AbstractOn the eastern side of the Atacama Desert an early Tertiary planation surface may be recognised across the major structures. Subsequent tectonic activity has taken place along particular lineaments and each episode has induced a period of dissection. The tectonic activity and associated dissection can be correlated with a period of ignimbrite deposition, and by inference with the period of Andean uplift. Isotopic ages on the ignimbrites can therefore be used to date Andean uplift. They suggest that uplift began in late Miocene times. Important later phases can be dated as mid‐Pliocene and Late Pliocene or Pleistocen