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 42 375 LOWER PLIOCENE 137.5 138.0 NO AGE GIVEN NO AGE GIVEN 3.4 5 4.2 DSDP INITIAL REPORTS 42 375 UPPER MIOCENE 138.0 574.5 NO AGE GIVEN NO AGE GIVEN 5 10.5 7.75 DSDP INITIAL REPORTS 42 375 MIDDLE MIOCENE 622.0 679.0 NO AGE GIVEN NO AGE GIVEN 10.5 16 13.25 DSDP INITIAL REPORTS 42 375 LOWER MIOCENE 733.0 821.5 NO AGE GIVEN NO AGE GIVEN 16 22.5 19.25 DSDP INITIAL REPORTS