The Atacama desert of Chile is a virtually rainless plateau made up of salt basins (salares), sand, and lava flows, extending from the Andes mountains to the Pacific Ocean.
The average width (east-and-west) is less than 160 kilometers but it extends from the Peruvian border 1000 kilometers south to the Bolivian Altiplano.
The Atacama Desert is the driest desert on Earth and is virtually sterile because it is blocked from moisture on both sides by the Andes mountains and by coastal mountains. The average rainfall is just 3mm per year, and there was a period of time where there was no rainfall for 40 years.