probably have older trees, but as you have said carbon is to determine the date for relatively closer ages, like 0-10 000, for older fossils there is other methods, an example for method to find the date of million years old bone is the method of proportion of fluorine and phosphate or other elements isotopes ;)
Just so you know.. the way they get the 10K data for tree rings is by overlapping the rings in living trees to the rings in dead ones. Because the trees exhibit growth rings that are specific to the variability in growing seasons, you can use this variability to find, say, the pattern in the last hundred years of a tree's life and match it to the first 100 years of a younger tree's life.
Bristle-cone pines have been dated at 9,000 years or more using living and dead cores. I guess the oldest living supposedly is only 4,000 plus years. Yet I recall that some yahoo cut down a living specimen and realized he'd cut down a tree that was older than that. I seem to recall near to 9000. Now the area is, according to the documentary I saw, supposedly protected from such idiots. There could be a 10,000 year old tree out there.
@MonsterSlayer14 The idea is that you can check the assumption that the Carbon-14 levels have been constant in the atmosphere. In a nutshell, it is known that the levels of Carbon 14 have had major fluctuations. You cannot use C14 dating on anything after the Industrial Revolution, because of the increase in normal carbon in the atmosphere (which would make things that died after the industrial revolution look older).
I am actually putting together a lot of Carbon Dating info on my web site.
So the burning of fossil fuels screws up the amount of carbon 14 in the atmosphere, then what about the artifacts and stuff in the last 50 years that scientists have dated and would that mess the method up so that you can't have accurate dates?
@TheFrugalGamer You're right man, you completely missed it. You use tree rings. Though he didn't address this particular point in too much detail. Just look it up.
@99pinkrose It represents the amount of growing that a tree does in a given year. During the spring and summer it grows quickly, while during the late autumn the tree grows slowly.
The visible portion of the 13-foot-tall (4-meter-tall) "Christmas tree" isn't ancient, but its root system has been growing for 9,550 years, according to a team led by Leif Kullman, professor at Umeå University's department of ecology and environmental science in Sweden.
Do they have a calibration method for really old stuff, or do they use different techniques? Comparing fossils from different continents and then use observations from tectonic movement or something?
Also, just realized that when you're talking about 200 million years an error margin of 1 million years is equally accurate as an error margin of 100 years on 20.000. That's pretty weird. :)
@noxure Really old rocks are dated using other types of radioactive isotopes. For example, potassium-argon (or K-Ar); K40 radioactively decays into Ar40. Argon is a noble gas, so if a rock fully melts, it will escape. When the rock hardens again, it has no argon and the only source is potassium decaying into it. If we examine the rock later and find it has equal amounts of K40 and Ar40, we know the rock has been hard for one half-life (~1.25 billion years).
@noxure That's how K-Ar dating works, but there are other ways. In uranium-lead, some rocks, like zircon, repel lead when forming, so even if there's lead in the magma it won't be in the zircon minerals when they first form. Then there's isochron dating (I think one of the most clever tricks in science), where scientists use a group of minerals that all formed from the same pool of magma to determine the original amount of daughter product in each rock.
Like cmx said, there's a process in dendrochronology that let's you link dead trees. You see, weather effects tree growth, and not only does this show winter and summer, it also shows the difference between individual summers and individual winters. A long period of good weather will leave bigger summer growth rings in all the trees in a region, young and old, so you can match them up at that time period, and then, even if the old tree dies, you can still tell it's age from the young tree.
You don't need 10,000 year old trees for calibration, since tree rings can be linked over different trees in the same regions (in other words, you can find older trees whose ring patterns overlap with younger trees).
en.wikipedia.*rg/wiki/List_of_oldest_trees
(*=o)
Prometheus 4,862 years (verified)
probably have older trees, but as you have said carbon is to determine the date for relatively closer ages, like 0-10 000, for older fossils there is other methods, an example for method to find the date of million years old bone is the method of proportion of fluorine and phosphate or other elements isotopes ;)
nekojx 1 month ago
Just so you know.. the way they get the 10K data for tree rings is by overlapping the rings in living trees to the rings in dead ones. Because the trees exhibit growth rings that are specific to the variability in growing seasons, you can use this variability to find, say, the pattern in the last hundred years of a tree's life and match it to the first 100 years of a younger tree's life.
PaleHearse 1 month ago
sonic dot net slash bristlecone slash dendro dot html
Link to the pine story.
rogerscottq 1 month ago in playlist More videos from khanacademy
Bristle-cone pines have been dated at 9,000 years or more using living and dead cores. I guess the oldest living supposedly is only 4,000 plus years. Yet I recall that some yahoo cut down a living specimen and realized he'd cut down a tree that was older than that. I seem to recall near to 9000. Now the area is, according to the documentary I saw, supposedly protected from such idiots. There could be a 10,000 year old tree out there.
rogerscottq 1 month ago in playlist More videos from khanacademy
so you take a sample off the tree ring specified for that year and from that sample you can measure what the c14 lvl was??
MonsterSlayer14 4 months ago in playlist More videos from khanacademy
@MonsterSlayer14 The idea is that you can check the assumption that the Carbon-14 levels have been constant in the atmosphere. In a nutshell, it is known that the levels of Carbon 14 have had major fluctuations. You cannot use C14 dating on anything after the Industrial Revolution, because of the increase in normal carbon in the atmosphere (which would make things that died after the industrial revolution look older).
I am actually putting together a lot of Carbon Dating info on my web site.
GreenSlugg 3 months ago
So the burning of fossil fuels screws up the amount of carbon 14 in the atmosphere, then what about the artifacts and stuff in the last 50 years that scientists have dated and would that mess the method up so that you can't have accurate dates?
AngelKnight85268 4 months ago
I know I'm an idiot and I probably completely missed this but how do we know that the half life of Carbon 14 is 5730 years?
TheFrugalGamer 5 months ago
@TheFrugalGamer You're right man, you completely missed it. You use tree rings. Though he didn't address this particular point in too much detail. Just look it up.
Maracachucho 4 months ago
@Maracachucho Yeah I read about it in more detail after watching this and have a much better understanding. Thanks for the help.
TheFrugalGamer 4 months ago
@TheFrugalGamer He was just using that number as an example.
hamoan66boi 3 months ago
thanks
paulceltics 9 months ago
What is reason behind distinct line in tree barks suggestive of 1 year??
99pinkrose 11 months ago
@99pinkrose It represents the amount of growing that a tree does in a given year. During the spring and summer it grows quickly, while during the late autumn the tree grows slowly.
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/.../
The visible portion of the 13-foot-tall (4-meter-tall) "Christmas tree" isn't ancient, but its root system has been growing for 9,550 years, according to a team led by Leif Kullman, professor at Umeå University's department of ecology and environmental science in Sweden.
/.../
From National Geographic.
10k years is possible for a tree.
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CokeWTF 1 year ago
I love your videos. You are a great teacher. Keep up the good work. :)
cyberprodigy 1 year ago
Excellent video, Sal. Here's a video that explains what some of the fellas below are talking about: v=aLFKM886l4Q
Another point regarding other radiometric dating:
v=iGDrq8rikJc
You may also want to google "reservoir effect."
TheFallibleFiend 1 year ago
Do they have a calibration method for really old stuff, or do they use different techniques? Comparing fossils from different continents and then use observations from tectonic movement or something?
Also, just realized that when you're talking about 200 million years an error margin of 1 million years is equally accurate as an error margin of 100 years on 20.000. That's pretty weird. :)
noxure 1 year ago
@noxure Carbon dating is not really used on true fossils as they lack carbon, so yeah different materials are used.
AcanLord 1 year ago
@noxure Really old rocks are dated using other types of radioactive isotopes. For example, potassium-argon (or K-Ar); K40 radioactively decays into Ar40. Argon is a noble gas, so if a rock fully melts, it will escape. When the rock hardens again, it has no argon and the only source is potassium decaying into it. If we examine the rock later and find it has equal amounts of K40 and Ar40, we know the rock has been hard for one half-life (~1.25 billion years).
Hooya2 1 year ago
@Hooya2 I see. So basically you need an isotope that decays into a different element that can only be contained by the rock if it's solid.
noxure 1 year ago
@noxure That's how K-Ar dating works, but there are other ways. In uranium-lead, some rocks, like zircon, repel lead when forming, so even if there's lead in the magma it won't be in the zircon minerals when they first form. Then there's isochron dating (I think one of the most clever tricks in science), where scientists use a group of minerals that all formed from the same pool of magma to determine the original amount of daughter product in each rock.
Hooya2 1 year ago
Like cmx said, there's a process in dendrochronology that let's you link dead trees. You see, weather effects tree growth, and not only does this show winter and summer, it also shows the difference between individual summers and individual winters. A long period of good weather will leave bigger summer growth rings in all the trees in a region, young and old, so you can match them up at that time period, and then, even if the old tree dies, you can still tell it's age from the young tree.
Hooya2 1 year ago 2
You don't need 10,000 year old trees for calibration, since tree rings can be linked over different trees in the same regions (in other words, you can find older trees whose ring patterns overlap with younger trees).
cmxcmx 1 year ago 2
yayyy first comment! :)
wizwazzle29 1 year ago