Which stable element is used to determine the age of volcano rock
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One of the most common methods to date volcanic rocks uses potassium (radioactive parent) and argon (stable daughter). Potassium is an element found in many minerals and rocks, and it normally has an atomic mass of 39.

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey

If you remove all the lions from the savanna it will lead to a increase of gazelle and a increase of cheetahs becasue of no competition