A just-unearthed cave formed more than 1 million years ago could yield new insight into the geological history of the American West, according to scientists, who called the discovery a major find. Four amateur cave explorers uncovered the vast caverns, stretching more than 1,000 feet into a remote mountainside, in August. Visitors to the cave, dubbed Ursa Minor, described seeing millions of crystals that shimmered like diamonds lodged in its walls. Translucent mineral curtains hung from the ceiling, and a lake possibly 20 feet deep filled one of the cave's five known rooms. Passages leading into darkness suggested there was...