The Tres Marias / Three Marys are among a number of surreal rock formations in the famous Valle de la Luna / Moon Valley near San Pedro de Atacama in northern Chile. The whitish deposits are salt; the area is part of the Cordillera de Sal range of hills and also the Los Flamencos National Park. Salt used to be mined in the region. The Atacama Desert stretches for over 1000km between the Pacific Ocean and the Andes and is the world's driest and probably oldest desert. In some areas rain has never been recorded, geological research suggests the region has been continuously arid for many millions of years.