What is radiometric dating and how is it used

Radiometric Dating: Methods, Uses & the Significance of Half-Life

What is radiometric dating and how is it used

no — it is the result of extremely careful analyses using a technique that works. three-part series will help you properly understand radiometric dating, the assumptions that lead to inaccurate dates, and the clues about what really happened in the past. isotopes are commonly portrayed as providing rock-solid evidence that the earth is billions of years old. not only that, they have to show the flaws in those dating studies that provide independent corroborative evidence that radiometric methods work. these ash beds, called bentonites, contain sanidine feldspar and biotite that has been dated using the 40ar/39ar technique. third, the radiometric ages agree, within analytical error, with the relative positions of the dated ash beds as determined by the geologic mapping and the fossil assemblages; that is, the ages get older from top to bottom as they should. dating is often used to “prove” rocks are millions of years old. in genesis is an apologetics ministry, dedicated to helping christians defend their faith and proclaim the gospel of jesus christ. this pretty much eliminates any significant laboratory biases or any major analytical mistakes. the40ar/39ar isochron method used by the berkeley scientists, however, does not require any assumptions about the composition of the argon trapped in the rock when it formed — it may be atmospheric or any other composition for that matter. follow the links below to learn more about radiocarbon dating. if you ever wondered why nuclear tests are now performed underground, this is why. the first is that each meteorite was dated by more than one laboratory — allende by 2 laboratories, guarena by 2 laboratories, and st severin by four laboratories. the k-t tektites were ejected into the atmosphere and deposited some distance away. the fallout from this enormous impact, including shocked quartz and high concentrations of the element iridium, has been found in sedimentary rocks at more than 100 locations worldwide at the precise stratigraphic location of the cretaceous-tertiary (k-t) boundary (alvarez and asaro 1990; alvarez 1998). nucleus contains protons (tiny particles each with a single positive electric charge) and neutrons (particles without any electric charge). scientists have concluded that it is not; it is instead a consequence of the fact that radiometric dating actually works and works quite well.

Radiometric dating - Wikipedia

How do geologists date rocks? Radiometric dating!

where are the data and age calculations that result in a consistent set of ages for all rocks on earth, as well as those from the moon and the meteorites, no greater than 10 000 years? and yet, they all give the same result to within a few percent. it will probably fail, but what would a reasonable person conclude from that? first, it provides no evidence whatsoever to support their claim that the earth is very young. observations give us confidence that radiometric dating is not trustworthy., various radioisotope methods or even various attempts using the same method yield discordant ages more often than concordant ages. the ratio of these carbon isotopes reveals the ages of some of earth’s oldest inhabitants. the daughter atoms are not lesser in quality than the parent atoms from which they were produced. in 1997 a team of scientists from the berkeley geochronology center and the university of naples decided to see if the40ar/39ar method of radiometric dating could accurately measure the age of this very young (by geological standards) volcanic material. second, the radiometric age measurements, 187 of them, were made on 3 different minerals and on glass by 3 distinctly different dating methods (k-ar and 40ar/39ar are technical variations that use the same parent-daughter decay scheme), each involving different elements with different half-lives. scientists from the us geological survey were the first to obtain radiometric ages for the tektites and laboratories in berkeley, stanford, canada, and france soon followed suit. each atom is thought to be made up of three basic parts. 40ar/39ar age spectra and total-fusion ages of tektites from cretaceous-tertiary boundary sedimentary rocks in the beloc formation, haiti. so, in general, few people quarrel with the resulting chemical analyses. dating is a technique used by scientists to learn the ages of biological specimens – for example, wooden archaeological artifacts or ancient human remains – from the distant past. is the interpretation of these chemical analyses that raises potential problems. usually determinations of age are repeated to avoid laboratory errors, are obtained on more than one rock unit or more than one mineral from a rock unit in order to provide a cross-check, or are evaluated using other geologic information that can be used to test and corroborate the radiometric ages.

Radiometric Dating | The Institute for Creation Research

 research has even identified precisely where radioisotope dating went wrong. orbiting around the nucleus are electrons (tiny particles each with a single negative electric charge). if the earth were only 6000–10 000 years old, then surely there should be some scientific evidence to confirm that hypothesis; yet the creationists have produced not a shred of it so far. carbon-14 dating: what does it really tell us about the age of the earth? we know the exact day of this eruption because pliny the younger carefully recorded the event. the majority of flows, however, had no detectable excess 40ar and thus gave correct ages as expected. they helped underpin belief in vast ages and had largely gone unchallenged. at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in earth’s atmosphere. austin (1996) has documented excess 40ar in the 1986 dacite flow from mount st helens, but the amounts are insufficient to produce significant errors in all but the youngest rocks. purpose of this paper is to describe briefly a few typical radiometric dating studies, out of hundreds of possible examples documented in the scientific literature, in which the ages are validated by other available information. atoms of each element may vary slightly in the numbers of neutrons within their nuclei. addition to shocked quartz grains and high concentrations of iridium, the k-t impact produced tektites, which are small glass spherules that form from rock that is instantaneously melted by a large impact. thank chris stassen and 2 anonymous reviewers for their thoughtful comments, which led to important improvements in the manuscript. i have selected four examples from recent literature, mostly studies involving my work and that of a few close colleagues because it was easy to do so. excess argon within mineral concentrates from the new dacite lava dome at mount st helens volcano.-14 is an unstable isotope of carbon that will eventually decay at a known rate to become carbon-12. the boundary between these periods (the k-t boundary) is marked by an abrupt change in fossils found in sedimentary rocks worldwide.

How Does Radiocarbon Dating Work? - Instant Egghead #28

other creationists have focused on instances in which radiometric dating seems to yield incorrect results. first, each age is based on numerous measurements; laboratory errors, had there been any, would be readily apparent. do scientists determine the age of fossils that have been under the surface of the earth for thousands of years? if radiometric dating didn’t work then such beautifully consistent results would not be possible. first, the cretaceous and tertiary periods were defined by geologists in the early 1800s. those of us who have developed and used dating techniques to solve scientific problems are well aware that the systems are not perfect; we ourselves have provided numerous examples of instances in which the techniques fail. after one hour, all the sand has fallen into the bottom bowl. two extensive studies done more than 25 years ago involved analyzing the isotopic composition of argon in such flows to determine if the source of the argon was atmospheric, as must be assumed in k-ar dating (dalrymple 1969, 26 flows; krummenacher 1970, 19 flows).'ve got two decay products, lead and helium, and they're giving two different ages for the zircon. they have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks., most of which are fragments of asteroids, are very interesting objects to study because they provide important evidence about the age, composition, and history of the early solar system. carbon on earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13. this is a tall order and the creationists have made no progress so far. the largest difference between these mineral pairs, in the ash from the gregory member, is less than 1%. once you understand the basic science, however, you can see how wrong assumptions lead to incorrect dates. and yet the results are the same within analytical error. isotope is what scientists call two or more forms of the same element.

Radiometric Dating: Back to Basics | Answers in Genesis

creationists seem to think that a few examples of incorrect radiometric ages invalidate all of the results of radiometric dating, but such a conclusion is illogical. the z-coal, the ferris coal, and the nevis coal in montana and saskatchewan all occur immediately above the k-t boundary. an hourglass, grains of fine sand fall at a steady rate from the top bowl to the bottom. discovery of fresh blood in a spectacular mosquito fossil strongly contradicts its own "scientific" age assignment of 46 million years. to understand how geologists “read” the age of a rock from these chemical analyses, let’s use the analogy of an hourglass “clock” (figure 2). ash beds from each of these coals have been dated by 40ar/39ar, k-ar, rb-sr, and u-pb methods in several laboratories in the us and canada. try, for example, wearing a watch that is not waterproof while swimming. presence of measurable radiocarbon in fossil wood supposedly tens and hundreds of millions of years old has been well-documented. the large majority of historic lava flows that have been studied either give correct ages, as expected, or have quantities of excess radiogenic 40ar that would be insignificant in all but the youngest rocks. don’t miss this special issue, which will give you the tools to tackle questions about evil and its true origin. other dating techniques, like k-ar (potassium-argon and its more recent variant 40ar/39ar), rb-sr (rubidium-strontium), sm-nd (samarium-neodynium), lu-hf (lutetium-hafnium), and u-pb (uranium-lead and its variant pb-pb), have all stood the test of time. people think that radioactive dating has proven the earth is billions of years old. plot shows the level of carbon-14 in the atmosphere as measured in new zealand (red) and austria (green), representing the northern and southern hemispheres, respectively. the impact also created shocked quartz crystals that were blasted into the air and subsequently fell to the west into the inland sea that occupied much of central north america at that time. sun alters radioactive decay rates many scientists rely on the assumption that radioactive elements decay at constant, undisturbed rates and therefore can be used as reliable clocks to measure the ages of rocks and artifacts. follow the links in this post to learn more about radiocarbon dating. to understand radiocarbon dating, you first have to understand the word isotope.

Radiometric Dating Does Work! | NCSE

of the most exciting and important scientific findings in decades was the 1980 discovery that a large asteroid, about 10 kilometers diameter, struck the earth at the end of the cretaceous period. scientists who use radiometric dating typically use every means at their disposal to check, recheck, and verify their results, and the more important the results the more they are apt to be checked and rechecked by others. when gas exchange is stopped, be it in a particular part of the body like in deposits on bones and teeth, or when the entire organism dies, the ratio of carbon-14 to carbon-12 begins to decrease., for example, every carbon atom contains six protons and six electrons, but the number of neutrons in each nucleus can be six, seven, or even eight. furthermore, the dating was done in 6 different laboratories and the materials were collected from 5 different locations in the western hemisphere. k-t boundary is recorded in numerous sedimentary beds around the world. evidence for rapid formation and failure of pleistocene “lava dams” of the western grand canyon, arizona. specially equipped laboratories can do this with accuracy and precision. these methods provide valuable and valid age data in most instances, although there is a small percentage of cases in which even these generally reliable methods yield incorrect results. the pierre shale, which is divided into identifiable sedimentary beds called members, also contains abundant fossils of numerous species of ammonites, ancestors of the chambered nautilus. the pierre shale also contains volcanic ash that was erupted from volcanoes and then fell into the sea, where it was preserved as thin beds. 40ar/39ar dating into the historical realm: calibration against pliny the younger. incremental heating experiments on 12 samples of sanidine yielded 46 data points that resulted in an isochron age of 1925 94 years. scientists measure the ratio of carbon isotopes to be able to estimate how far back in time a biological sample was active or alive. the heat of the impact melted some of the feldspar crystals in the granitic rocks of the impact zone, thereby resetting their internal radiometric clocks. how could all of this be so if the 40ar/39ar dating technique did not work? many people, radiometric dating might be the one scientific technique that most blatantly seems to challenge the bible’s record of recent creation.

What is radiometric dating and how is it used-How do geologists date rocks? Radiometric dating!

What is radiocarbon dating? | Earth | EarthSky

, it isn’t really a decay process in the normal sense of the word, like the decay of fruit. examples are granites (formed by cooling under the ground) and basalts (formed by cooling of lava at the earth’s surface). some are from primitive asteroids whose material is little modified since they formed from the early solar nebula., new observations have found that those nuclear decay rates actually fluctuate based on solar activity. measuring the age of this impact event independently of the stratigraphic evidence is an obvious test for radiometric methods, and a number of scientists in laboratories around the world set to work. these melted crystals, and therefore the impact, have been dated by the 40ar/39ar method at 74. because of their importance, meteorites have been extensively dated radiometrically; the vast majority appear to be 4. dating is often used to “prove” rocks are millions of years old.-argon and argon-argon dating of crustal rocks and the problem of excess argon. i could have selected many more examples but then this would have turned into a book rather than the intended short paper."excess argon": the "archilles' heel" of potassium-argon and argon-argon "dating" of volcanic rocks."and god called the light day, and the darkness he called night. because it’s unstable, carbon-14 will eventually decay back to carbon-12 isotopes. so if he knows the rate at which the parent decays, he can calculate how long it took for the daughter (measured in the rock today) to form. note that the carbon-14 (or radiocarbon) method is not used to date rocks because most rocks do not contain carbon. the most primitive type of meteorites are called chondrites, because they contain little spheres of olivine crystals known as chondrules. while the number of neutrons varies, every atom of any element always has the same number of protons and electrons.

Radiometric Dating

since such isotopes are thought to decay at consistent rates over time, the assumption is that simple measurements can lead to reliable ages. what dating method did scientists use, and did it really generate reliable results? today this shocked quartz is found in south dakota, colorado, and nebraska in a thin layer (the crow creek member) within a thick rock formation known as the pierre shale. thus geologists refer to uranium-lead (two versions), potassium-argon, rubidium-strontium, or samarium-neodymium dates for rocks. 79 ce mt vesuvius flow, the dating of which is described above, also contained excess 40ar. similar tektites were also found in mexico, and the berkeley lab found that they were the same age as the haiti tektites. in most instances, these efforts are flawed because the authors have misunderstood or misrepresented the data they attempt to analyze (for example, woodmorappe 1979; morris hm 1985; morris jd 1994). please follow the instructions we emailed you in order to finish subscribing. some meteorites, because of their mineralogy, can be dated by more than one radiometric dating technique, which provides scientists with a powerful check of the validity of the results. radiocarbon dating relies on the carbon isotopes carbon-14 and carbon-12. they must find rocks that have the isotopes listed above, even if these isotopes are present only in minute amounts. 40ar/39ar age of the manson impact structure, iowa, and correlative impact ejecta in the crow creek member of the pierra shale (upper cretaceous), south dakota and nebraska. second, ages were measured on two very different minerals, sanidine and biotite, from several of the ash beds. the results from all of the laboratories were remarkably consistent with the measured ages ranging only from 64. isotopes are radioactive; that is, they are unstable because their nuclei are too large. next step is to measure the amount of the parent and daughter isotopes in a sample of the rock unit. results of the manson impact/pierre shale dating study (izett and others 1998) are shown in figure 1.

Radiometric dating - Simple English Wikipedia, the free encyclopedia

ma would be insignificant in a 20 ma flow with equivalent potassium content. this short paper i have briefly described 4 examples of radiometric dating studies where there is both internal and independent evidence that the results have yielded valid ages for significant geologic events. confront creationists, proceedings of the 63rd annual meeting, pacific division, american association for the advancement of science, vol 1, part 3. only rarely does a creationist actually find an incorrect radiometric result (austin 1996; rugg and austin 1998) that has not already been revealed and discussed in the scientific literature., many dating methods that don't involve radioisotopes—such as helium diffusion, erosion, magnetic field decay, and original tissue fossils—conflict with radioisotope ages by showing much younger apparent ages. new discoveries of rate fluctuations continue to challenge the reliability of radioisotope decay rates in general—and thus, the reliability of vast ages seemingly derived from radioisotope dating. others are from larger asteroids that got hot enough to melt and send lava flows to the surface. some so-called creation scientists have attempted to show that radiometric dating does not work on theoretical grounds (for example, arndts and overn 1981; gill 1996) but such attempts invariably have fatal flaws (see dalrymple 1984; york and dalrymple 2000)., it is an approach doomed to failure at the outset. in the case of st severin, for example, we have 4 different natural clocks (actually 5, for the pb-pb method involves 2 different radioactive uranium isotopes), each running at a different rate and each using elements that respond to chemical and physical conditions in much different ways. it is these studies, and the many more like them documented in the scientific literature, that the creationists need to address before they can discredit radiometric dating. most often, this is a rock body, or unit, that has formed from the cooling of molten rock material (called magma). among the significant events that caused a temporary but significant spike in the atmospheric carbon-14 to carbon-12 ratio were above-ground nuclear test detonations in the two decades following world war ii. we often test them under controlled conditions to learn when and why they fail so we will not use them incorrectly. we now know that the impact site is located on the yucatan peninsula. since both the ash beds and the tektites occur either at or very near the k-t boundary, as determined by diagnostic fossils, the tektites and the ash beds should be very nearly the same age, and they are (table 2). if you could peer at the atoms of two different isotopes, you’d find equal numbers of protons but different numbers of neutrons in the atoms’ nucleus or core.

Radiometric Dating | The Institute for Creation Research

Radioactive dating - Australian Museum

the cretaceous period, a large meteorite struck the earth at a location near the present town of manson, iowa. the second thing is that some of the results have been repeated using the same technique, which is another check against analytical errors. line: radiocarbon dating is a technique used by scientists to learn the ages of biological specimens – for example, wooden archaeological artifacts or ancient human remains – from the distant past. decay rates not stablefor about a century, radioactive decay rates have been heralded as steady and stable processes that can be reliably used to help measure how old rocks are. dating of grand canyon rocks: another devastating failure for long-age geology. detailed description of radiocarbon dating is available at the wikipedia radiocarbon dating web page. few verified examples of incorrect radiometric ages are simply insufficient to prove that radiometric dating is invalid. autoplay is enabled, a suggested video will automatically play next. after all, textbooks, media, and museums glibly present ages of millions of years as fact. actionaction alerts & ongoing campaignshow to and trainingask ncse for helpscience booster clubssign up for action alertsteachsign up for ncseteachscientist in the classroomdealing with denialclassroom resourceslearnlibraryevolutionclimate changesurveys & pollslegislation & court casesanti-science education legislationcourt casesclassroom resourcesaboutwhat we doncse newsletterboard of directorsadvisory councilsupporting organizationsstaffneed a speaker? process of changing one element (designated as the parent isotope) into another element (referred to as the daughter isotope) is called radioactive decay. few people know how radiometric dating works or bother to ask what assumptions drive the conclusions. as a result, this method is not used except in rare and highly specialized applications. so, after only half an hour, half the sand should be in the top bowl, and the other half should be in the bottom bowl. you for signing up to receive email newsletters from answers in genesis. ma), is in very good agreement with the ages of the ash beds above and below it. a geologist tests a rock sample, he assumes all the daughter atoms were produced by the decay of the parent since the rock formed.

How Does Radiocarbon Dating Work? - Instant Egghead #28

Evolution: Library: Radiometric Dating

as a result, it is nearly impossible to be completely fooled by a good set of radiometric age data collected as part of a well-designed experiment. the falling sand represents radioactive decay, and the sand at the bottom represents the daughter isotope (lead-206, argon-40, etc). way of analogy, the sand grains in the top bowl represent atoms of the parent radioisotope (uranium-238, potassium-40, etc. (these are the moving particles measured by geiger counters and the like. proceedings of the fourth international conference on creationismpittsburgh: creation science fellowship, 1998. chemical element, such as carbon and oxygen, consists of atoms. for this reason, icr research has long focused on the science behind these dating techniques. for example, after extensive testing over many years, it was concluded that uranium-helium dating is highly unreliable because the small helium atom diffuses easily out of minerals over geologic time. the third is that all three meteorites were dated by more than one method — two methods each for allende and guarena, and four methods for st severin. it is, therefore, not surprising that many misconceptions about what radiocarbon can or cannot do and what it has or has not shown are prevalent among creationists and evolutionists - lay people as well as scientists not directly involved in this field. ma (million years; izett and others 1998), but that is not the whole story by a long shot. creationists who wants to dispute the conclusion that primitive meteorites, and therefore the solar system, are about 4. such failures may be due to laboratory errors (mistakes happen), unrecognized geologic factors (nature sometimes fools us), or misapplication of the techniques (no one is perfect). god’s curse is a historical reality, and we can see its results in everyday life. the fossils, when combined with geologic mapping, allow the various exposed sections of the pierre shale to be pieced together in their proper relative positions to form a complete composite section (figure 1). many more, plus a discussion of the different types of meteorites and their origins, can be found in dalrymple (1991). most estimates of the age of the earth are founded on this assumption.

Radiometric Dating

earthsky team has a blast bringing you daily updates on your cosmos and world. it can be used on objects as old as about 62,000 years. to achieve stability, the atom must make adjustments, particularly in its nucleus. and the evening and the morning were the first day. it can be used on objects as old as about 62,000 years. the 40ar/39ar technique, which is now used instead of k-ar methods for most studies, has the capability of automatically detecting, and in many instances correcting for, the presence of excess 40ar, should it be present. atoms of the same element that have different numbers of neutrons are called isotopes. the early afternoon of august 24, 79 ce, mt vesuvius erupted violently, sending hot ash flows speeding down its flanks. this is extremely powerful verification of the validity of both the theory and practice of radiometric dating. numerous thin beds of volcanic ash occur within these coals just centimeters above the k-t boundary, and some of these ash beds contain minerals that can be dated radiometrically. even if against all odds they should succeed, it still would not prove that the earth is young. tektites are easily recognizable and form in no other way, so the discovery of a sedimentary bed (the beloc formation) in haiti that contained tektites and that, from fossil evidence, coincided with the k-t boundary provided an obvious candidate for dating. it’s not absolutely constant due to several variables that affect the levels of cosmic rays reaching the atmosphere, such as the fluctuating strength of the earth’s magnetic field, solar cycles that influence the amount of cosmic rays entering the solar system, climatic changes, and human activities. with scores of other bible-believing geologists, icr scientists have made key observations that compel us to reject the millions-of-years apparent ages that these techniques yield:First, rocks of known age always show vastly inflated radioisotope “ages. scientists are looking for the ratio of those two isotopes in a sample. field of radiocarbon dating has become a technical one far removed from the naive simplicity which characterized its initial introduction by libby in the late 1940's. so let’s take a closer look and see how reliable this dating method really is.

Radiometric dating | chronology |

regularly use five parent isotopes to date rocks: uranium-238, uranium-235, potassium-40, rubidium-87, and samarium-147. the collision threw many tons of debris into the atmosphere and possibly led to the extinction of the dinosaurs and many other life forms. radiocarbon dating today is done using an accelerator mass spectrometer, an instrument that directly counts the numbers of carbon 14 and carbon12 in a sample. of the handful of flows that did contain excess 40ar, only a few did so in significant amounts. in the cosmic story of carbon-14 ethan siegel writes:The only major fluctuation [in carbon-14] we know of occurred when we began detonating nuclear weapons in the open air, back in the mid-20th century. this isotope lets scientists learn the ages of once-living things. is rare for a study involving radiometric dating to contain a single determination of age.) the end result is a stable atom, but of a different chemical element (not carbon) because the atom now has a different number of protons and electrons. 14 dating 1 | life on earth and in the universe | cosmology & astronomy | khan academy. these flows buried and destroyed pompeii and other nearby roman cities. he walks into the room when half the sand is in the top bowl, and half the sand is in the bottom bowl. therefore, carbon has three isotopes (variations), which are specified carbon-12, carbon-13, and carbon-14 (figure 1). its exact location in the stratigraphic column at any locality has nothing to do with radiometric dating — it is located by careful study of the fossils and the rocks that contain them, and nothing more. is not the only dating study to be done on an historic lava flow. future articles will explore the assumptions that can lead to incorrect dates and how the bible’s history helps us make better sense of the patterns of radioactive “dates” we find in the rocks today.'t radioisotope dating prove rocks are millions of years old? radiocarbon dating is a term for radiocarbon dating based on timestamps left by above-ground nuclear explosions, and it is especially useful for putting an absolute age on organisms that lived through those events.

Radiometric Dating

in some cases, the isotopes eject particles, primarily neutrons and protons. there’s a difference in the relative atomic masses of two isotopes. dating is based on an observable fact of science: unstable atoms will break down over a measurable period of time. see the articles below for more information on the pitfalls of these dating methods. rays bombard earth’s atmosphere, creating the unstable isotope carbon-14. a carbon atom is a carbon atom is a carbon atom …. in order to accomplish their goal of discrediting radiometric dating, however, creationists are faced with the daunting task of showing that a preponderance of radiometric ages are wrong — that the methods are untrustworthy most of the time. because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in earth’s atmosphere. even things that work well do not work well all of the time and under all circumstances. these parent radioisotopes change into daughter lead-206, lead-207, argon-40, strontium-87, and neodymium-143 isotopes, respectively. thus any potential error due to excess 40ar was eliminated by the use of this technique, which was not available when the studies by dalrymple (1969) and krummenacher (1970) were done. in the following article, some of the most common misunderstandings regarding radiocarbon dating are addressed, and corrective, up-to-date scientific creationist thought is provided where appropriate. informationdonate/joinbecome a memberbe a sustainerfree grad student membershipmore ways to giveprivacy policy and disclaimerdisclosures required by state law. both studies detected, in a few of the flows, deviations from atmospheric isotopic composition, most often in the form of excess 40ar. creationist approach of focusing on examples where radiometric dating yields incorrect results is a curious one for two reasons. only when young-earth creationists produce convincing quantitative, scientific evidence that the earth is young will they be worth listening to on this important scientific matter. all they indicate is that the methods are not infallible.

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