how are the ages of strata calculated?

Question

what methods are used in calculating how long a particular layer in the earth's crust has been there for?

Answer 1

We use radiometric dating techniques that use special, very long half-life isotopes (like, Rb-Sr, U-Pb, K-Ar, etc). These are grouped together and called: Geochronometer isotopes. When we derive an age this way in the lab, the result is called an absolute age (since it's looking at "absolute time"--which just means it's a number).



One can also use "relative time" techniques which are a little more vague. The rules here are called "Steno's Principles" and are in your textbook.



Also, as some above have mentioned, we also use fossils (well, index fossils) when they're present to estimate ages for some sediments.



This help??

Answer 2

The sequence of superposition of strata is the answer. In a normal sequence the oldest stratum is at the base and the youngest stratum is at the top. The individual stratum could be be millimeter thick to massive (>100-120cm) and would make no difference as far as superposition is concerned. If the sequence is fossiliferous (animal/plant) all through or even partly, fossils of the oldest life forms would occur in the lower stratum and the younger or evolving life forms would occur at the top. The age difference between the lower and upper stratum gives the age of the in between stratum or the age difference between the lowest and top most stratum gives the age of the whole sequence.

Now in case the sequence is unfossiliferous, then the age can be determined through radiometric dating.

In case of igneous rocks the age of the enveloping rocks and the mutual relations between rocks gives the older/younger relation ship and again radiometric dating can give the age.

In case of metamorphic rocks, the number of deformational imprints or metamorphic events and radiometric dating can gives the age.

thnks

Answer 3

a huge part is the fossils in them or in surrounding layers. If there is any organic matter possible C-14 dating, but thats very very unlikely because it only goes back 14 thousand years. Could also be dependent on what the other layers are around them. I.E.; If there is a layer between Jurassic and Tertiary its probably Cretaceous.

Answer 4

To be blunt, they do no longer. they have an theory that, if numerous minerals and factors have been accrued in a flood, they could separate into layers by way of a technique of differentiation, which may be layed down as a special, layered sediment. Kent Hovind even proposes an test that must be performed via each physique that ought to tutor this technique, which is composed of mixing a type of fabric in a field of water and seeing how they settle. needless to say, he never did his own test, yet potholer54debunks did it on Youtube. He observed Hovind's training completely to the letter and layered strata did no longer look; it replaced into purely a unmarried layer of airborne dirt and dust. He then repeated the test, purely he placed factors in a particular order, which he derived from how coastal sediment deposits are geared up up in accordance to geological examine. confident adequate, diverse, stratified layers have been obvious. The layers, in accordance to creationism, date back to the flood, which they sometimes have self assurance replaced into 4-6 thousand years in the past. The rocks themselves date to the creation, which they sometimes have self assurance replaced into 6-10 thousand years in the past. yet another argument i've got seen is that God chosen to create the rocks of the earth in layers. No reason or clarification is given; it truly is in simple terms that "God did it." on an identical time as this is consist with the existence of strata interior the 1st place (i ought to truly think of that a being effectual adequate to create the international ought to truly lay down sediments and rocks in layers), it truly is thoroughly unverifiable and it truly is a marginally ineffective assertion. it truly is not any longer a proof; it truly is in simple terms an assertion.

Answer 5

as a general rule, the deeper a stratum of rock the older it is.And sedimentary rocks are usually dated using fossils found inside the rocks

Answer 6

kalahari dude is right , its called the law of superposition. But this might not be as acurate and could be affected by things like faulting etc. I