We’ve explored a fraction of the ocean, most of the Earth, and parts of our Solar System. But, do you ever wonder what everything around us is made up of? You might be surprised that the most abundant elements in the universe are limited on Earth.

What happens below the Earth’s crust is inaccessible to us, but not for our lack of trying. In 1970, we tried to dig a hole that would go below the crust. The hole was just 9 inches in diameter, and it’s considered to be the deepest hole in the world – in terms of true vertical depth.

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