[Q] Scientific Dating Methods

[brad8134]

Hello People. I am writing to ask about dating methods. Are all scientific dating methods accurate past a thousand years? For instance The New York Times Thursday, August 4, 1988 published an article of planes that had gone down in WW2 and were under 260 feet of Ice. I know that if 260 feet of ice took 45 years then there is know way we could get millions of years with Ice Core Dating especially since the the rings can be caused from heating and cooling of the earths surface during seasons.

[Turtle]

ice compacts over time.

... The gradually increasing weight of overlying layers compresses deeply buried snow into ice, but annual bands remain. Relatively young and shallow snow becomes packed into coarse and granular crystals called firn (top: 53 meters deep). Older and deeper snow is compacted further (middle: 1,836 meters). At the bottom of a core (lower: 3,050 meters), rocks, sand, and silt discolor the ice. (Photographs courtesy U.S. National Ice Core Laboratory. ...

Paleoclimatology: The Ice Core Record : Feature Articles

 

here's an article on the oldest cores reported as ~750,000 years old & recovered in Antarctica.

[CraigD]

Welcome to hypography, brad! :)

Are all scientific dating methods accurate past a thousand years?

There are many scientific dating methods' date=' each with relative strengths and weaknesses. Some are accurate over only very short periods, other over very long ones. Some apply only to special kinds of sample, others to many different kinds.

 

I’m guessing from this from another post of yours:

… Creationists and evolution alike. They have their ideas and they twist the facts to fit their conclusion. Wake world they are both theories. None has been proven and both take faith and i challenge someone to prove me wrong.

that you’re interested primarily in understanding the scientific dating methods used to determine that the Earth is much older than the five to ten thousand years religionists of the sort usually termed “young Earth creationist” arrive at via techniques such as counting time references in the Christian Bible, and less interested in methods used to determine much shorter periods, such as the age of a painting, pot, or cadaver. Those long time period dating methods can be grouped into 2 main categories:

• Stratographic methods, which measure how or how deeply the sample to be dated is buried by a sediment that accumulates at a known rate
  
• Radiometric methods, which measure the amount of a radioisotope in the sample
  

Stratographic methods fall into two basic sub-catagories:

• Incremental methods, where you can directly count individual year markers. Ice cores fall into this category. Although very precise, because ice in deep-ice formations accumulates quickly, and ice compresses less than most other sediments, for the same reason, ice cores aren’t able to date samples more than about 1 million years old
  
• Context methods, where you can’t actually count year markers, so must use less direct techniques. Most geological sampling, which can establish sample ages of many hundreds of millions of years, is of this kind. A great strength of these methods are that they can date anything that allows itself to be buried over time and leave some recognizable mark in the burying strata.
  

Radiometric dating is both precise and capable of very long time periods, because radioactive decay is very precise, and inverse exponential. IT only works on special kinds of samples that absorb a predictable amount of some radioisotope, then stop absorbing it, such as primordial rocks such as meteorites (which begin with supernova remnants with a high concentration or uranium and similar radioisotopes) and once-living plant and animal tissues, which absorb radioisotopes from the atmosphere due to life processes (transpiring, breathing, etc) that cease when the organism dies. Fortunately, many sedimentary formations contain such material, so radiometric dating can be used in combination with stratographic dating.

 

There are lots of good starting places for studying these and other dating methods, such as the wikipedia article “geochronology”

[brad8134]

Ok for the Ice Core method the story I mentioned earlier is as follows:

 

17 miles off the east coast of Greenland, that Bob Cardin members of his squadron had to ditch their six P-38’s and two B-17’s when they ran out of gas in 1942. In 1981, several members of this original squad decided to see if they could recover their aircraft. They flew back to the spot in Greenland where they went down. There was nothing there. After many years of searching they found the airplanes in 1988 three miles from their original location and under approximately 260 feet of ice! They went on to actually recovered one of them (“Glacier Girl” – a P38), which was eventually restored to her former glory.20

 

It took only 46 years to bury the planes in over 260 feet of ice and move them some 3 miles from their original location. That's around 17 feet of compact snow per year and about 100 meters of movement per year. In a telephone interview, Bob Cardin was asked how many layers of ice were above the recovered airplane. His response “Oh, there were many hundreds of layers of ice above the airplane.” When told that each layer was supposed to represent one year of time, Bob said, “That is impossible! Each of those layers is a different warm spell – warm, cold, warm, cold, warm, cold

 

About all dating methods don't the elements effect every single one of them. wouldn't all them work correctly only if undisturbed and from starting at point A and ending at point B (Potassium-argon dating or Uranium-thorium-lead dating).

Also, Stratographic methods, how would Mt StHelens fit into that there are trees that are completely buried, at different levels, at the bottom of Spirit lake (I believe that's the name of that lake). Another interesting thing about Mt StHelens I find hard to get around; there is a canyon that was dug out, from the water that got dammed up from the volcano. It ate a new path down the Mountain leaving a canyon an sixteen the size of the Grand Canyon and was carved overnight. But that is for another forum.

 

What would you say the best of the dating methods is? and does it still have its problems? if so what are they?

[Pyrotex]

Ok for the Ice Core method the story I mentioned earlier is as follows:... It took only 46 years to bury the planes in over 260 feet of ice and move them some 3 miles from their original location. That's around 17 feet of compact snow per year and about 100 meters of movement per year. In a telephone interview, Bob Cardin was asked how many layers of ice were above the recovered airplane. His response “Oh, there were many hundreds of layers of ice above the airplane.” When told that each layer was supposed to represent one year of time, Bob said, “That is impossible! Each of those layers is a different warm spell – warm, cold, warm, cold, warm, cold

Ice accumulation is not linear. The current year might deposit 25 feet of snow/ice. As previous layers get buried, the weight of the snow/ice above compresses them. After several thousand years, the bottom layers may be only one or two feet thick per year.

About all dating methods don't the elements effect every single one of them. wouldn't all them work correctly only if undisturbed and from starting at point A and ending at point B (Potassium-argon dating or Uranium-thorium-lead dating).

Not all methods are affected equally. Tree rings and ice layers still record clear annual records despite what elements be in them -- or what weather "elements" have occurred. These methods have been verified by comparing them with other methods, such as radiographic. In this manner, a stratigraphic method can be verified, or "calibrated" by a radiographic analysis of the same material.

 

Ice cores do reflect some warming/cooling cycles, but the overall annual cycle is totally clear, and no significant confusion arises. Are you assuming that scientists would NOT notice the possibility of errors, and work to find ways of avoiding or eliminating them? Of course they do this, so that their analyses will survive all criticisms from other scientists (and from folks like you).

...What would you say the best of the dating methods is? and does it still have its problems? if so what are they?

They are all good and useful. They serve to calibrate each other.

Tree rings can reach back maybe 1,000 years and are very accurate.

Ice rings can reach back (in some places) 700,000 years and are very accurate.

Radio carbon dating works best on plant material and goes back 20,000 years or so.

Uranium and thorium dating works in various kinds of mineral crystals and goes back many millions of years.

Rock strata is quite reliable back half a billion years, and somewhat reliable back to the origins of the Earth 4.3 billion years ago. Rock strata works best when it can be calibrated by radioactive dating, inclusion of fossils, and the strata represent rock that was laid down at known rates.

 

It takes ALL of these methods, comparing one against the other, to build a timeline that is reliable. Rock strata, used together with radio carbon, pollen fossils, and tree rings for calibration, can be incredibly accurate back to 100,000 years or more.

[Boerseun]

Scientific dating method?

 

Here's one - you start by buying her a nice graphing calculator. Then offer to re-attach her spectacles with a fresh band-aid. If you play your cards right, she might just let you handle her protractor. And who knows - with any luck (but not normally on first dates) she might just let you google her yahoo.

 

...but basically what Pyro said in the post upstairs.

[Moontanman]

You're a funny man Boerseun!

[Pyrotex]

You're a funny man Boerseun!

 

Hey! Looks aren't everything, you know!

[adamsmith709]

Hi,

The forum sounds so very interesting. Scientific Dating methods, I was wondering what such methods can be.It is something I have never heard of.So I would love to know about it in detail..So kindly reply back with your valuable suggestions people..

waiting for the replies..

:)

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