The scale of an open-pit copper mine feels impossible; it is a Bible-grade phenomenon made by machines. Vehicles called bucket-wheel excavators, nearly five times the size of the largest dinosaurs, rip up the surface and gradually descend, piling 200,000 cubic meters or more of rock behind them every day. Once the copper is extracted, waste products and unrecoverable metals stream out as tailings, snaking tributaries that turn psychedelic-looking as they oxidize in open air for the first time in millions of years. Each excavator, meanwhile, turns the land it is standing on into a ledge and leaves a succession of these steps, or ‘‘benches,’’ behind it as it goes. The Chino Mine, for example, in Grant County, N.M., has been excavated persistently for more than a century and now stretches almost two miles across and 1,350 feet down. It’s a chasm, a void, a deep and disordered amphitheater built around an abyss. It gets four out of five stars on TripAdvisor.