Last summer, I stood on a cliff 100 feet above the Madre De Dios River, in Southern Peru near the Bolivian border, to watch the rosy gift of an Amazon sunset. It was quiet, in a tropical rainforest way, with the light clamor of parrots, macaws, and cicadas. Then, a peke-peke motorized canoe broke through the soft din. It arrived from the east, carrying a new supply of diesel fuel for the gold miners who were prepping the generator that would operate a suction-pump and dredge for gold across the river and around the bend. Before nightfall, the fuel ignited the baritone of a diesel generator. It moaned all night and all day, barely stopping. In subsequent days, instead of a light clamor of birds and primates, the thrum of a gold mining operation seemed like all I could hear.