leg site hole age mnemonic auxiliary age mnemonic top of section depth(m) bottom of section depth(m) special condition age auxiliary age averaged age age top of section(million years) age bottom of section(million years) average age(million years)t data source 31 290 UPPER PLIOCENE 23.0 32.5 NO AGE GIVEN NO AGE GIVEN 1.8 3.4 2.6 DSDP INITIAL REPORTS 31 290 UPPER OLIGOCENE 99.0 165.5 NO AGE GIVEN NO AGE GIVEN 22.5 30 26.25 DSDP INITIAL REPORTS 31 290 LOWER OLIGOCENE 213.0 251.0 NO AGE GIVEN NO AGE GIVEN 30 37.5 33.75 DSDP INITIAL REPORTS 31 290 LOWER OLIGOCENE UPPER EOCENE 251.0 255.0 NO AGE GIVEN NO AGE GIVEN NO AGE GIVEN 30 43 36.5 DSDP INITIAL REPORTS