-Pb isochron<\/td>\n<td>4.553 \u00b1 0.004 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>2.<\/td>\n<td>Ar-Ar age spectrum<\/td>\n<td>4.52\u2007 \u00b1 0.02 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>3.<\/td>\n<td>Ar-Ar age spectrum<\/td>\n<td>4.55\u2007 \u00b1 0.03 GY<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>4.<\/td>\n<td>Ar-Ar age spectrum<\/td>\n<td>4.56\u2007 \u00b1 0.05 GY<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/blockquote>\n<blockquote><p>from\u00a0Dalrymple, Brent G. (2004).\u00a0<em>Ancient Earth, Ancient Skies: The Age of the Earth and Its Cosmic Surroundings<\/em>. Stanford University Press. pp.\u00a0147, 169.<\/p><\/blockquote>\n<p>These are radiometric dates from meteorites. \u00a0The first uses lead\/lead dating, samarium\/neodymium dating, rubidium\/strontium dating, and rhenium\/osmium dating. \u00a0Four totally different radiometric methods (and all are isochrons).<\/p>\n<p>If you sit down with some paper and plot the ranges, you&#8217;ll see that all the measured dates overlap between \u00a04.53 GY (billion years) and 4.562 GY. \u00a0 Because of the different natures of each of these radioactive decay sequences, it&#8217;s unlikely that random chance has resulted in 4 totally different dating methods all cover the same range.<\/p>\n<p>The second method is the use of isochrons. \u00a0Here&#8217;s the <a href=\"http:\/\/www.talkorigins.org\/faqs\/isochron-dating.html\">talk.origins FAQ on isochrons<\/a>. \u00a0I&#8217;ll try to summarize.<\/p>\n<p>Basically an isochron is a<\/p>\n<blockquote><p><strong>:<\/strong>\u00a0an imaginary line or a line on a chart connecting points at which an event occurs simultaneously or which represents the same time or time difference (<a href=\"http:\/\/www.merriam-webster.com\/dictionary\/isochron\">M-W online<\/a>)<\/p><\/blockquote>\n<p>Isochron dating&#8217;s only assumption is that we have no idea what the ratios of parent material, and both radioactive and stable daughter material is. \u00a0If this method works, then it neatly dispenses with all of the remaining issues listed by the creationists.<\/p>\n<p>The scientist takes a sample of rock and then examines two main ratios. \u00a0The ratio of the parent isotope and a radiometric daughter isotope and the ratio of the parent isotope to a stable daughter isotope. \u00a0Perhaps I should explain.<\/p>\n<p>When most radioactive elements decay, they do not immediately form a stable atom. \u00a0They generally go through a series of other radioactive isotopes before becoming stable. \u00a0All of these products are called daughters. \u00a0Here&#8217;s the sequence for Thorium-232.<\/p>\n<figure style=\"width: 416px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/1\/1c\/Decay_chain%284n%2CThorium_series%29.PNG\/416px-Decay_chain%284n%2CThorium_series%29.PNG\" alt=\"File:Decay chain(4n,Thorium series).PNG\" width=\"416\" height=\"599\" \/><figcaption class=\"wp-caption-text\">by Tosaka source:Wikimedia commons (http:\/\/en.wikipedia.org\/wiki\/File:Decay_chain(4n,Thorium_series).PNG)<\/figcaption><\/figure>\n<p>In this diagram, the label on the arrows shows the type of decay. \u00a0The time shows is the half-life of that isotope. \u00a0And it is stacked so that the position shows the atomic number of the isotope.<\/p>\n<p>The stable daughter in the thorium series is lead-208 (all paths end up with lead). \u00a0Any other isotope would work for the unstable daughter isotope in an isochron dating test.<\/p>\n<p>The other thing that isochron dating requires is that multiple samples be tested from the same source material. \u00a0This is because, when these ratios are determined, they are plotted on a graph. \u00a0The slope of the line determines the age of material.<\/p>\n<p>Since two points can make a line, we must have more than two points to effectively determine the age. \u00a0The closer all these points are to a straight line, the more accurate the date is.<\/p>\n<p>The isochron method doesn&#8217;t need to determine the amount of parent material. \u00a0There is a mathematical equality between the two ratios determined during the dating process. \u00a0Because of this, the issues of unknown amounts of parent and daughter materials doesn&#8217;t matter. \u00a0This is especially true if you can make multiple tests with multiple radioactive isotopes.<\/p>\n<p>A final note. \u00a0Geologists who work with radiodating methods are well versed in determining if a work could possibly have had leeching of the daughter material out of it. \u00a0This is especially important with potassium argon dating techniques as the daughter material is a gas and can easily escape.<\/p>\n<p>Let me know if I wasn&#8217;t clear about anything. \u00a0Allergy medications sometimes&#8230; influence my writing ability.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>We dealt with the issues around radiocarbon dating here. \u00a0That leaves a bunch more to cover. That the atmosphere has&hellip;<\/p>\n","protected":false},"author":27,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,24,53,6],"tags":[376,375],"class_list":["post-800","post","type-post","status-publish","format-standard","hentry","category-chemistry","category-creationism","category-physics","category-science","tag-isochrons","tag-radiometric-dating"],"_links":{"self":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/posts\/800","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/users\/27"}],"replies":[{"embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/comments?post=800"}],"version-history":[{"count":0,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/posts\/800\/revisions"}],"wp:attachment":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/media?parent=800"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/categories?post=800"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/tags?post=800"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}