Answer:
potassium-argon dating
Explanation:
Potassium-argon (K-Ar) dating technique is the most appropriate dating method for establishing the age of a volcanic ash. It is most applicable for dating minerals and rocks more than 100,000 years old. It is based on measuring the product of the radioactive decay of an isotope of potassium (k) into argon (Ar). Since potassium is a common element found in many volcanic ash layer, the time since re-crystallization is calculated by measuring the ratio of the amount of argon 40 (Ar-40) accumulated to the amount of potassium 40 (K-40) remaining in these volcanic ashes.
The "policing of the Western Hemisphere" is a phrase that conveys Roosevelt's attitude when it came to international affairs. Roosevelt believed that the United States was justified in exercising this policing for several reasons. He argued that there had been chronic unrest or wrongdoing in the Western Hemisphere for a very long time, and someone had to put an end to it. Moreover, he stated that the United States would intervene in conflucts between European countries and Latin American countries if the European powers had a legitimate claim. He argued that this attitude would work because it came hand in hand with the Monroe Doctrine. While the Monroe Doctrine was meant to put an end to European intervention, the "corollary" (which stated the US intention to police the hemisphere) was used to justify American intervention.
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