In northern Chile the extremely dry Atacama desert along the coast leads up to the Altiplano. Scarce tropical summer rains from the Amazon basin only reach the Altiplano, but not the lower western side of Chile. At 3000 m, the desert passes into a semiarid alpine belt and different soils appear. Andosols are widespread due to modern volcanic activity. Beside them, the semi-arid Altiplano is characterized by salt lakes and hence, Solonchaks. Well developed Luvisols, which indicate wetter conditions than present, were formed during more humid periods of the Upper Pleistocene.