Underneath the mountains and deserts of the U.S. West lie hundreds of thousands of abandoned mines, an underground world that can hold serious danger and unexpected wonder. Sometimes they'd come across an old mine shaft and toss a rock down, trying to imagine how far it fell. But the dangers of abandoned mines weigh on Utah officials' minds. Some abandoned mines become filled with tainted water, as in the toxic 2015 spill from Colorado's Gold King mine, but most in Utah are dry. The program has been around more than 30 years, and the division has already sealed some 6,000 abandoned mines.

Source: Fox News October 30, 2018 20:15 UTC