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Assume there are several soil/rock (take it) samples as follows taken from different depth of the earth

sample from surface of the earth = Sample A
sample from 1km deep of the earth = Sample B
sample from 10km deep of the earth = Sample C
sample from 20km deep of the earth = Sample D
Cooled lava (in solid state) sample = Sample E (Assume lava was taken just after they cooled)

If these samples are tested using carbon 14 test what will be there ages according to test results?

NOTE: I'm not expecting any exact values.
Please order them in ascending order

As I think it should be in the order of A Because with the time new layer of soil/rock creates on top of the current existing layer and it's obvious(as I think) layer 1(first existed layer as the top layer) that first layer is older than new layer.
Above is my explanation.

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  • $\begingroup$ What have you tried? Why are you stuck? This is not a homework question, is it? $\endgroup$ – Jan Doggen Jun 13 '18 at 7:23
  • $\begingroup$ @JanDoggen, This is not a homework question. This is something came into my mind. That's all. I have my own explanation according to my knowledge. But I would like to find the real output if I do this $\endgroup$ – Joe Jun 13 '18 at 8:35
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    $\begingroup$ A "soil" sample 1 km deep, let alone 20 km is unrealistic. Rock samples at those depths would be more realistic. Soil generally extends to depths of tens of metres. Also such depths are arbitrary as they do not account for the geological history of the region being sampled. $\endgroup$ – Fred Jun 13 '18 at 8:39
  • $\begingroup$ Please add your own explanation according to my knowledge, so that we have something to address (I'm essentially repeating here What have you tried? Why are you stuck? - you have not answered those) $\endgroup$ – Jan Doggen Jun 13 '18 at 8:43
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Radiocarbon dating cannot be used to date rocks or lava, only organisms that absorbed carbon from the atmosphere in the last 50'000 years or so.

The older the samples, the more difficult it is to get an accurate age because the amount of 14C remaining becomes close to zero and thus the more likely it is that a few atoms of 14C from sample handling or atmospheric exposure may significantly change the number. That is why, for instance, coal contains trace amounts of 14C.

More generally, sample age does not always correlate with sample depth and it is strongly dependent on the geological setting. In a sedimentary basin, deeper rocks are older than shallower rocks but tectonic activity such as thrust faults and folds can upset this relationship.

In granitic and metamorphic terranes, there is no general correlation of age with depth, because granites intrude into older rocks

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  • $\begingroup$ That is a good explanation. I can agree with your answer. $\endgroup$ – Joe Jun 15 '18 at 4:24
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Geochron's answer is correct. For the sake of completeness I will add this:

sample from surface of the earth = Sample A

You will get some age, if the sample is young enough.

sample from 1km deep of the earth = Sample B

Low chance of getting any age.

sample from 10km deep of the earth = Sample C

Carbon-14 below detection limit.

sample from 20km deep of the earth = Sample D

Carbon-14 below detection limit.

Cooled lava (in solid state) sample = Sample E (Assume lava was taken just after they cooled)

Carbon-14 below detection limit.


I'll also add is that we are very limited in our capability to obtain samples from 10 or 20 kilometres deep.

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