Originally posted by Masherbrum
No, not at all, someone said he was a great speaker. I named two other's.
I am a Catholic. However, I have a piece of Banded Ironstone from the UP of Michigan. The rock is known dated as 3.6 billion years old. I showed it to a Baptist, he told me "the Earth was only 11,000 years old". C'est La Vie.
Hi Masherbrum,
Since you have a background in geology, I was wondering if you could decode the last paragraph below from a U Mich website about radiometric dating. I cannot get a clear understanding of what they are trying to say.
umich------------------
A useful analogy to illustrate the fundamentals of geochronology is an hourglass. If we start with one side of the hourglass full (containing the 'parent') and the other side empty (containing the 'daughter'), we only need to know the rate at which the sands moves from one chamber to the other (represented by the half-life) and the amount of sand in the daughter chamber or the amount of parent remaining to determine how much time has passed. However, in reality matters are more complex.
A complication occurs in natural samples because at the time the radiogenic clock starts ticking, the sample already contains some daughter material; in other words, some sand is already present in the daughter chamber even before we begin measuring time. This amount of daughter is referred to as the initial daughter. Therefore, when we measure the amount of daughter product in our specimen we are combining the amounts of daughter from decay of the parent and initial daughter. The amount of initial daughter, however, needs to be subtracted for age determination.
The solution to this problem lies in first determining the amount of initial daughter.
The actual method is a little tricky, but basically what we need is to find a part of the sample that contains no radiogenic 87Rb. The measured 87Sr in that part of the sample must therefore be initial daughter (i.e., non-radiogenic in origin). The tricky part comes from the fact that such a component cannot be found, but the same result may be obtained using components (minerals) of the sample that contain different amounts of 87Rb.
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Thanks
