An epoch of the early Tertiary period, spanning the time between 33.7 and 23.8 million years ago. It is named after the Greek words "oligos" (little, few) and "ceno" (new). The Superstition Mountains in Phoenix Arizona were completed during the Tertiary period. 

Weavers Needle - Peralta Canyon - Phoenix Arizona

Weavers Needle in Phoenix Arizona - created during the Oligocene epoch of the Tertiary period.