Potassium 40 dating

California and Washington states have been reassuring residents their monitoring has not detected any harmful radiation levels - and health officials do not expect to.‘Japan has an evacuation area of about 12 miles from the nuclear plants.Washington state is 5,000 to 6,000 miles away from Japan,’ a state health spokesman said.Worried Americans are panic-buying drugs to protect themselves against the nuclear fallout in Japan, as fears grow of harmful radiation blowing across to the West Coast. Ms Benjamin made the remarks to NBC Bay Area while touring a California hospital.Stocks of potassium iodide tablets, which aim to stop radiation poisoning the thyroid gland, are running low and customers missing out are said to be ‘crying’ or ‘terrified’. Anbex quickly sold out of a 10,000-strong supply of 14-tablet packages on Saturday.That is, a fresh mineral grain has its K-Ar "clock" set at zero.The method relies on satisfying some important assumptions: Given careful work in the field and in the lab, these assumptions can be met.Drug supplier sold 250,000 potassium iodide pills to pharmacies, labs, companies and hospitals last weekend, president Troy Jones told Fox News.It has back-ordered more than a million tablets and donated 50,000 to Japan.

Rock samples are recorded, marked, sealed and kept free of contamination and excessive heat on the way to the lab.Potassium occurs in two stable isotopes (Ar atoms trapped inside minerals.What simplifies things is that potassium is a reactive metal and argon is an inert gas: Potassium is always tightly locked up in minerals whereas argon is not part of any minerals. So assuming that no air gets into a mineral grain when it first forms, it has zero argon content.The rock sample to be dated must be chosen very carefully.

Any alteration or fracturing means that the potassium or the argon or both have been disturbed.

The site also must be geologically meaningful, clearly related to fossil-bearing rocks or other features that need a good date to join the big story.