On the banks of the Madre de Dios river, dredges work day and night in search of gold, part of a scourge of illegal mining that is slowly devouring the Peruvian Amazon. On the banks of the Madre de Dios river, dredges work day and night in search of gold, part of a scourge of illegal mining that is slowly devouring the Peruvian Amazon. Environment Phys.org – latest science and technology news stories