Scientific Dating Methods

[scameter18]

Anytime one studies a field of science that involves historical things, whether biological, cosmological, etc., they always give an age - “this fossil is at least 3.5 billion years old”. I have done a little research on the dating methods they commonly use, which are primarily Carbon 14, geological strata analysis, and a few others which are much less precise. Carbon 14’s range of accuracy is roughly 200,000 years, and from 100,000 back it is much less accurate. From 200k back, it is very unreliable. Geological strata is a bit more accurate, but because it is difficult for scientists to truly know how geology functioned so long ago, they can only guess by current standards how those strata formed and how old they really are. They can only really give a sequential order of appearance for various natural things; offering a specific age is very precarious using geological strata analysis.

Yet with this uncertainty, they continue to give very precise and incredibly ancient dating for things. I would like to avoid discussing evolution here, since it has been temporarily banned in this forum. I just want to know how scientists are able to conclude these incredibly ancient ages with such precision, when their most common dating methods only go back so far, and others are unreliable at best. If anyone has any info, it’d be appreciated.

 

[rossum]

I have done a little research on the dating methods they commonly use, which are primarily Carbon 14, geological strata analysis, and a few others which are much less precise.

Your (creationist?) source is misinforming you. C-14 dating is just one form of radiometric dating. There are many other forms of Radiometric dating besides C-14. Your source also leaves out tree rings, thermoluminescence, varves, ice layers, electron spin resonance and others.

Carbon 14’s range of accuracy is roughly 200,000 years, and from 100,000 back it is much less accurate. From 200k back, it is very unreliable.

Your source is misinforming you. Carbon dating is usually good to about 30,000 to 50,000 years old. With very good equipment and a completely uncontaminated sample it might be able to reach 75,000 years. Other radiometric methods are used for older dates: U-Pb, Rb-Sr, Ar-Ar etc. Some of them can reach back billions of years. It is those methods that we use to tell us that the Earth is about 4.5 billion years old.

Geological strata is a bit more accurate, but because it is difficult for scientists to truly know how geology functioned so long ago, they can only guess by current standards how those strata formed and how old they really are. They can only really give a sequential order of appearance for various natural things; offering a specific age is very precarious using geological strata analysis.

Which is why we use radiometric dating as well. If we can date one stratum at 5 million years and another stratum at 5.5 billion years then the rocks between them will be between those two dates unless otherwise disturbed.

Yet with this uncertainty, they continue to give very precise and incredibly ancient dating for things.

The uncertainty is an artefact of the misinformed sources you have been studying. When a scientist gives a date she will also give the level of uncertainty about that date. You can see how accurate the measurement is by the width of the error bars on the figure given. It is unfortunate that sometimes the press reports knock off the error bars so we do not always see them unless we delve into the scientific literature. For example, a Rb-Sr isochron date for the Amitsoq Gneiss is 3.70 ± 0.14 billion years. That means that there is an error of 140 million years either way on that date. The Gneiss is between 3.84 and 3.56 billion years old.

I would like to avoid discussing evolution here, since it has been temporarily banned in this forum. I just want to know how scientists are able to conclude these incredibly ancient ages with such precision, when their most common dating methods only go back so far, and others are unreliable at best. If anyone has any info, it’d be appreciated.

Three web sources I would suggest:* Weins - Radiometric Dating - A Christian Perspective.

• Dalrymple - How Old is the Earth.
• Stassen - The Age of the Earth.

Wherever you were getting your information from I suggest that you stop using that source. It is misinforming you.

rossum

 

[Edmundus1581]

Thanks Rossum for a comprehensive scientific response to this.

I would just like to add a note on the difference between scientific reporting, and popular reporting. If one reads in a newspaper article “this fossil is at least 3.5 billion years old” it does not mean that the scientists have said it is 3.5 billion years old, and not 3.0 billion, or 4.0 billion. The original scientific article will have including the method, or several methods, or measurement, and any uncertainty. The article will have been peer reviewed before publication, with the best assurance that the conclusions to not overstate the evidence. The newspaper will have ommitted all this extra information for the sake of brevity and readability. If you have doubts about the validity of the science, then you must read the original publication, not the newspaper report.

 

[scameter18]

Thanks for the information. I would suggest someone edit Wikipedia, which is the primary source of my information.

 

[edwest2]

Your (creationist?) source is misinforming you. C-14 dating is just one form of radiometric dating. There are many other forms of Radiometric dating besides C-14. Your source also leaves out tree rings, thermoluminescence, varves, ice layers, electron spin resonance and others.

Your source is misinforming you. Carbon dating is usually good to about 30,000 to 50,000 years old. With very good equipment and a completely uncontaminated sample it might be able to reach 75,000 years. Other radiometric methods are used for older dates: U-Pb, Rb-Sr, Ar-Ar etc. Some of them can reach back billions of years. It is those methods that we use to tell us that the Earth is about 4.5 billion years old.

Which is why we use radiometric dating as well. If we can date one stratum at 5 million years and another stratum at 5.5 billion years then the rocks between them will be between those two dates unless otherwise disturbed.

The uncertainty is an artefact of the misinformed sources you have been studying. When a scientist gives a date she will also give the level of uncertainty about that date. You can see how accurate the measurement is by the width of the error bars on the figure given. It is unfortunate that sometimes the press reports knock off the error bars so we do not always see them unless we delve into the scientific literature. For example, a Rb-Sr isochron date for the Amitsoq Gneiss is 3.70 ± 0.14 billion years. That means that there is an error of 140 million years either way on that date. The Gneiss is between 3.84 and 3.56 billion years old.

Three web sources I would suggest:* Weins - Radiometric Dating - A Christian Perspective.

• Dalrymple - How Old is the Earth.
• Stassen - The Age of the Earth.

Wherever you were getting your information from I suggest that you stop using that source. It is misinforming you.

rossum

I don’t understand the insistence. Too often, some are misled simply because a poster says as much. I have seen two very good examples recently where I knew the information was false but it just got repeated.

Peace,
Ed

 

[edwest2]

Some food for thought:

"Andrew Snelling has suggested that fractionation (sorting) of elements in the molten state in the Earth’s mantle could be a significant factor in explaining the ratios of isotope concentrations which are interpreted as ages.

“As long ago as 1966, Nobel Prize nominee Melvin Cook, professor of metallurgy at the University of Utah, pointed out evidence that lead isotope ratios, for example, may involve alteration by important factors other than radioactive decay.[39] Cook noted that, in ores from the Katanga mine, for example, there was an abundance of lead-208, a stable isotope, but no Thorium-232 as a source for lead-208. Thorium has a long half-life (decays very slowly) and is not easily moved out of the rock, so if the lead-208 came from thorium decay, some thorium should still be there. The concentrations of lead-206, lead-207, and lead-208 suggest that the lead-208 came about by neutron capture conversion of lead-206 to lead-207 to lead-208. When the isotope concentrations are adjusted for such conversions, the ages calculated are reduced from some 600 Ma to recent. Other ore bodies seemed to show similar evidence. Cook recognized that the current understanding of nuclear physics did not seem to allow for such a conversion under normal conditions, but he presents evidence that such did happen, and even suggests how it could happen.”

Peace,
Ed

 

[Sonoran_Son]

Thanks, Rossum, for that quick rundown.

Some food for thought:

"Andrew Snelling has suggested that fractionation (sorting) of elements in the molten state in the Earth’s mantle could be a significant factor in explaining the ratios of isotope concentrations which are interpreted as ages.

“As long ago as 1966, Nobel Prize nominee Melvin Cook, professor of metallurgy at the University of Utah, pointed out evidence that lead isotope ratios, for example, may involve alteration by important factors other than radioactive decay.[39] Cook noted that, in ores from the Katanga mine, for example, there was an abundance of lead-208, a stable isotope, but no Thorium-232 as a source for lead-208. Thorium has a long half-life (decays very slowly) and is not easily moved out of the rock, so if the lead-208 came from thorium decay, some thorium should still be there. The concentrations of lead-206, lead-207, and lead-208 suggest that the lead-208 came about by neutron capture conversion of lead-206 to lead-207 to lead-208. When the isotope concentrations are adjusted for such conversions, the ages calculated are reduced from some 600 Ma to recent. Other ore bodies seemed to show similar evidence. Cook recognized that the current understanding of nuclear physics did not seem to allow for such a conversion under normal conditions, but he presents evidence that such did happen, and even suggests how it could happen.”

Peace,
Ed

What is/are the source(s) of your quotes?

 

[edwest2]

Here is my source:

christiananswers.net/q-aig/aig-c007.html

Peace,
Ed

 

[Sonoran_Son]

Here is my source:

christiananswers.net/q-aig/aig-c007.html

Peace,
Ed

Thanks.

Here is another source that will be relevant to anyone interested in the AIG article:

talkorigins.org/indexcc/CD/CD016.html

 

[The_Exodus]

Your source also leaves out tree rings, thermoluminescence, varves, ice layers, electron spin resonance and others.

None of which exist, nor change, nor age, in your philosophy.

rossum:

Your source is misinforming you.

Misinformation, on your view, is impossible – or, rather, is the only thing possible – since we cannot grasp reality, and there is no ultimate truth. Hence, every point in your post is as erroneous about the world as you claim his to be.

It’s weird how so many people forget their philosophy the moment they want to make a point.

rossum:

Carbon dating is usually good to about 30,000 to 50,000 years old.

Has this been shown empirically? Isn’t it rather the case that it rests on many assumptions – such as uniform and predictible decay – which have no wise been observed over such periods?

 

[rossum]

None of which exist, nor change, nor age, in your philosophy.

You appear to have misunderstood Madhyamika Buddhist philosophy. Those things exist, change and age in the same way as everything else in the world exists, changes and ages.

Has this been shown empirically? Isn’t it rather the case that it rests on many assumptions – such as uniform and predictible decay – which have no wise been observed over such periods?

It has been shown empirically. There is no assumption of uniform and predictable decay, it has been measured to be uniform and predictable. How can we tell what it was in the past? Simple. We measure the decay rates in distant astronomical objects. All measurements of radioactive decay rates in distant astronomical objects are the same as the rates measured today on Earth. There is no assumption made. A supernova 200,000 light years away tells us what the decay rates were 200,000 years ago.

What is not uniform is the rate of creation of radioactive carbon in the atmosphere. That has been measured by correlating Carbon-14 dates with independent dates derived from other methods such as counting tree rings, counting varves, counting annual layers of coral and counting ice layers. Correlating dates from the different independent sources allows us to get a reasonably accurate figure for C-14 dates. For an example see Atmospheric Radiocarbon Calibration Beyond 11,900 Cal Bp From Lake Suigetsu Laminated Sediments. Figures 1 and 2 in that reference shows the sort of calibration that is used to convert C-14 dates into actual dates.

rossum

 

[edwest2]

The problem is how do we measure distance in space? There are non-distance related redshifts out there. Even Hubble said that redshift might not measure distance.

ldolphin.org/univ-age.html

Peace,
Ed

 

[rossum]

The problem is how do we measure distance in space? There are non-distance related redshifts out there. Even Hubble said that redshift might not measure distance.

ldolphin.org/univ-age.html

Redshifts are not the only way to measure astronomical distances. Like many things in science, including ages, distances are measured by as many independent methods as possible and the results correlated. See Cosmic Distance Ladder for an overview of the different methods used and the links between them.

Here is a diagram from that article:

http://upload.wikimedia.org/wikipedia/en/1/13/Extragalactic_distance_ladder.JPG

See the Wikipedia article for a fuller explanation.

rossum