Mazama Ash overlying basalt, OregonApril 30, 2017/in /by Marli Miller volcanic, pyroclastic, tephra, airfall https://geologypics.com/wp-content/uploads/2017/04/geologic-time-pics-logo-300x115.png 0 0 Marli Miller https://geologypics.com/wp-content/uploads/2017/04/geologic-time-pics-logo-300x115.png Marli Miller2017-04-30 19:43:372017-09-06 21:28:32Mazama Ash overlying basalt, Oregon