Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
smithsonianmag.com
Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
1–10 of 11 posts
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#2This appears to be how they computed the date: https://en.wikipedia.org/wiki/K%E2%80%93Ar_dating
With just 1 sample they can't conclude much, but if they find a bunch of others, they'll have an interesting set of datapoints from the composition of the tiny air pockets in the ice.
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#3Does this mean it should have 2.7 million ice core layers in the cross section?
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#4Does this mean it should have 2.7 million ice core layers in the cross section?
Apparently not. They say the ice "is not organized into neat layers", so they have approximated the age based on potassium and argon concentration.
Though it doesn't mention what potassium and argon have to do with age. Short explanation, anyone?
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#5Does this mean it should have 2.7 million ice core layers in the cross section?
Apparently not. They say the ice "is not organized into neat layers", so they have approximated the age based on potassium and argon concentration. Though it doesn't mention what potassium and argon have to do with age. Short explanation, anyone?
Isotopes of potassium decay to argon and the amount of accumulated argon - combined with knowledge of the decay rate - allows one to use the system as a clock:
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#6Earlier quoted context omitted.
Apparently not. They say the ice "is not organized into neat layers", so they have approximated the age based on potassium and argon concentration. Though it doesn't mention what potassium and argon have to do with age. Short explanation, anyone?
Isotopes of potassium decay to argon and the amount of accumulated argon - combined with knowledge of the decay rate - allows one to use the system as a clock: https://en.wikipedia.org/wiki/K%E2%80%93Ar_dating
that assumes you know how much it started with and what the environment was like then
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#7Does this mean it should have 2.7 million ice core layers in the cross section?
Apparently not. They say the ice "is not organized into neat layers", so they have approximated the age based on potassium and argon concentration. Though it doesn't mention what potassium and argon have to do with age. Short explanation, anyone?
But are there at least a million layers?
I mean, there have to be some amount of well preserved cycles from the compaction of snowfall right? It would be very strange if ALL the ice was not organized!
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#8Earlier quoted context omitted.
Isotopes of potassium decay to argon and the amount of accumulated argon - combined with knowledge of the decay rate - allows one to use the system as a clock: https://en.wikipedia.org/wiki/K%E2%80%93Ar_dating
that assumes you know how much it started with and what the environment was like then
It's safe to assume that these assumptions have been accounted for by the scientists developing and performing isotopic dating.
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#9Earlier quoted context omitted.
Isotopes of potassium decay to argon and the amount of accumulated argon - combined with knowledge of the decay rate - allows one to use the system as a clock: https://en.wikipedia.org/wiki/K%E2%80%93Ar_dating
that assumes you know how much it started with and what the environment was like then
The Wikipedia page covers these issues, albeit for crystalized rock instead of ice. The measurement is a ratio, so the key thing is establishing that Argon 40 is normally not present in rain or brand new ice.
Re: Scientists Find Record 2.7M-Year-Old Ice Core in Antarctica
#10Does this mean it should have 2.7 million ice core layers in the cross section?
No, the area where the ice was recovered is near the Allan Hills of the Transantarctic Mountains. This area isn't in the center of the ice sheet, where consistent accumulation patterns exist and drilling from the surface to the deepest ice would yield ~500k of these annual layers. The Allan Hills are on the fringe of the ice sheet, where the rock beneath the ice rises and due to some of the dynamic deformation mechanisms (and strong surface ablation) old ice is forced towards the surface. The researchers therefore aren't drilling from modern ice to this ancient ice, but are instead tapping directly into the old ice which is now exposed near the ice sheet surface.