A theory is a set of sentences which is closed to make logical implications.
I'm thinking it might be fossil evidence. Hope it helps!
Answer:
Argon
Explanation:
Argon is actually used to determine the age. It's called potassium-argon dating b/c when volcano erupts the rocks in it contain potassium. The potassium slowly decays and produces argon. Scientists measure how much argon is in a given volcanic rock and do math backwards to figure out how many potassium atoms were needed to produce the given amount of argon. We already know the rate at which potassium decays so then they put two and two together to find the age.
Here's a link with some cool info on it:
https://divediscover.whoi.edu/archives/hottopics/volcano.html
temperature regulation, heat absorption, and nutrition transportation
