 Either during or before the last glacial maximum, Ampato erupted tephra during multiple explosive eruptions which today is preserved in two units, the Baylillas and the Corinta deposits.The first consists of lapilli, pumice and scoria and individual layers form thick sequences at large distances from the volcano, but are heavily eroded and thus difficult to measure in extent.Scoria flows identified on the southwestern-southern flanks of Ampato correspond to this unit.